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Evidence base medicine

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Tauseef Jawaid
Tauseef Jawaid

For the Students of Post graduate Courses in Public Health And Community Medicine

Salud y medicina
1 de 271
EVIDENCE BASED MEDICINEEVIDENCE BASED MEDICINE A new approach to clinical care and researchA new approach to clinical care and research
PROGRAM OUTLINE 1. Definition of EBM 2. Basic Steps 3. Trials, Studies and Reports 4. Pros, Cons and Limitations 5. EBM in Developing Countries 6. EBM Library 7. Advanced EBM
But first, a test…
A.A. Training, clinical experience and consultationTraining, clinical experience and consultation with other professionalswith other professionals B.B. Convincing evidence (non-experimental) fromConvincing evidence (non-experimental) from articles, case reports, product literature, etc.articles, case reports, product literature, etc. C.C. Preferences of the patientPreferences of the patient D.D. Active search of Randomized Controlled Trials,Active search of Randomized Controlled Trials, Systematic Reviews, Meta-Analysis ReportsSystematic Reviews, Meta-Analysis Reports WHAT IS THE BASIS OFWHAT IS THE BASIS OF YOURYOUR MEDICAL PRACTICE?MEDICAL PRACTICE? (Check all that apply)
A.A. Training, clinical experience and consultationTraining, clinical experience and consultation with other professionalswith other professionals B.B. Convincing evidence (non-experimental) fromConvincing evidence (non-experimental) from articles, case reports, product literature, etc.articles, case reports, product literature, etc. C.C. Preferences of the patientPreferences of the patient D.D. Active search of Randomized Controlled Trials,Active search of Randomized Controlled Trials, Systematic Reviews, Meta-Analysis ReportsSystematic Reviews, Meta-Analysis Reports WHAT IS THE BASIS OFWHAT IS THE BASIS OF YOURYOUR MEDICAL PRACTICE?MEDICAL PRACTICE? EXCELLLENT!EXCELLLENT!
BUT… Past knowledge and practice mightBUT… Past knowledge and practice might be outdated or inadequatebe outdated or inadequate
A.A. Training, clinical experience and consultation withTraining, clinical experience and consultation with other professionalsother professionals B.B. Convincing evidence (non-experimental) from articles,Convincing evidence (non-experimental) from articles, case reports, product literature, etc.case reports, product literature, etc. C.C. Preferences of the patientPreferences of the patient D.D. Active search of Randomized Controlled Trials,Active search of Randomized Controlled Trials, Systematic Reviews, Meta-Analysis reportsSystematic Reviews, Meta-Analysis reports WHAT IS THE BASIS OFWHAT IS THE BASIS OF YOURYOUR MEDICAL PRACTICE?MEDICAL PRACTICE? FANTASTIC!FANTASTIC!
BUT… This evidence may be biased, outdated,BUT… This evidence may be biased, outdated, incorrect, or not applicable to your patientincorrect, or not applicable to your patient ARTICLES ADVERTISEMENTS JOURNALS (1987 to present)
A.A. Training, clinical experience and consultation with otherTraining, clinical experience and consultation with other professionalsprofessionals B.B. Convincing evidence (non-experimental) from articles,Convincing evidence (non-experimental) from articles, case reports, product literature, etc.case reports, product literature, etc. C.C. Preferences of the patientPreferences of the patient D.D. Active search of Randomized Controlled Trials,Active search of Randomized Controlled Trials, Systematic Reviews, Meta-Analysis reportsSystematic Reviews, Meta-Analysis reports WHAT IS THE BASIS OFWHAT IS THE BASIS OF YOURYOUR MEDICAL PRACTICE?MEDICAL PRACTICE? WONDERFUL!WONDERFUL! Mutual Respect + Shared Goals = Better Cooperation and Compliance
The patient should be involved inThe patient should be involved in all important decisionsall important decisions But this isBut this is NOTNOT always an easy task!always an easy task! And conflictsAnd conflicts WILLWILL occur!occur!
But doctor, I DO want to have children! No salt? Lose weight? Forget it! Just give me a pill! I WON’T take that medicine… The side effects are INTOLERABLE! And conflictsAnd conflicts WILLWILL occur!occur!
Education about current alternatives and risks is oftenEducation about current alternatives and risks is often needed…needed… for both the Patientfor both the Patient andand the Doctor!the Doctor! But doctor, I DO want to have children! No salt? Lose weight? Forget it! Just give me a pill! I WON’T take that medicine… The side effects are INTOLERABLE!
I’ll discuss those risks with my husband. Yes, I’d like to try that new medication! Wow… I never knew that high blood pressure could be so dangerous at my age! Education about current alternatives and risks is oftenEducation about current alternatives and risks is often needed…needed… for both the Patientfor both the Patient andand the Doctor!the Doctor!
The patient’s preferences MUST be considered!The patient’s preferences MUST be considered! An important rule in Evidence Based Medicine…An important rule in Evidence Based Medicine… ItIt STARTSSTARTS with the patient andwith the patient and ENDSENDS with the patient.with the patient.
A. Training, clinical experience and consultation with other professionals B. Convincing evidence (non-experimental) from articles, case reports, product literature, etc. C. Preferences of the patient D. Active search of Randomized Controlled Trials, Systematic Reviews, Meta-Analysis reports WHAT IS THE BASIS OFWHAT IS THE BASIS OF YOURYOUR MEDICAL PRACTICE?MEDICAL PRACTICE? WOW!!! SUPERB!!!
In the practice of Evidence Based Medicine, it isIn the practice of Evidence Based Medicine, it is the physician’sthe physician’s dutyduty to find the best and mostto find the best and most current information and apply it judiciously for thecurrent information and apply it judiciously for the benefit of the patient.benefit of the patient.
But… A practice based exclusively on science and math is effective only if your patients are robots or clones! Don’t forget to allow for individual human differences and personal preferences!
A. Training, clinical experience and consultation with other professionals B. Convincing evidence (non-experimental) from articles, case reports, product literature, etc. C. Preferences of the patient D. Active search of Randomized Controlled Trials, Systematic Reviews, Meta-Analysis reports WHAT IS THE BASIS OFWHAT IS THE BASIS OF YOURYOUR MEDICAL PRACTICE?MEDICAL PRACTICE? If you checked all 4 items…If you checked all 4 items…
A. Training, clinical experience and consultation with other professionals B. Convincing evidence (non-experimental) from articles, case reports, product literature, etc. C. Preferences of the patient D. Active search of Randomized Controlled Trials, Systematic Reviews, Meta-Analysis reports YouYou areare practicingpracticing EVIDENCE BASEDEVIDENCE BASED MEDICINE!MEDICINE! CONGRATULATIONS!
EVIDENCE BASED MEDICINEEVIDENCE BASED MEDICINE A new approach to clinical care and researchA new approach to clinical care and research 1. Definition of EBM 2. Basic Steps 3. Trials, Studies and Reports 4. Pros, Cons and Limitations 5. EBM in Developing Countries 6. EBM Library 7. Advanced EBM
““WhatWhat isis Evidence Based Medicine?”Evidence Based Medicine?” ““And where did it come from?”And where did it come from?”
A BRIEF HISTORYA BRIEF HISTORY 1980’s: McMasters University in Ontario, Canada1980’s: McMasters University in Ontario, Canada Dr. David Sackett and colleagues proposed EvidenceDr. David Sackett and colleagues proposed Evidence Based Medicine (EBM) as a new way of teaching, learningBased Medicine (EBM) as a new way of teaching, learning and practicing medicine.and practicing medicine. Dr. Sackett defines EBM as:Dr. Sackett defines EBM as: “…“…The conscientious, explicit, and judicious useThe conscientious, explicit, and judicious use of current best evidence in making decisionsof current best evidence in making decisions about the care of individual patients.”about the care of individual patients.”
Evidence Based Medicine It is a change in the way physicians practice medicine, teach and learn, and handle research. Clinical practice: Based on the best current evidence (not necessarily on how it’s always been done) Patient Care: Compassionate, patient-oriented (less authoritarian) Learning & Teaching: Problem-based, problem-solving more investigative, less know-it-all-by-yesterday Research: More stringent approach, better proof criteria (more demanding of proof, less room for error)
PATIENT PHYSICIAN INFORMATION THREE MAJOR COMPONENTS of EBM
PATIENT Values, Concerns Preferences, Expectations Life predicament PHYSICIAN Training & Experience Current Expertise Continued learning Demand for proof INFORMATION Clinically relevant Proven by research Best up-to-date evidence EBM THE ADDED DETAILS
PATIENT Values, Preferences Concerns, Expectations Life predicament PHYSICIAN Training Expertise Continued Learning Demand for proof EBM CHARITY EBM is not a required practice (yet) ENTHUSIASM Challenge, Variety, Change HUMILITY Non-authoritarian practice OPTIONAL COMPONENTS TO BE ADDED BY THE PHYSICIAN INFORMATION Clinically relevant Proven by research Current, up to date
“Isn’t this the way we have always practiced medicine?” “Aren’t these just the same old ingredients tossed into a new recipe?” When am I supposed to find the time to do that?
The basic steps of EBM
THE FIVE BASIC STEPS OF EBM 1. Clinical Question Patient-focused, problem-oriented 2. Find Best Evidence Literary Search 3. Critical Appraisal Evaluate evidence for quality and usefulness 4. Apply the Evidence Implement useful findings in clinical practice 5. Evaluate The information, intervention, and EBM process
THE FIVE BASIC STEPS OF EBM 1. Clinical Question Patient-focused, problem-oriented 2. Find Best Evidence Literary Search 3. Critical Appraisal Evaluate evidence for quality and usefulness 4. Apply the Evidence Implement useful findings in clinical practice 5. Evaluate The information, intervention, and EBM process
THE FIVE BASIC STEPS OF EBM 1. Clinical Question Patient-focused, problem-oriented 2. Find Best Evidence Literary Search 3. Critical Appraisal Evaluate evidence for quality and usefulness 4. Apply the Evidence Implement useful findings in clinical practice 5. Evaluate The information, intervention, and EBM process
THE FIVE BASIC STEPS OF EBM 1. Clinical Question Patient-focused, problem-oriented 2. Find Best Evidence Literary Search 3. Critical Appraisal Evaluate evidence for quality and usefulness 4. Apply the Evidence Implement useful findings in clinical practice 5. Evaluate The information, intervention, and EBM process
THE FIVE BASIC STEPS OF EBM 1. Clinical Question Patient-focused, problem-oriented 2. Find Best Evidence Literary Search 3. Critical Appraisal Evaluate evidence for quality and usefulness 4. Apply the Evidence Implement useful findings in clinical practice 5. Evaluate The information, intervention, and EBM process
THE FIVE BASIC STEPS OF EBM 1. Clinical Question Patient-focused, problem-oriented 2. Find Best Evidence Literary Search 3. Critical Appraisal Evaluate evidence for quality and usefulness 4. Apply the Evidence Implement useful findings in clinical practice 5. Evaluate The information, intervention, and EBM process
The Clinical QuestionThe Clinical Question The FIRST stepThe FIRST step The HARDEST stepThe HARDEST step TheThe MOST IMPORTANTMOST IMPORTANT step!step!
FACT: We all have informational needs! That is not a problem!
Problems ariseProblems arise • if we fail to recognize those needsif we fail to recognize those needs • if we fail to bridge the information gapif we fail to bridge the information gap • if we fail to ask the right questionsif we fail to ask the right questions
And also for othersAnd also for others aroundaround you!you! Lee, exactly how much time did you spend on that big project? Hmmm… Is he about to give me a BONUS? Or is he about to FIRE me? It will make lifeIt will make life easier for you...easier for you... Asking good questionsAsking good questions is ais a skillskill tto be learned.
A GOOD QUESTION…A GOOD QUESTION… • Is focused and relevantIs focused and relevant • Provides clearProvides clear communicationcommunication • Clarifies your goal or needClarifies your goal or need • Will reduce the amount ofWill reduce the amount of time needed to obtain thetime needed to obtain the answeranswer Lee, can you give me an accounting of the extra time you spent on that project so that I can charge it back to the client? Oh sure! I’ll have it on your desk by tomorrow!
• Be specificBe specific Identify the problem, clarifiy the clinical issue • Be answerableBe answerable through the literature • Contain multiple aspectsContain multiple aspects (patient, options, comparisons, etc) WHEN PRACTICING EBM,WHEN PRACTICING EBM, a good question must also:a good question must also: ACTUAL CASE SCENARIOACTUAL CASE SCENARIO Large cauc male, age 40 2mo ago: Presented with classic nephrotic syndrome, significant symptoms. Bx showed IgAN. Cr 1.4, incr to 2 range, now 1.6 Tried prednisone 60mg qd - tolerated poorly w/tremors and depression. Needs new regimen, but others are aimed more at nephritic IgA rather than nephrotic syndrome. Suggestions? It shouldIt should NOTNOT involve ainvolve a question of Personal Preferencequestion of Personal Preference or Local Concern.or Local Concern.
THE EVIDENCE BASED RESPONSETHE EVIDENCE BASED RESPONSE Posted on Nephrol 4/13/03 “In the study below, proteinuria and renal function improved on this combination: Ballardie FW, Roberts IS. Controlled prospective trial of prednisolone and cytotoxics in progressive IgAN. J Am Soc Nephrol 2002 Jan….” “I have patients on this regime who have benefitted.” Regards, Dr. Paulose P. Thomas Nephrologist - Belhoul Apollo Hospital, Dubai, UAE Respondant recommends cyclophosphamide and prednisolone (assuming secondary causes excluded) - a combination that allows for lower dose prednisolone…
BACKGROUND and FOREGROUND QUESTIONSBACKGROUND and FOREGROUND QUESTIONS (all part of EBM)(all part of EBM) FOREGROUNDFOREGROUND QUESTIONSQUESTIONS BACKGROUND QUESTIONSBACKGROUND QUESTIONS NEW POSSIBILITIESNEW POSSIBILITIES INDEFINITE ANSWERSINDEFINITE ANSWERS “Where do we want to go, and how else might we get there?” EXPERTGRADSTUDENT “Where are we now? And which way are we headed?” BASIC & CONCRETEBASIC & CONCRETE
BACKGROUND QUESTIONSBACKGROUND QUESTIONS BASIC & CONCRETEBASIC & CONCRETE 1. QUESTION • Who, What, Where, When, Why, How 2. VERB • is, causes, does, treats, reduces, cures, prevents, affects 3. GENERAL KNOWLEDGE ABOUT DISORDER clinical manifestations of disease, patient findings, differential diagnosis, etiology, patient experience, comorbid condition, screening and diagnostic tests, prognosis, therapy, risk factors, etc. EXPERTGRADSTUDENT
FOREGROUND QUESTIONSFOREGROUND QUESTIONS NEW POSSIBILITIESNEW POSSIBILITIES INDEFINITE ANSWERSINDEFINITE ANSWERS PT AND/OR PROBLEM Differential dx, Unusual presentation, uncertain etiology, pt’s prior experience, comorbid conditions INTERVENTION Exposure, test. Prognostic factor, treatment, pt perception, etc. COMPARISON INTERVENTION OUTCOMES EXPERTGRADSTUDENT
EBM QUESTIONEBM QUESTION:: Should include multiple factorsShould include multiple factors (Examples)(Examples) PP PATIENTPATIENT type of patient or population Ex: 47 yr male w/DM2 and cellulitis toe, 25 yr female w/DVT and chest pain EE EXPOSUREEXPOSURE environmental, personal, biological Ex: TB, tobacco, drug, diet, pregnancy or menopause, MRSA, allergy II INTERVENTIONINTERVENTION clinical intervention Ex: medication, procedure, test, surgery, radiation, drug, vaccine CC COMPARISONCOMPARISON compare alternative treatment Ex: other prior, new or existing therapy OO OUTCOMEOUTCOME clinical outcome of interest Ex: Reduced death rate in 5 yrs, decreased infections, fewer hospitalizations
FRAMING THE QUESTION (Example: PICO)FRAMING THE QUESTION (Example: PICO) ELEMENTELEMENT PROMPTS THE QUESTIONPROMPTS THE QUESTION:: PatientPatient How would I describe a group of patients similar to mine?How would I describe a group of patients similar to mine? InterventionIntervention What main action am I considering?What main action am I considering? ComparisonComparison What is/are the other options?What is/are the other options? OutcomeOutcome What do I (or the patient) want to happen (or not happen)?What do I (or the patient) want to happen (or not happen)? Example:Example: P:P: In kids under age 12 with poorly controlled asthma on meteredIn kids under age 12 with poorly controlled asthma on metered dose inhaled steroids…dose inhaled steroids… I:I: would the addition of salmetrol to the current therapywould the addition of salmetrol to the current therapy C:C: compared to increasing the dose of current steroidcompared to increasing the dose of current steroid O:O: lead to better control of symptoms without increasing side effects?lead to better control of symptoms without increasing side effects?
CATEGORY OF QUESTIONCATEGORY OF QUESTION MAJOR CATEGORIESMAJOR CATEGORIES 1.1. DiagnosisDiagnosis 2.2. PrognosisPrognosis 3.3. Therapy/ TreatmentTherapy/ Treatment PICO 4.4. Harm (iatrogenic, other)Harm (iatrogenic, other) PEO MISCELLANEOUS • Quality of care • Health economics • Office Management • Etc.
THE PATIENT’S QUESTIONSTHE PATIENT’S QUESTIONS MustMust be considered!be considered! Often QUALITATIVEOften QUALITATIVE (not based on measureable outcomes) Feelings, ideas, experiences, preferences, concerns, fears, beliefs, ethnicity Usually based on LIMITED BACKGROUNDUsually based on LIMITED BACKGROUND Perception of problem Self-diagnosis Treatment wanted or needed Alternatives (read, heard, considered, tried) What is the patient hoping to avoid? What benefits does the patient want or need most? Etc.
QUANTITATIVEQUANTITATIVE: “: “Solid EvidenceSolid Evidence”” • Measurable answer or responseMeasurable answer or response • Necessary for scientific studyNecessary for scientific study • Necessary for the practice of EBMNecessary for the practice of EBM QUALITATIVEQUALITATIVE: “: “Quality of LifeQuality of Life”” • ““Fuzzy” data - Impact on daily life, work, family, etc.Fuzzy” data - Impact on daily life, work, family, etc. • May be very important and influential to decisions –May be very important and influential to decisions – especially for the patientespecially for the patient • Creates added challenge or twist to practice of EBMCreates added challenge or twist to practice of EBM QUANTITATIVE vs QUALITATIVE QUESTIONSQUANTITATIVE vs QUALITATIVE QUESTIONS
QUALY: QUALITY ADJUSTED LIFE YEAR 0 2 4 6 8 10 1 2 3 4 5 5-yrTREATMENT COMPARISON Chemo&Rad Radiation only Chemo only 1 2 3 4 5 6 7 8 9 10 2 3 4 5 6 7 8 9 10 PERFECT HEALTH 1 2 3 4 5 6 7 8 9 10 2 3 4 5 6 7 8 9 10 CHRONIC MEDIOCRITY 0 1 2 3 4 5 6 7 8 9 2 3 4 5 6 7 8 9 10 DETERIORATING HEALTH
THE FIVE BASIC STEPS OF EBM 1. Clinical Question Patient-focused, problem-oriented 2. Find Best Evidence Literary Search 3. Critical Appraisal Evaluate evidence for quality and usefulness 4. Apply the Evidence Implement useful findings in clinical practice 5. Evaluate The information, intervention, and EBM process
Find the Best EvidenceFind the Best Evidence “The Literary Search”“The Literary Search” HINT: If your desk looks like this, it’s probably the LAST place you should start looking!
Find the Best EvidenceFind the Best Evidence “The Literary Search”“The Literary Search” The BEST EVIDENCE isThe BEST EVIDENCE is:: ExternalExternal - from outside resources (researchers, experts) CurrentCurrent – not out of date, most recent High QualityHigh Quality - accurate, precise, effective, safe Patient focusedPatient focused - applicable and appropriate for your individual patient
FIVE STEPS TO FINDING THE BEST EVIDENCE 1. IDENTIFY NEEDS: What type of information is needed? 2. IDENTIFY RESOURCES: Types, Availability, Timeliness,Costs? 3. SEARCH & RETRIEVE: Use efficient strategies 4. REVIEW : Check quality and usefulness of info 5. INTERPRET: Help patient understand info, application
WHAT TYPE OF INFORMATION IS NEEDED?WHAT TYPE OF INFORMATION IS NEEDED? WHAT CATEGORY IS THEWHAT CATEGORY IS THE QUESTION?QUESTION? • DiagnosisDiagnosis • PrognosisPrognosis • TherapyTherapy • HarmHarm
WHAT STUDY DESIGN FITS IT BEST?WHAT STUDY DESIGN FITS IT BEST? There are MANY study designs!There are MANY study designs! EXPERIMENTAL TRIALSEXPERIMENTAL TRIALS (Answers questions of diagnosis or treatment) Randomized Controlled Trials (RCTs) Controlled studies Blinded vs Open ETC. OBSERVATIONAL STUDIESOBSERVATIONAL STUDIES Descriptive reports Retrospective studies Cohort studies Case Control ETC.
EXAMPLE Randomized Controlled Trials (RCT) “Gold Standard” of research Ideal experimental design - Best design for TREATMENT questions Must identify objective of treatment (Ex: cure, prevent complication, palliation, reassurance) Still not always the right intervention for individual patient at that particular time and place
What type of evidence best addresses the question, problem or issue? CLINICAL PRACTICECLINICAL PRACTICE APPROPRIATE DESIGN FOR CLINICAL RESEARCHAPPROPRIATE DESIGN FOR CLINICAL RESEARCH Diagnosis, Dx testing Cross-sectional study – not randomized trial Prognosis Follow-up studies of patients evaluated at same early point of illness Therapy, treatment RCT or Systematic review of multiple RCTs must be used Avoid non-experimental approaches to avoid false conclusions about efficacy Exceptions: When treatment may be successful in an otherwise fatal condition When no studies are available (rare conditions, new treatments, etc.) Harm RCT, Cohort, Case-control OTHER INFORMATIONALOTHER INFORMATIONAL Explore hypothesis Qualitative research History-taking Case control study Individual trial & error n of 1 trial Following clinical course Cohort study Recordkeeping Systematic registry-based (computer supported) research Quality of Care research Individual peer review, Process Evaluation MISCELLANEOUSMISCELLANEOUS Basic Science, Genetics, Immunology, etc.
WHAT FORM OF INFORMATION?WHAT FORM OF INFORMATION? Case report Controlled Trial Systematic review Meta-analysis Clinical guidelines etc.
LITERARY SEARCH: NEXT STEPLITERARY SEARCH: NEXT STEP IDENTIFY YOUR RESOURCESIDENTIFY YOUR RESOURCES ColleaguesColleagues Consultation, DiscussionConsultation, Discussion (Caution: Response may be an outdated “This is what we(Caution: Response may be an outdated “This is what we do”)do”) Paper resourcesPaper resources books, reports, journalsbooks, reports, journals Electronic databasesElectronic databases Health Literature ServicesHealth Literature Services specialized librarians, staffspecialized librarians, staff Review services, Abstract Services, etc.Review services, Abstract Services, etc.
SEARCH AND RETREIVE THE BEST EVIDENCESEARCH AND RETREIVE THE BEST EVIDENCE Learn and Practice various SEARCH STRATEGIESLearn and Practice various SEARCH STRATEGIES:: • To find useful information quicklyTo find useful information quickly • To eliminate irrelevant, inappropriate or weak informationTo eliminate irrelevant, inappropriate or weak information Try to develop the habit of learning as you go;Try to develop the habit of learning as you go; Not just in lengthy formal sessions!Not just in lengthy formal sessions!
LITERARY SEARCH STRATEGYLITERARY SEARCH STRATEGY ASK FOR HELP!ASK FOR HELP! SPECIALIZED PERSONNELSPECIALIZED PERSONNEL • track down information, textbooks, articles,track down information, textbooks, articles, guidelinesguidelines • may provide electronic search support or trainingmay provide electronic search support or training EXAMPLESEXAMPLES • Medical Librarians • Medical Informatics Specialists • Specially trained staff member
LITERARY RESOURCESLITERARY RESOURCES • TEXTBOOKS (caution – most obsolete!)TEXTBOOKS (caution – most obsolete!) • TraditionalTraditional • Evidence BasedEvidence Based • JOURNALS (may be outdated)JOURNALS (may be outdated) • REVIEW ARTICLES (summaries, abstracts)REVIEW ARTICLES (summaries, abstracts) • SYSTEMATIC REVIEWS (prepared in systematic, rigorousSYSTEMATIC REVIEWS (prepared in systematic, rigorous manner)manner) Ex: Cochrane CollectionEx: Cochrane Collection • META-ANALYSISMETA-ANALYSIS • CLINICAL PRACTICE GUIDELINESCLINICAL PRACTICE GUIDELINES Summarized and easily digestible informationSummarized and easily digestible information
ELECTRONIC RESOURCES, DATABASES, INTERNETELECTRONIC RESOURCES, DATABASES, INTERNET Bibliographic DatabaseBibliographic Database Example: Medline, PubMedExample: Medline, PubMed Medical Information Services: Medscape, HDCNMedical Information Services: Medscape, HDCN Review ServicesReview Services SubjectiveSubjective Systematic ReviewsSystematic Reviews Meta-analysisMeta-analysis Examples:Examples: • Cochrane,Cochrane, • Best Evidence,Best Evidence, • Up to DateUp to Date
MORE GREAT INTERNET RESOURCESMORE GREAT INTERNET RESOURCES WebsitesWebsites cyberNephrology, National Kidney Foundation. NIDDK,cyberNephrology, National Kidney Foundation. NIDDK, American Heart Association, American Cancer Society.American Heart Association, American Cancer Society. National Institutes of Health, etcNational Institutes of Health, etc Listserve Discussion GroupsListserve Discussion Groups CyberNephrology, C-span, etc.CyberNephrology, C-span, etc. Specialty Electronic DatabasesSpecialty Electronic Databases PsyclitPsyclit CancerLitCancerLit CINAHLCINAHL (allied health and nursing journals)(allied health and nursing journals) EtcEtc
OTHER RESOURCESOTHER RESOURCES TapesTapes VideosVideos CD-ROMsCD-ROMs Specialty seminarsSpecialty seminars Product information and comparisonsProduct information and comparisons
A closer look at some Internet Resources…
MEDLINEMEDLINE WHAT IS IT?WHAT IS IT? Searchable database of medical information compiled by National Library ofSearchable database of medical information compiled by National Library of Medicine in US 1966-presentMedicine in US 1966-present Catalogs articles from approx 4000 world journals (of estimated 12-15k total)Catalogs articles from approx 4000 world journals (of estimated 12-15k total) SEARCH METHODSSEARCH METHODS Any word or words (title, abstract, content, author name, institution, etc.)Any word or words (title, abstract, content, author name, institution, etc.) Medical Subject Heading (MeSH) termsMedical Subject Heading (MeSH) terms A restricted thesaurus of medical titlesA restricted thesaurus of medical titles Articles categorized by most specific possible MeSH headingArticles categorized by most specific possible MeSH heading
COST: FREE!COST: FREE! Or may subscribe to companies with specialized search strategies: • Ovid Technologies (ovid) • Silver Platter Information (WinSPIRS) BENEFITSBENEFITS Free Vast database LIMITATIONSLIMITATIONS Not all articles are indexed on Medline (only 1/3 of approx 10 million!) Much material listed and described on Medline can only be accessed through journal article
MEDLINE: ELECTRONIC SEARCH STRATEGIES Search through “Clinical Queries” service of PubMed http://www.ncbi.nlm.nih.gov/clinical.html Medical Subject Headings (MeSH) Search filters Search by a text word can supplement a MeSH search Boolean search: “and”, “not”, etc. To increase sensitivity • use “explode” command • avoid using subheadings Online Tutorial is available!Online Tutorial is available!
COCHRANE LIBRARY Cochrane Database of Systematic Reviews -systematically compiled reviews of intervention Cochrane Controlled Trials Register -citations of controlled trials identified anywhere in the world Cochrane Review Methodology Database -methodological papers relating to systematic reviews Etc.
BEST EVIDENCE Electronic version of two publications: • Evidence Based Medicine • American College of Physicians Journal Club Covers broad topics of information
THE FIVE BASIC STEPS OF EBM 1. Clinical Question Patient-focused, problem-oriented 2. Find Best Evidence Literary Search 3. Critical Appraisal Evaluate evidence for quality and usefulness 4. Apply the Evidence Implement useful findings in clinical practice 5. Evaluate The information, intervention, and EBM process
CRITICAL APPRAISALCRITICAL APPRAISAL Interpreting the evidenceInterpreting the evidence • How to read a paperHow to read a paper • How to do the mathHow to do the math
CRITICAL APPRAISALCRITICAL APPRAISAL IMPORTANT!IMPORTANT! You doYou do NOTNOT have to become a researcher,have to become a researcher, epidemiologist, or statistician to practice EBM.epidemiologist, or statistician to practice EBM. Focus on how toFocus on how to USEUSE research reports –research reports – not on how to generate them!not on how to generate them!
HOWEVER…HOWEVER… You must have a solid understanding ofYou must have a solid understanding of basic research principlesbasic research principles andand study designsstudy designs in order to understandin order to understand and interpret the evidence!and interpret the evidence! CRITICAL APPRAISALCRITICAL APPRAISAL
TYPES OF STUDIES AND REPORTS Randomized Controlled Trial - “The Gold Standard” Systematic review Meta-analysis Retroactive vs Prospective Incidence Prevalence Case Control Cohort (Follow-up) Cross-sectional Ecologic Longitudinal Experimental Blinded vs Open Qualitative Screening
DETOUR
BASIC RESEARCH PRINCIPLES STUDY DESIGNS
THETHE TIMETIME FACTORFACTOR When was the study done?When was the study done? In what time direction is it headed?In what time direction is it headed? What was its duration?What was its duration? RETROSPECTIVE PROSPECTIVEPROSPECTIVE
THETHE TIMETIME FACTORFACTOR When was the study done?When was the study done? What year?What year? What technology? (ie: test, drug, equipment, procedure)What technology? (ie: test, drug, equipment, procedure) Any associated social factor or historical event?Any associated social factor or historical event?
THETHE TIMETIME FACTORFACTOR What was the Study Duration?What was the Study Duration? Was it an appropriate length of time for the intended goal? Limited time study or ongoing? Was study completed? Stopped early?
““LOOKING BACKLOOKING BACK”” Historical Review orHistorical Review or InvestigationInvestigation ““LOOKING FORWARDLOOKING FORWARD”” Future ResultsFuture Results The Great UnknownThe Great Unknown PRESENTPAST FUTURE In what direction is it headed?In what direction is it headed? RETROSPECTIVE PROSPECTIVEPROSPECTIVE
PROPRO •May provide goodMay provide good direction for future studydirection for future study ““Hind Sight is 20/20”Hind Sight is 20/20” CON:CON: •Prone to BiasProne to Bias •A“Fishing Expedition” forA“Fishing Expedition” for positive resultspositive results PROPRO •Lower risk of biasLower risk of bias CON:CON: May get faulty results basedMay get faulty results based on incomplete data oron incomplete data or insignificant subgroupsinsignificant subgroups (Example of Error: Untreated(Example of Error: Untreated hypertension unlikely to causehypertension unlikely to cause cardiac event in child, so treatmentcardiac event in child, so treatment is unnecessary below age 18yrs)is unnecessary below age 18yrs)PRESENT In what direction is it headed?In what direction is it headed? RETROSPECTIVE PROSPECTIVEPROSPECTIVE
“Was there a similar comparison group?”
Experimental Intervention No comparison group All subjects receive Experimental Intervention
Experimental Intervention NO EVENT OUTCOME EVENT ““Trial and Error?Trial and Error?”” or ““Before & After?Before & After?”” UNCONTROLLED STUDIES
PROBLEMS POSITIVE OUTCOME MAY BE DUE TO: •Other factors •Natural course of disease (some get better, some don’t!) •Spontaneous change of health •Placebo Effect •Hawthorne Effect NEGATIVE OUTCOME May be due to study treatment. Could be disastrous! BENEFITS Can answer some questions about: •likelihood of response •adverse effect, etc. VERY PATIENT-SPECIFIC! MAY BE ONLY OPTION Rare conditions Previously unknown conditions ““Trial and ErrorTrial and Error”” ““Before & AfterBefore & After”” UNCONTROLLED STUDIES Generally NOT accepted: Potentially Dangerous and Flawed Prone to BIAS! “Traditional Study Method” May produce strong results
SMALLPOX VACCINATION SMALLPOX VACCINE 1. 1796: Edward Jenner inoculates 8yr-old James Phipps with cowpox virus from a milkmaid’s hands. Child develops illness, recovers. 2. Two weeks later, inoculates same child with smallpox virus. Child survives, no illness. (Centuries later, smallpox eradicated!) n=1 GOOD! Resistant to Cowpox and Smallpox (NO DISEASE OUTCOME) James Phipps, age 8 years Example#1Example#1 UNCONTROLLED TRIALS: “TRIAL AND ERROR”
Drinks culture of H.pylori HELICOBACTER PYLORI - GASTRIC ULCERS 1982: Australian microbiologist Barry J. Marshall presents evidence showing a possible infectious cause for gastric ulcers. Suggests they may be treatable with antibiotics. Findings are met with disinterest and disbelief by medical community. Lacks support for further study. 5 years later: Prepares a broth of live organisms isolated from a gastric ulcer patient and drinks it. Becomes violently ill, develops severe acute gastritis. 1990’s Antibiotics are used routinely to cure some gastric ulcers! Example #2Example #2 NO OUTCOME SEVERE GASTRITIS n=1UNCONTROLLED TRIALS: “TRIAL AND ERROR” Dr. Marshall Microbiologist
UNCONTROLLED TRIAL Experimental Intervention Present FUTURE May represent the ONLY treatment option for a new or rare disease DIED RECOVERED
Experimental Intervention Control Group STRONGLY PREFERRED! Reduces BIAS. Provides stronger results.
Nothing Placebo Observation only ExperimentalI ntervention Control group may receive… Only the TEST group receives the Experimental Intervention CONTROLLED STUDY Other IMPORTANT All other differences should be minimized or eliminated to reduce potential BIAS Gold Standard Treatment
Experimental Intervention Control Group RANDOMIZEDRANDOMIZED CONTROLLEDCONTROLLED TRIAL (RCT)TRIAL (RCT) ““The GoldThe Gold Standard”Standard”
1944 TUBERCULOSIS TREATMENT: Streptomycin vs Bedrest1944 TUBERCULOSIS TREATMENT: Streptomycin vs Bedrest Streptomycin (n=50) Bedrest (n=50) THE FIRST RANDOMIZED CONTROLLED TRIAL By Sir Austin Bradford Hill (BLINDED)
Experimental Intervention Control Group OPEN vs BLINDED STUDIESOPEN vs BLINDED STUDIES OPENOPEN
BLINDED TRIAL BLINDED TRIAL BLINDEDBLINDED OPEN vs BLINDED STUDIESOPEN vs BLINDED STUDIES
BLINDING SINGLE BLINDED: Pt unaware of what group s/he is in DOUBLE BLINDED: Pt and MD unaware OPEN LABEL: Everyone is aware
RANDOMIZED vs NON-RANDOMIZED TRIALSRANDOMIZED vs NON-RANDOMIZED TRIALS Experimental Intervention Control Group How is this group divided?
NON-RANDOMIZEDNON-RANDOMIZED Experimental Intervention Control Group Assigned toAssigned to groups, usuallygroups, usually by theby the researcherresearcher Potential for RESEARCHER BIAS!Potential for RESEARCHER BIAS!
RANDOMIZEDRANDOMIZED Experimental Intervention Control Group Random method ofRandom method of assignment usedassignment used Maximizes “sameness,” Eliminates BIAS!Maximizes “sameness,” Eliminates BIAS!
RANDOMIZEDRANDOMIZED CONTROLLED TRIAL (RCT)CONTROLLED TRIAL (RCT) (EXPERIMENTAL TRIAL)(EXPERIMENTAL TRIAL) Experimental Intervention Control Group Present FUTURE ““The Gold Standard”The Gold Standard”
Experimental Intervention Trial of Medicine 1 Or placebo TRIAL SERIES FOR INDIVIDUAL PATIENT n=1One patient, series of tests Experimental Intervention Trial of Medicine 2 Or placebo GOOD GOOD NO CHANGE OR BAD NO CHANGE OR BAD
Why a TRIAL SERIES for one patient? EXAMPLES: Trial of different medications and/or placebo for child reported to have ADHD symptoms that are not clinically apparent Trial of different analgesics for patient with chronic pain from a combination of diseases not previously studied PATIENT •Must be blinded •Must keep diary or complete questionnaire PHYSICIAN •May need to be blinded (enlist help of pharmacist!) •Must treat patient as usual in all other respects BENEFIT Produces data most applicable to the individual patient
Intervention A ONE GROUP, MULTIPLE TESTS CROSSOVER TRIALS Intervention B Intervention B Intervention A ASSESS OUTCOMES #1 ASSESS OUTCOMES #2 COMPARE OUTCOMES (Best if participants are blinded)
Intervention A CROSSOVER TRIALS Intervention B Intervention B Intervention A ASSESS OUTCOMES #1 ASSESS OUTCOMES #2 Fewer participants needed than a RCT! Lower costsAll are in experimental group PROS & CONSPROS & CONS
Intervention A CROSSOVER TRIALS Intervention B Intervention B Intervention A ASSESS OUTCOMES #1 ASSESS OUTCOMES #2 MUST HAVE SHORT CARRYOVER EFFECTMUST HAVE SHORT CARRYOVER EFFECT MUST HAVE SHORT WASHOUT EFFECTMUST HAVE SHORT WASHOUT EFFECT (OR WAIT A SUITABLY LONG WASHOUT TIME!)(OR WAIT A SUITABLY LONG WASHOUT TIME!) PROS & CONSPROS & CONS
CASE CONTROL Present RISK FACTOR? (PAST) (“A LOOK BACK”)
CASE CONTROL Present NEVER SMOKED (PAST) (“A LOOK BACK”) SMOKER LUNG CANCER HEALTHY RISK FACTOR
CASE CONTROL Present NORMAL WEIGHT (“A LOOK BACK”) OBESITY DM TYPE II NON-DIABETIC RISK FACTOR
COHORT IS RISK FACTOR PRESENT? Future Outcome “FOLLOWUP DESIGN” (Exclude those with outcome already!)
COHORT IS RISK FACTOR PRESENT? Future Outcome “FOLLOWUP DESIGN” Present TO INVESTIGATE ETIOLOGY OR HYPOTHETICAL CAUSE OF DISEASE/OUTCOME
COHORT Present RISK FACTOR Hgb <9 EXAMPLE DIALYSIS PATIENTS Measures future outcome for dialysis pts w/o treatment of anemia
CROSS SECTIONAL DESIGN ? Cause ? Risk factors A look back
CROSS SECTIONAL DESIGN INFANT DEATHSSIDS DEATHS OTHER CAUSES RISK = SLEEP PRONE
NO CONTROL OVER CONTROL GROUP VARIATION IN TREATMENT OR METHOD NON-SIMILAR CONDITIONS Social Personal Comorbid conditions Other treatments Etc. Not usually accepted by medical journals (accepted in popular press, not reviewed) CURRENT GROUP OF PATIENTS Problems of looking back
RANDOMIZED & CONTROLLED TRIAL (RCT)RANDOMIZED & CONTROLLED TRIAL (RCT) Experimental Intervention Control Group PROSPECTIVEPROSPECTIVE MAY BEMAY BE BLINDEDBLINDED
START WITH YOUR TARGET POPULATION
START WITH YOUR TARGET POPULATION Set CRITERIA forSet CRITERIA for INCLUSION / EXCLUSIONINCLUSION / EXCLUSION This will determine:This will determine: ELIGIBILITYELIGIBILITY at the startat the start VALIDITYVALIDITY at the endat the end
START WITH YOUR TARGET POPULATION
ELIMINATE THOSE WHO DO NOT MEET THE CRITERIAELIMINATE THOSE WHO DO NOT MEET THE CRITERIA
NEXT: GATHER A SAMPLE GROUP
THE SAMPLE GROUP WILLTHE SAMPLE GROUP WILL:: •Represent the target populationRepresent the target population •Meet the criteria for inclusion / exclusionMeet the criteria for inclusion / exclusion SIDE NOTES…SIDE NOTES… Study should be approved by anStudy should be approved by an Ethics CommitteeEthics Committee Informed consent should beInformed consent should be obtained from study participantsobtained from study participants
SAMPLE GROUPSAMPLE GROUP MAYMAY BE SUBDIVIDED FURTHERBE SUBDIVIDED FURTHER STRATIFICATIONSTRATIFICATION Divide into subgroups based onDivide into subgroups based on important similar characteristicsimportant similar characteristics RANDOMIZATIONRANDOMIZATION Divide into sub-groups based onDivide into sub-groups based on unknown confoundersunknown confounders
STRATIFICATIONSTRATIFICATION ““important similar characteristics”important similar characteristics” Examples: • Male or Female • Age • Stage of illness • Prior illness or treatment • Hospital vs Office groups • Comorbid condition • Etc.
EXAMPLE OF STRATIFICATIONSTRATIFICATION FEMALE MALE
RANDOMIZATIONRANDOMIZATION ““unknown confounders”unknown confounders” Examples:Examples: • Postal codePostal code • Month of birthMonth of birth • Random numberRandom number • Etc.Etc.
EXAMPLE OF RANDOMIZATIONRANDOMIZATION DX IN JANUARY-JUNE DX IN JULY-DECEMBER
Experimental Intervention Control Group Next… Divide your sample group(s) intoDivide your sample group(s) into STUDY GROUPSSTUDY GROUPS ““Test Group”Test Group” ““Baseline Group”Baseline Group”
Experimental Intervention Control Group Next… Divide your sample group(s) intoDivide your sample group(s) into STUDY GROUPSSTUDY GROUPS Receives ExperimentalReceives Experimental InterventionIntervention ““Baseline GroupBaseline Group”” • NothingNothing • ObservationObservation • ““Same” miscellaneousSame” miscellaneous intervention (non-intervention (non- experimental)experimental) • PlaceboPlacebo • ““Gold Standard” therapy -Gold Standard” therapy - especially if unethical to doespecially if unethical to do otherwise!otherwise! ““Test GroupTest Group””
ASSIGN PATIENTS TO STUDY GROUPS Experimental Intervention Control Group Use caution against bias! Sample Group Study Groups
Experimental Intervention Control Group STUDY INVESTIGATOR  usually assigns patients to study groups.  usually has a personal preference for the treatment or patient  might unconsciously “work harder” to make the study work with non-preferred candidates = POTENTIAL FOR BIAS
Experimental Intervention Control Group Use random separation and assignment! RANDOMIZED CONTROLLED TRIAL (RCT)RANDOMIZED CONTROLLED TRIAL (RCT)
Experimental Intervention Control Group RANDOMIZEDRANDOMIZED CONTROLLEDCONTROLLED TRIAL (RCT)TRIAL (RCT)
RANDOMIZED CONTROLLED TRIAL (RCT)RANDOMIZED CONTROLLED TRIAL (RCT) Experimental Intervention Control Group FUTUREFUTURE PresentProceed with study
Experimental Intervention Control Group RANDOMIZED CONTROLLED TRIAL (RCT)RANDOMIZED CONTROLLED TRIAL (RCT) EXPERIMENTAL EVENT RATE (EER) CONTROL EVENT RATE (CER)
Experimental Intervention Control Group FUTURE Present RANDOMIZED CONTROLLED TRIAL (RCT)RANDOMIZED CONTROLLED TRIAL (RCT) EXPERIMENTAL EVENT RATE (EER) CONTROL EVENT RATE (CER) ““The GoldThe Gold Standard”Standard”
Disadvantages of RCT Expensive large # pts needed Prolonged recruitment and follow-up time needed Funding difficult to obtain except w/support of pharmaceutical companies (problematic!)
RETURN FROM DETOUR
THE FIVE BASIC STEPS OF EBM 1. Clinical Question Patient-focused, problem-oriented 2. Find Best Evidence Literary Search 3. Critical Appraisal Evaluate evidence for quality and usefulness 4. Apply the Evidence Implement useful findings in clinical practice 5. Evaluate The information, intervention, and EBM process
Interpreting the evidenceInterpreting the evidence • How to read a paperHow to read a paper • How to do the mathHow to do the math CRITICAL APPRAISALCRITICAL APPRAISAL
EVALUATE WRITTEN EVIDENCE FOR… Quality Usefulness …BY ASSESSING Validity Reliability Relevance Clinical importance
Critical Appraisal: VALIDITYCritical Appraisal: VALIDITY What was the original purpose of the studyWhat was the original purpose of the study?? When was it preparedWhen was it prepared?? By whomBy whom?? • credentials?credentials? • affiliations?affiliations? Sample populationSample population Did the subjects represent an appropriate test group? How were they selected? Were controls used? Were groups similar for important prognostic characteristics?
VALIDITYVALIDITY How was the information gathered and processed?How was the information gathered and processed? Were groups treated equally except for trial therapy? Were appropriate criteria used to measure results? Were criteria applied rigorously? Was the study completed?Was the study completed? (Or ended early for a specified reason?) Did the study account for all test subjectsDid the study account for all test subjects?? Including subjects lost to follow-up? Were ALL pts analyzed in their allocated groups? (ie: INTENTION TO TREAT - not “completed treatment” analysis)
VALIDITYVALIDITY InformationInformation Does the paper support its claims? Is the information accurately presented? Does it represent the truth? ResultsResults Are the results believable? To what degree of confidence? Ex: Disagreement is not uncommon on angiograms, EKGs, radiographs, pathology, PAP tests, etc.
VALIDITYVALIDITY ComprehensivenessComprehensiveness Size: Was it large enough to yield credible results? Thoroughness: Was it complete enough? Duration: Was it long enough?
CRITICAL APPRAISAL:CRITICAL APPRAISAL: RELIABILITY Do we trust the information and results? 1. APPROPRIATE TYPE OF STUDY 2. REPRODUCEABILITY 3. INTERPRETATION OF RESULTS 4. BIAS
RELIABILITY APPROPRIATE TYPE OF STUDY Was the type of study design used proper for the question?Was the type of study design used proper for the question? Example: RCT would be choice for questions on TREATMENT
RELIABILITY Are the Measurements and Results reproducibile? Different determinations may be caused by: • Variation in measurement methods • Different interpretation of results • Lack of agreement Example: BP checks on same patient may vary. Are differences result of pt factor, examiner factor, treatment factor, normal variance Would the same results be obtained if patient is re-measured? (with identical procedure) • at another time? • by another person? Were any similar studies done? • Was the information comparable? • Did the results agree?
RELIABILITY INTERPRETATION OF RESULTS Is there consistency among researchers?Is there consistency among researchers? Different determinations may be caused by: • Variation in measurement methods • Different interpretation of results • Lack of agreement EXAMPLE: BANFF CONFERENCE - Setting standards in Transplant Pathology established by Kim Solez, MD Were any new questions or controversies raised by the study?Were any new questions or controversies raised by the study?
RELIABILITYRELIABILITY IS THERE ANY EVIDENCE OF BIASIS THERE ANY EVIDENCE OF BIAS?? A dangerous pitfall!A dangerous pitfall! • PATIENTSPATIENTS • RESEARCHERSRESEARCHERS
PATIENT BIASPATIENT BIAS Social Desirability BiasSocial Desirability Bias Patient responds in the wayPatient responds in the way they perceive as correctthey perceive as correct • to support MDto support MD • to support a preconceivedto support a preconceived notion (ie: foods vs ADD)notion (ie: foods vs ADD) Patient denies unhealthyPatient denies unhealthy behavior, gets misclassifiedbehavior, gets misclassified Ex: Smoker vs Non-smokerEx: Smoker vs Non-smoker
PATIENT BIASPATIENT BIAS Hawthorne EffectHawthorne Effect AuthorsAuthors mustmust take steps totake steps to reduce this bias by treatingreduce this bias by treating all equally!all equally! Ex: Weigh all patients with sameEx: Weigh all patients with same frequency, even for group not onfrequency, even for group not on special dietspecial diet People act differently whenPeople act differently when they know they are beingthey know they are being watched.watched. Ex: Follow more careful dietEx: Follow more careful diet when regular weigh-ins arewhen regular weigh-ins are scheduledscheduled
RESEARCHER BIAS Who sponsored or funded the study? Personal gain or loss from results? Affiliates Special interests Conflict of interest Biased goal? To satisfy editors and reviewers… rather than solve real life clinical problems
Criteria bias? Risk-avoidance by researchers (will focus energy on topics that produce positive results) Bias toward patients? Sample selection criteria used (inclusive, exclusive) Assignment to test group or control - Random? Blind? RESEARCHER BIAS
Data collection methods used • applied similarly to all subjects, including controls? • starting point – prospective/retrospective, stage of patient? • Was assessment blind? Data analysis • Were all potential subjects included in denominator or otherwise accounted? • Were they evaluated in originally designated group? (INTENTION TO TREAT) RESEARCHER BIAS
REDUCING OR ELIMINATING BIAS AND ERROR CONDUCT BLIND STUDIES • Single • Double-blinded USE INDEPENDENT OBSERVERS • When doctor and/or patient can not be blinded, blinded IO measures outcome • IO may even be unaware of study hypothesis USE MULTIPLE OBSERVERS Ex: Send subject slides to multiple pathologists for interpretation ESTABLISH CLEAR STANDARDS • Exact methods to use to reduce variation in technique among researchers • Clear wording on surveys, etc VALIDATING INSTRUMENTS • Repeat screening to check for correct answers on surveys • More frequent evaluations or surveys prevent guesstimates common to less frequent evaluation
NEXT STEP IN CRITICAL APPRAISAL:NEXT STEP IN CRITICAL APPRAISAL: RELEVANCERELEVANCE QUESTION: Is the report applicable to our…QUESTION: Is the report applicable to our… Problem?Problem? ““Does it address the questions raised?”Does it address the questions raised?” Patient(s)?Patient(s)? ““Will my patient respond like those in the study?”Will my patient respond like those in the study?” Practice?Practice? ““Can it be done within my practice or circle?”Can it be done within my practice or circle?”
ARE THE STUDY PATIENTS • Comparable within the study? (similar traits, age, socioeconomic group, stage of illness, treatment, etc.) • Comparable to your patient? ARE THE STUDY PROFESSIONALS • Comparable to you? (general/specialist, primary care/teaching hospital, etc.)
NEXT STEP in CRITICAL APPRAISALNEXT STEP in CRITICAL APPRAISAL CLINICAL IMPORTANCECLINICAL IMPORTANCE Information can be true and interesting in theory,Information can be true and interesting in theory, yetyet uselessuseless in clinical practice!in clinical practice! 1.1. Is the information clinically important?Is the information clinically important? 2.2. If yes, how important is it?If yes, how important is it? • study design - See: Hierarchy of Evidencestudy design - See: Hierarchy of Evidence • weight of resultsweight of results
HEIERARCHY OF EVIDENCEHEIERARCHY OF EVIDENCE (value of study design to maximize wt, minimize bias)(value of study design to maximize wt, minimize bias) 1. Systematic Review of all relevant RCTs 2. At least one properly designed RCT 3. Trials and case studies 4. Well-designed Controlled Trial without Randomization 5. Well designed Cohort or Case Control Studies, preferably from >1 centre or group 6. Multiple Time series with or without intervention 7. (Exception: Dramatic results in uncontrolled trials, such as introduction of PCN in the 1940s) 8. Opinions of respected authorities, based on 9. Clinical expertise 10. Descriptive studies 11. Reports of Expert Committees
RANDOMIZEDRANDOMIZED CONTROLLED TRIAL (RCT)CONTROLLED TRIAL (RCT) Evaluation of RCT Were all clinically appropriate outcomes measured? Did an ethics committee approve the study? Any statistically significant results also clinically significant? Any significant adverse reactions? Was follow-up procedural analysis identical? Was continuous data analysis vs end of trial data used?
Interpreting the evidenceInterpreting the evidence • How to read a paperHow to read a paper • How to do the mathHow to do the math
HOW TO DO THE MATH Incidence Prevalence Statistical Formulas +/- Predictive Values - Probability - The p value Relative Risk Risk Reduction Odds Ratios NNT (Number Needed to Treat) – Risk Reduction Confidence Intervals Sensitivity and Specificity Regression Analysis Subgroup Analysis Health Status Evaluation Health Economics
ACCOUNT FOR ALL even if •Non-compliant •Lost to follow-up Analyze as a member of the originally assigned group! Analysis SHOULD BE BASED ON • INTENTION TO TREAT • NOT on “completed treatment” analysis OUTCOMES: NOT “STUDY FAILURES” OUTCOMES RELATE TO EVERYDAY CLINICAL PRACTICE, including… • Deaths • Poor compliance • Wrong treatment received • Lost to follow-up • Etc.
INCIDENCE & PREVALENCE NEPHROL, a service of NKF cyberNephrology 7/10/03 10:17:12AM Dear Nephrolers, I would like to know how to calculate incidence and prevalence of B and C virus in HD. Thank you in advance. Mario Cuba, MD Servicio de Nefrologia Hospital Lucia Iniguez Landin Holguin, Cuba
INCIDENCE & PREVALENCE Response from Michel Jadoul, MD NEPHROL, a service of NKF cyberNephrology Prevalence: total number of positive patients divided by total number of patients: 20+/200=10% Incidence: number of new positive cases/total number of cases negative at start of period (e.g; year)/period (year?) thus : for instance 2 new positive cases /100 negative cases at start of year=2%/year. M.Jadoul, M.D.
PREVALENCE BB BB BB BB BB BB BB BB BB BB 10 cases Hep B in 100 patients 10 / 100 = 0.10 PREVALENCE = 10%
INCIDENCE BB BB BB BB BB BB BB BB BB BB BB BB BB BBBB 1 year period 90 HBsA(-) at start of study 5 new cases 5 / 90 = 0.06 INCIDENCE = 6% per year
BB BB BB BB BB BB BB BB BB BB BB BB BB BBBB RECALCULATED PREVALENCE 16 cases Hep B in 100 patients 16 / 100 = 0.16 NEW PREVALENCE = 16%NEW PREVALENCE = 16%
COMPARISON STUDIES: NEW DIAGNOSTIC TESTS RESULTS OF GOLD STANDARD TEST EXPERIMENTALTEST POSITIVE NEGATIVE DISEASE PRESENT NO DISEASE TRUE (+) a FALSE (+) b FALSE (-) c TRUE (-) d COMPARING A NEW TEST AGAINST THE GOLD STANDARD TEST
ACCURACY OF TEST - COMPARE TO GOLD STANDARD What is the usefulness of the test in various groups and subgroups of pts? RESULTS OF GOLD STANDARD TEST EXPERIMENTALTEST TEST POSITIVE a + b TEST NEGATIVE c + d DISEASE PRESENT a + c NO DISEASE PRESENT b + d TRUE (+) a FALSE (+) b FALSE (-) c TRUE (-) d TESTS ARE RARELY 100% ACCURATE THEY MUST BE COMPARED AGAINST THE GOLD STANDARD
ACCURACY OF TEST - COMPARE TO GOLD STANDARD What is the usefulness of the test in various groups and subgroups of pts? RESULTS OF GOLD STANDARD TEST EXPERIMENTAL TEST TEST POSITIVE TEST NEGATIVE DISEASE PRESENT DISEASE NOT PRESENT TRUE (+) a FALSE (+) b FALSE (-) c TRUE (-) d TESTS ARE RARELY 100% ACCURATE THEY MUST BE COMPARED AGAINST THE GOLD STANDARD TOTALS c + d a + b TOTALS a+b+c+db + da + c
ACCURACY OF TEST - COMPARE TO GOLD STANDARD What is the usefulness of the test in various groups and subgroups of pts? RESULTS OF GOLD STANDARD TEST EXPERIMENTAL TEST TEST POSITIVE TEST NEGATIVE DISEASE PRESENT DISEASE NOT PRESENT TRUE (+) a FALSE (+) b FALSE (-) c TRUE (-) d TESTS ARE RARELY 100% ACCURATE THEY MUST BE COMPARED AGAINST THE GOLD STANDARD TOTALS c + d a + b TOTALS a+b+c+db + da + c SENSITIVITY SPECIFICITY
SENSITIVITY AND SPECIFICITY SENSITIVITY = PATIENT (+) TEST (+) Probability that patient WITH disease will have ABNORMAL result (instead of False Negative) SPECIFICITY = PATIENT (-) TEST (-) Probability that patient WITHOUT disease will have NORMAL result (instead of False Positive) OVERALL DISCRIMINATION OF TESTS High SENSITIVITY = low number false negatives High SPECIFICITY = low number of false positives Best accuracy if both factors are close to 100%
SENSITIVITY = a / (a + c) PATIENT (+) TEST (+) SPECIFICITY = d / (b + d) PATIENT (-) TEST (-) POSITIVE PREDICTIVE VALUE = a / (a + b) If pt tests (+), what is the likelihood s/he has the disease? NEGATIVE PREDICTIVE VALUE = d / (c + d) If pt tests (-), what is the likelihood s/he does NOT have the disease? PREVALENCE = (a + c) / (a + b + c + d) ACCURACY = (a + d) / (a + b + c + d) Proportion of results that correctly identify pts with and without disease (True + and True - as proportion of all results) LIKELIHOOD RATIO = sensitivity / (1 - specificity) How likely is it that + result accurately indicates disease, and - result no disease?
LIKELIHOOD RATIO (LR) Because Sensitivity and Specificity are NOT always 100% How likely is it that + result accurately indicates disease, and - result no disease? LIKELIHOOD RATIO FOR A POSITIVE RESULT (LR+) Probability of (+) result in diseased subject divided by Probability of (+) result in a healthy subject - or worded differently - Sensitivity divided by 100% - Specificity LIKELIHOOD RATIO FOR A NEGATIVE RESULT (LR-) 100% - Sensitivity divided by Specificity DISCRIMINATION = ZERO IF LR = 1
EVALUATING STUDY RESULTSEVALUATING STUDY RESULTS Example: Mortality rates in 4444 pts x 5.4 trial years: 11.5% Placebo 8.2% Medicine RRR 29% (Relative Risk Reduction) ARR 3.3% (Absolute Risk Reduction) NNT 30 (Number needed to treat for 5.4 years to save 1 life
QALY = QUALITY ADJUSTED LIFE YEARQALY = QUALITY ADJUSTED LIFE YEAR QUALITY RATING NOT specific for disease or treatment! Value rating - subject to different values of patients, physician, community • Patient-based • Economy-based - cost-utility/cost-effectiveness analysis Compares outcomes of conditions or intervention(s) • State of health - vs -Time spent in it
QUALY: QUALITY ADJUSTED LIFE YEAR 0 2 4 6 8 10 1 2 3 4 5 5-yrTREATMENT COMPARISON Chemo&Rad Radiation only Chemo only 1 2 3 4 5 6 7 8 9 10 2 3 4 5 6 7 8 9 10 PERFECT HEALTH 1 2 3 4 5 6 7 8 9 10 2 3 4 5 6 7 8 9 10 CHRONIC MEDIOCRITY 0 1 2 3 4 5 6 7 8 9 2 3 4 5 6 7 8 9 10 DETERIORATING HEALTH
TEST RESULTS: VARIABILITY FACTFACT: Study results may vary.: Study results may vary. Group too small Not representative of larger group Etc. Age, sex, race, condition, culture, etc. Compliancy issues (patient and physician!) May be discovered or identified through study
TEST RESULTS: VARIABILITY FACTFACT:: Variability may or may not be significantVariability may or may not be significant Group too small Not representative of larger group Etc. Age, sex, race, condition, culture, etc. Compliancy issues (patient and physician!) May be discovered or identified through study
TEST RESULTS: VARIABILITY Group too small Not representative of larger group Etc. Age, sex, race, condition, culture, etc. Compliancy issues (patient and physician!) May be discovered or identified through study Obviously faulty studies should be eliminated.Obviously faulty studies should be eliminated.
TEST RESULTS: VARIABILITY Group too small Not representative of larger group Etc. Age, sex, race, condition, culture, etc. Compliancy issues (patient and physician!) May be discovered or identified through study Some variability should be expected in the rest.Some variability should be expected in the rest.
TEST RESULTS: VARIABILITY Group too small Not representative of larger group Etc. Age, sex, race, condition, culture, etc. Compliancy issues (patient and physician!) May be discovered or identified through study Some factors are completely unexpected.Some factors are completely unexpected.
and variability due toand variability due to The statistics allow us to distinguish betweenThe statistics allow us to distinguish between
PROBABILITYPROBABILITY CHANCECHANCE WARNING PROBABILITY should NOT be confused with CHANCE! Statistically significant Results are measurable and predictable Affected by sample size (1 in 20 is less convincing than 1 in 10,000) No statistical significance Random, unpredictable
A Study in Probability… QUESTION #1QUESTION #1:: What percentage of patients will develop diarrhea whileWhat percentage of patients will develop diarrhea while taking Antibiotic A?taking Antibiotic A? QUESTION #2QUESTION #2:: Will the results be the same, better or worse onWill the results be the same, better or worse on Antibiotic B?Antibiotic B? PROBABILITYPROBABILITY
50 50 50 50 50 50 50 50 50 50 5050 50 5050 50 50 50 50 50 20 study groups 50 pts each study 1000 patients total QUESTION #1QUESTION #1:: What percentage of patients will develop diarrhea whileWhat percentage of patients will develop diarrhea while taking Antibiotic A?taking Antibiotic A?
4 6 108 12 14 16% Conduct studies Organize results NUMBEROFSTUDIES PERCENTAGE OF PATIENTS WITH DIARRHEA QUESTION #1QUESTION #1:: What percentage of patients will develop diarrhea whileWhat percentage of patients will develop diarrhea while taking Antibiotic A?taking Antibiotic A?
4 6 108 12 14 16% NUMBEROFSTUDIES PERCENTAGE OF PATIENTS WITH DIARRHEA IDENTIFY STATISTICALLY SIGNIFICANT RESULTS The Bell CurveThe Bell Curve
Most COMMONCOMMON result = 4 6 108 12 14 16% MODEMODENUMBEROFSTUDIES PERCENTAGE OF PATIENTS WITH DIARRHEA
The CENTERCENTER of distribution = 4% 6 8 12 14 16% MEDIANMEDIANNUMBEROFSTUDIES PERCENTAGE OF PATIENTS WITH DIARRHEA 10
MODEMODE (most COMMONCOMMON result) = 10%10% MEDIANMEDIAN (the CENTERCENTER of distribution) = 10%10% NUMBEROFSTUDIES PERCENTAGE OF PATIENTS WITH DIARRHEA DETERMINE RESULTS OF STUDYDETERMINE RESULTS OF STUDY 4 6 108 12 14 16%
““10% of patients will develop diarrhea while10% of patients will develop diarrhea while taking Antibiotic A.”taking Antibiotic A.” NUMBEROFSTUDIES PERCENTAGE OF PATIENTS WITH DIARRHEA 104 6 8 12 14 16% CONCLUSION
4 6 8 12 14 16 NUMBEROFSTUDIES PERCENTAGE OF PATIENTS WITH DIARRHEA Wait… What about the other 15 study groups? You can’t just ignore them! 10 Or can you?
4 6 8 12 14 16 PERCENTAGE OF PATIENTS WITH DIARRHEA Wait… What about the other 15 study groups? You can’t just ignore them! 10 Or can you? 15 groups x 50 per group = 750 patients (75%!)
4 6 8 12 14 16 PERCENTAGE OF PATIENTS WITH DIARRHEA Wait… What about the other 15 study groups? You can’t just ignore them! 10 Or can you? Studies must account for ALL patients
4 6 8 12 14 16 NUMBEROFSTUDIES PERCENTAGE OF PATIENTS WITH DIARRHEA Wait… What about the other 15 study groups? You can’t just ignore them! 10 Or can you? Results should not be ignored, but STATISTICAL SIGNIFICANCE may be questioned.
NUMBEROFSTUDIES PERCENTAGE OF PATIENTS WITH DIARRHEA 4 6 8 12 14 1610 My head is starting to feel heavy… So, how is STATISTICAL SIGNIFICANCE determined?
PROBABILITY is determined by it. CHANCE is not related to it at all! STATISTICAL SIGNIFICANCESTATISTICAL SIGNIFICANCE How is it determined?How is it determined?
PERCENTAGE OF PATIENTS WITH DIARRHEA Let’s use our study on “Antibiotic A” as the exampleLet’s use our study on “Antibiotic A” as the example 4 6 8 12 14 16%10 NUMBEROFSTUDIES 20 groups were tested.20 groups were tested. Only 1 of 20 groups landed at each end of the Bell Curve….Only 1 of 20 groups landed at each end of the Bell Curve…. WHY?WHY? SAMPLESAMPLE VARIATION?VARIATION? or CHANCE?or CHANCE?
PERCENTAGE OF PATIENTS WITH DIARRHEA ““There is aThere is a 1 in 20 chance1 in 20 chance that other patientsthat other patients will land in these categories.”will land in these categories.” But thatBut that wouldwould NOTNOT be a correctbe a correct statement!statement! It is tempting to say,It is tempting to say, 4 6 8 12 14 16%10 NUMBEROFSTUDIES
PERCENTAGE OF PATIENTS WITH DIARRHEA ““There is aThere is a 1 in 20 chance1 in 20 chance that other patientsthat other patients will land in these categories.”will land in these categories.” Why?Why? BecauseBecause CHANCECHANCE can not becan not be used toused to predictpredict futurefuture results!results! It is tempting to say,It is tempting to say, 4 6 8 12 14 16%10 NUMBEROFSTUDIES
CHANCECHANCE is based onis based on RANDOMRANDOM possibility.possibility. Example:Example: THE COIN TOSSTHE COIN TOSS Coins tossed: 20 “Heads” 17 (85%) “Tails” 3 (15%) Statistical SignificanceStatistical Significance:: ZERO!ZERO! The next coin toss will still produce a random result!The next coin toss will still produce a random result! Random results can not be used to calculate Statistical Probability.
4% 6 8 12 14 16%10 ““There is aThere is a 1 in 20 chance1 in 20 chance that patients willthat patients will land in one of these two categories.”land in one of these two categories.” So instead of measuring “chance”…So instead of measuring “chance”… PERCENTAGE OF PATIENTS WITH DIARRHEA 1 in 201 in 20 chancechance 1 in 201 in 20 chancechance
4% 6 8 12 14 16%10 We need to determine theWe need to determine the PROBABILITY!PROBABILITY! 1 in 201 in 20 chancechance Translates into 5%5% probabilityprobability PERCENTAGE OF PATIENTS WITH DIARRHEA ““There is aThere is a 5% probability5% probability that patients willthat patients will land in one of these two categories.”land in one of these two categories.”
4% 6 8 12 14 16% There is aThere is a 5% probability5% probability that 4% ofthat 4% of patients willpatients will developdevelop diarrhea ondiarrhea on Antibiotic A.Antibiotic A. There is aThere is a 5% probability5% probability that 16%ofthat 16%of patients willpatients will developdevelop diarrhea ondiarrhea on Antibiotic A.Antibiotic A. 10 PERCENTAGE OF PATIENTS WITH DIARRHEA The results now look like this:The results now look like this:
4% 6 8 12 14 16%10 1 in 201 in 20 chancechance ProbabilityProbability == 5%5% PERCENTAGE OF PATIENTS WITH DIARRHEA FRACTIONFRACTION PERCENTAGEPERCENTAGE And now… Let’s abbreviate it some more!And now… Let’s abbreviate it some more! p = 0.05p = 0.05 Translates to DECIMELDECIMEL
4% 6 8 12 14 16%10 1 in 201 in 20 chancechance PERCENTAGE OF PATIENTS WITH DIARRHEA FRACTIONFRACTION PERCENTAGEPERCENTAGE p = 0.05p = 0.05 Translates to DECIMELDECIMEL ……by changing “by changing “% probability% probability” to” to the “the “p valuep value”” ProbabilityProbability == 5%5%
4% 6 8 12 14 16%10 1 in 201 in 20 chancechance PERCENTAGE OF PATIENTS WITH DIARRHEA p = 0.05p = 0.05 Translates to FRACTIONFRACTION DECIMELDECIMEL PERCENTAGEPERCENTAGE The “The “p valuep value” is statistically important!” is statistically important! ProbabilityProbability == 5%5%
4% 6 8 12 14 16%10 1 in 20 “chance” p = 0.05p = 0.05 It determines statistical PROBABILITY.It determines statistical PROBABILITY. ““p value”p value” ProbabilityProbability == 5%5%
4% 6 8 12 14 16%10 PROBABILITY vs CHANCEPROBABILITY vs CHANCE ……bbut PROBABILITYPROBABILITY is very important! It tells us the likelihood that something will happen. So, CHANCECHANCE has ZERO significance PERCENTAGE OF PATIENTS WITH DIARRHEA NUMBEROFSTUDIES
““There is aThere is a 5% probability5% probability that our study patientsthat our study patients will fall into either of these categories.”will fall into either of these categories.” OUR PROBABILITY STATEMENTOUR PROBABILITY STATEMENT p = 0.05p = 0.05 p = 0.05p = 0.05 PERCENTAGE OF PATIENTS WITH DIARRHEA 4 6 108 12 14 16%
Anything less than 5% (p= 0.05)Anything less than 5% (p= 0.05) MAYMAY be due to chance.be due to chance. THAT IS A LOW PROBABILITY!THAT IS A LOW PROBABILITY! p = 0.05p = 0.05 p = 0.05p = 0.05 PERCENTAGE OF PATIENTS WITH DIARRHEA 4 6 108 12 14 16%
4 6 108 12 14 16% p = 0.01p = 0.01p = 0.01p = 0.01 And anything less than 1% (p= 0.01)And anything less than 1% (p= 0.01) isis MOST LIKELYMOST LIKELY due to chance!due to chance! THAT IS A LOW PROBABILITY!THAT IS A LOW PROBABILITY!
Anything less than 5% (p= 0.05)(p= 0.05) MAY be due to chance. THAT IS A LOW PROBABILITY!THAT IS A LOW PROBABILITY! 4 6 108 12 14 16% p = 0.01p = 0.01p = 0.01p = 0.01 Anything less than 1% (p= 0.01)(p= 0.01) is MOST LIKELY due to chance. p = 0.05p = 0.05 p = 0.05p = 0.05
(p= 0.05)(p= 0.05) becomesbecomes VERY SIGNIFICANTVERY SIGNIFICANT But when compared to another study…But when compared to another study… 4 6 108 12 14 16 And (p= 0.01) becomesAnd (p= 0.01) becomes HIGHLY SIGNIFICANTHIGHLY SIGNIFICANT!! 18%
(p= 0.05)(p= 0.05) becomesbecomes VERY SIGNIFICANTVERY SIGNIFICANT But when compared to another study…But when compared to another study… 4 6 108 12 14 16 And (p= 0.01) becomesAnd (p= 0.01) becomes HIGHLY SIGNIFICANTHIGHLY SIGNIFICANT!! 18%
4% 6 108 12 14 16 Antibiotic AAntibiotic A NUMBEROFSTUDIES PERCENTAGE OF PATIENTS WITH DIARRHEA 18%
4% 6 108 12 14 16 Antibiotic BAntibiotic B NUMBEROFSTUDIES PERCENTAGE OF PATIENTS WITH DIARRHEA 18%
(p= 0.05)(p= 0.05) becomesbecomes VERY SIGNIFICANTVERY SIGNIFICANT DIFFERENCE = STATISTICALLY SIGNIFICANTDIFFERENCE = STATISTICALLY SIGNIFICANT 4 6 108 12 14 16 And (p= 0.01) becomesAnd (p= 0.01) becomes HIGHLY SIGNIFICANTHIGHLY SIGNIFICANT!! 18%
The P valueThe P value Measures ProbabilityMeasures Probability How often is this finding expected to occur? Determines Statistical SignificanceDetermines Statistical Significance What is the likelihood these findings are TRUE or FALSE? Do the comparative findings show a significant difference? Meaningful ranges p >0.05 Not significant p <0.05 Statistically SIGNIFICANT p <0.01 HIGHLY SIGNIFICANT! Does probability provide PROOF?Does probability provide PROOF? NO! We could be misled by it. The sample size is very important when determining probability!
SAMPLE SIZE and PROBABILITYSAMPLE SIZE and PROBABILITY EXAMPLE: 100 pieces of fruit are in a bin: APPLES and ORANGES You close your eyes and pick 10 of them: Question: Does your sample accurately represent what is in the bin?
Answer: No! Larger samples provide a closer approximation of theLarger samples provide a closer approximation of the populations they represent... But the only way to getpopulations they represent... But the only way to get 100% proof is to examine “all of the fruit in the bin!”100% proof is to examine “all of the fruit in the bin!”
The P valueThe P value Meaningful ranges p >0.05 Not significant p <0.05 Statistically SIGNIFICANT* p <0.01 HIGHLY SIGNIFICANT!** *Significance only means that CHANCE is an unlikely explanation for the results LIMITATIONLIMITATION The p value determines LIKELIHOOD… Not proof!The p value determines LIKELIHOOD… Not proof! CAUTIONCAUTION Statistical significance does not necessarily imply anyStatistical significance does not necessarily imply any clinicalclinical significance!significance! EXAMPLE: Looking through a pinhole will improve vision in most people… But would this be an appropriate treatment for your myopic patients? (Key Topics in EBM )
MISCELLANEOUS STUFF
THE FIVE BASIC STEPS OF EBM 1. Clinical Question Patient-focused, problem-oriented 2. Find Best Evidence Literary Search 3. Critical Appraisal Evaluate evidence for quality and usefulness 4. Apply the Evidence Implement useful findings in clinical practice 5. Evaluate The information, intervention, and EBM process
PATIENT PHYSICIAN INFORMATION Question or Problem (The Three Major Components of EBM)(The Three Major Components of EBM)
PATIENT PHYSICIAN INFORMATION
PATIENTPATIENT
PATIENTPATIENT ““A METHODOLOGICALA METHODOLOGICAL MINEFIELD”MINEFIELD”
PATIENT “A METHODOLOGICAL MINEFIELD” INFORMATION Difficult time understanding background information PHYSICIAN Personal priorities may conflict with yours
PATIENT Recognize: Needs Choices Preferences Values Socioeconomic concerns INFORMATION Help the patient to understand and interpret available information PHYSICIAN Respect the personal priorities of the patient Help the patient to negotiate a decision on intervention, treatment CONFLICT?CONFLICT? SEPARATE THE ISSUES!SEPARATE THE ISSUES!
PATIENT INFORMATIONPHYSICIAN PATIENT And then help theAnd then help the patient pull it allpatient pull it all together againtogether again
KEY POINTSKEY POINTS PARADIGM SHIFT OLD: Doctor had authority (despite the pile of unread journals!) NEW: Current Best Evidence leads medical practice but it MUST be individually applied THE INDIVIDUAL PATIENT Every patient is different. Treat YOURS and not others The “ideal” course of action is not necessarily best for THIS patient. EBM + Psychosocial factors = THIS patient should be advised to take THIS therapy at THIS point in time.
THE FIVE BASIC STEPS OF EBM 1. Clinical Question Patient-focused, problem-oriented 2. Find Best Evidence Literary Search 3. Critical Appraisal Evaluate evidence for quality and usefulness 4. Apply the Evidence Implement useful findings in clinical practice 5. Evaluate The information, intervention, and EBM process
INFORMATION Adequate resources? Ease or Difficulty of finding and getting desired information? Costs? INTERVENTION Patient response or acceptance? Ease or Difficulty of Application? Clinical outcomes? EBM PROCESS EFFECT ON PRACTICE Will this particular experience change our thinking or practice? SELF EVALUATION How did we do? (Question, Search, Appraise, Apply) How could we improve our own EBM performance? Evaluate
EBM: PROS, CONS and LIMITATIONS
PROS Clinicians update knowledge base routinely Improved understanding of research methods Physician becomes more critical in use of data Increased confidence in management decisions Increased computer literacy, data search technology Better reading habits Provides framework for group problem solving, team generated practice
Transforms weakness or paucity of knowledge into positive change OK to be uncertain OK to be skeptical OK to be flexible Integrates medical education, research and clinical expertise Can be learned by non-clinicians – other HCWs, patient groups, purchasers, etc. Allows us to keep up with our better-educated patients!
Increased contribution of junior MDs Increased patient benefit Better communication with patients re: rationale of management decisions Promotes better and more appropriate use of limited resources May reduce costs or medical care or practice by eliminating outdated or unnecessary factors Can be learned at any stage of physician’s career
CONS Time consuming Information overload Time to learn and practice Time may be needed for team conferencing, planning and review Takes $$$ to establish resource infrastructure – library, office, etc. computers, peripherals
Internet costs Programs, software information, CD-ROMS Subscription costs – online and paper resources May increase cost of care (but hopefully offset by elimination of unnecessary medical interventions, tests, journals, etc. – plus save time in getting proper intervention) Online references made to unavailable journals or references Exposes gaps in the evidence (but provides ideas for researchers!)
Requires computer skills (but can be done with minimal computer literacy and skill) May expose your current practice as obsolete or dangerous (loss of authority and respect)
LIMITATIONS Lack of evidence (shortage of studies) Difficulty applying evidence to care of a particular patient Barriers to the practice of high quality medicine Lack of skills (search, appraise, etc.) (foster development of new skills!) Lack of time to learn and practice EBM (promotes lifelong learning thru better focus) Lack of physician resources for instant access to evidence (EBM has worldwide applicability)
RESTRICTED AVAILABILITY OF LAB TESTS NON-TEXTBOOK CASE co morbidity, additional risk factors AFFORDABILITY (MD & PT)“I can’t afford to practice EBM.” Language barriers – available evidence may be unreadable, should be included
Physician attitude: Can be the greatest limitation! “It decreases the importance of my clinical expertise” (that’s a necessary component!) “It only applies to those involved in research.” (promotes cooperation among multiple physicians) “It ignores patient values and preferences.” “It’s just another cookbook approach to medicine.” “It’s a poorly disguised way to cut medical costs.” (cost of care may actually increase) “It’s a way to ration care and resources.” (Provides better utilization of avail resources)
DISAGREEMENT Pt’s comfort, choice, acceptance, values preferences Vs MD’s recommendations DOES RISK OR SIDE EFFECTS OF TREATMENT OUTWEIGHT THE BENEFITS?
The unanswered question… “DOES EBM REALLY MAKE A DIFFERENCE?” Effect of practicing EBM on patient outcome is actually unknown – no studies done EBM good based on population studies: (ie: Pts who rec’d ___ generally fare better than those who don’t)
EBM IN DEVELOPING COUNTRIES LIMITED RESOURCES May help to eliminate unnecessary or poor quality screening tests (ie: resting EKG to screen for CAD = high false negative and false positive rates) LIMITED DRUG REGULATION Approval for drug marketing easy - promotes insurgence of new drugs for questionable indications, limited effectiveness, false claims, inflated prices based on ad response (include “more expensive is better”)
EBM IN DEVELOPING COUNTRIES LIMITED CAPACITY FOR CME Drug companies - may sponsor meetings that are little more than captive marketing sessions or biased education sessions (drug education vs promo) Result may be push for more expensive, less effective treatments (ie push for CCB’s over BB’s) - calc channel blockers over Beta Blockers
EBM IN DEVELOPING COUNTRIES LIMITED ACCESS TO LITERATURE DATABASES Desktop computer with CD ROM reader and modem ($900) Electricity 1 yr subscription to MedLine on CD ROM (?500) Internet connection $25/mt Convince administrators of expense: Publicly cite how searches help with lectures, research and patient care management decisions Get equipment from drug companies (usually strings attached)
EBM IN DEVELOPING COUNTRIES LIMITED ACCESS TO ADEQUATE LIBRARY FACIILITIES ALMOST INEVITABLE IN DEVELOPING COUNTRIES Identify resources via search, but then unable to retrieve articles! A top EBM practitioner (Philippines) recommends: 1. Top 3 medical libraries in your country 2. Multinational drug company libraries 3. Friends and colleagues - including in other countries
EBM IN DEVELOPING COUNTRIES QUESTIONABLE APPLICABILITY OF ARTICLES RETRIEVED Article describes a treatment that worked in one country, but seems impossible in yours Check… • Are there pathophysiologic differences? • Will patient differences diminish the treatment response? • Patient compliance issues? • Provider compliance issues? • Co-morbid conditions which will alter the benefits or risks?
EBM IN DEVELOPING COUNTRIES OBSTACLES TO TEACHING OR LEARNING EBM Your Hospital or Institution does not reimburse for time spent on Continuing Medical Education programs The standard 5-day workshop would be far too costly to provide or attend! Need to learn the basics - computer skills, etc. TRY THESE! Combine efforts to learn more and practice EBM with handful of colleagues (small group learning) Ask about basis for information provided by drug reps, medical supply companies, etc. It will prompt them to provide you with on the spot teaching and better information, too!
EBM LIBRARY BASIC REQUIREMENTS Convenient – easy access at point of contact with patient if possible Current – Up to date information Electronic Database – Should be included • Online • CD-ROM
ELECTRONIC DATABASES Evidence-Based Medicine Reviews (EBMR) – from Ovid (ovid.com) - combines Cochrane, Best evidence, Evidence Based Mental health, EB Nursing, Cancerlit, healthstar, AIDSline, Medline, and journal links (Described by one EBM specialist as “the best”) Cochrane Library – “Gold Standard” for systematic reviews Best Evidence Medline – world’s largest, free resource – over 10 million references
PERSONNEL Medical Librarian Informatics Specialist “We can learn a great deal about current best information sources from librarians and other experts in medical informatics, and should seek hands-on training from them as an essential part of our clinical training.” (ch 2 p29-30 – Blue circled 2)
PRINTED RESOURCES TEXTBOOKS most obsolete! Some updated yearly, plus heavy references and scientific evidence for support Clinical Evidence (BMJ Publishing Group & ACP – 1999- present) Evidence-Based On Call (http//cebm.jr.ox.uk/eboc/eboc.html) Up To Date (General medicine, CD format, Medline abstracts used for evidence) Scientific American Medicine – limited references from Medline, Harrisons
JOURNALS Traditional Journals subject to author submissions specialists need to read and evaluate may subscribe to services that send articles of interest to your specialty timely, instant information at time of publication Ex: NEJM, Clinical Nephrology, etc. Evidence Based journals selects best studies from multiple journals of interest, summarizes best evidence Good for use by generalists Lag time from original publication: 3-6 months Ex: Evidence Based Medicine, Evidence Based Nursing, Evidence Based CV Medicine, etc.
SPECIAL RESOURCES WHO Blue trunk Hinari PATIENT RESOURCES Medical treatments www.nlm.nih.gov/medlineplus Medical guidelines www.guideline.gov
THE NEXT LEVEL: ADVANCED EBM SUMMARIZE AND STORE INFORMATION Future reference SHARING INFO Local Colleagues Author paper TEACHING New skills or treatments EBM practices OTHER APPLICATIONS Care of the individual patient Team protocols Hospital or practice guidelines
EBM in Medical Education Message to medical educators from Trisha Greenhalgh, MD, co-author of Evidence Based Health Care Workbook: “An important challenge for medical educators… is to recognize that the competent student (and clinician!) is one who knows how to cope with an immense and rapidly changing body of knowledge and not one who excels in recalling the traditional or memorizing the ephemeral. The deans of medical and nursing schools must develop an infrastructure that allows problem-based, self-directed learning methods to develop within the didactic, lecture- based curricula, which have seen no fundamental changes for two centuries or more.”
ADVANCED EBM: ADVANCED APPLICATIONS APPLY METHODS TO… Care of the individual patient Team protocols Hospital or practice guidelines Continued Learning: problem-based approach Teaching
SELF-DIRECTED LEARNING JAMA Series of User Guides “Clinical Epidemiology: A Basic Science for Clinical Medicine” Week-long workshops On-the-job learning (in your own practice)
EVIDENCE BASED MEDICINEEVIDENCE BASED MEDICINE A new approach to clinical care and researchA new approach to clinical care and research

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Evidence base medicine

  • 1. EVIDENCE BASED MEDICINEEVIDENCE BASED MEDICINE A new approach to clinical care and researchA new approach to clinical care and research
  • 2. PROGRAM OUTLINE 1. Definition of EBM 2. Basic Steps 3. Trials, Studies and Reports 4. Pros, Cons and Limitations 5. EBM in Developing Countries 6. EBM Library 7. Advanced EBM
  • 3. But first, a test…
  • 4. A.A. Training, clinical experience and consultationTraining, clinical experience and consultation with other professionalswith other professionals B.B. Convincing evidence (non-experimental) fromConvincing evidence (non-experimental) from articles, case reports, product literature, etc.articles, case reports, product literature, etc. C.C. Preferences of the patientPreferences of the patient D.D. Active search of Randomized Controlled Trials,Active search of Randomized Controlled Trials, Systematic Reviews, Meta-Analysis ReportsSystematic Reviews, Meta-Analysis Reports WHAT IS THE BASIS OFWHAT IS THE BASIS OF YOURYOUR MEDICAL PRACTICE?MEDICAL PRACTICE? (Check all that apply)
  • 5. A.A. Training, clinical experience and consultationTraining, clinical experience and consultation with other professionalswith other professionals B.B. Convincing evidence (non-experimental) fromConvincing evidence (non-experimental) from articles, case reports, product literature, etc.articles, case reports, product literature, etc. C.C. Preferences of the patientPreferences of the patient D.D. Active search of Randomized Controlled Trials,Active search of Randomized Controlled Trials, Systematic Reviews, Meta-Analysis ReportsSystematic Reviews, Meta-Analysis Reports WHAT IS THE BASIS OFWHAT IS THE BASIS OF YOURYOUR MEDICAL PRACTICE?MEDICAL PRACTICE? EXCELLLENT!EXCELLLENT!
  • 6. BUT… Past knowledge and practice mightBUT… Past knowledge and practice might be outdated or inadequatebe outdated or inadequate
  • 7. A.A. Training, clinical experience and consultation withTraining, clinical experience and consultation with other professionalsother professionals B.B. Convincing evidence (non-experimental) from articles,Convincing evidence (non-experimental) from articles, case reports, product literature, etc.case reports, product literature, etc. C.C. Preferences of the patientPreferences of the patient D.D. Active search of Randomized Controlled Trials,Active search of Randomized Controlled Trials, Systematic Reviews, Meta-Analysis reportsSystematic Reviews, Meta-Analysis reports WHAT IS THE BASIS OFWHAT IS THE BASIS OF YOURYOUR MEDICAL PRACTICE?MEDICAL PRACTICE? FANTASTIC!FANTASTIC!
  • 8. BUT… This evidence may be biased, outdated,BUT… This evidence may be biased, outdated, incorrect, or not applicable to your patientincorrect, or not applicable to your patient ARTICLES ADVERTISEMENTS JOURNALS (1987 to present)
  • 9. A.A. Training, clinical experience and consultation with otherTraining, clinical experience and consultation with other professionalsprofessionals B.B. Convincing evidence (non-experimental) from articles,Convincing evidence (non-experimental) from articles, case reports, product literature, etc.case reports, product literature, etc. C.C. Preferences of the patientPreferences of the patient D.D. Active search of Randomized Controlled Trials,Active search of Randomized Controlled Trials, Systematic Reviews, Meta-Analysis reportsSystematic Reviews, Meta-Analysis reports WHAT IS THE BASIS OFWHAT IS THE BASIS OF YOURYOUR MEDICAL PRACTICE?MEDICAL PRACTICE? WONDERFUL!WONDERFUL! Mutual Respect + Shared Goals = Better Cooperation and Compliance
  • 10. The patient should be involved inThe patient should be involved in all important decisionsall important decisions But this isBut this is NOTNOT always an easy task!always an easy task! And conflictsAnd conflicts WILLWILL occur!occur!
  • 11. But doctor, I DO want to have children! No salt? Lose weight? Forget it! Just give me a pill! I WON’T take that medicine… The side effects are INTOLERABLE! And conflictsAnd conflicts WILLWILL occur!occur!
  • 12. Education about current alternatives and risks is oftenEducation about current alternatives and risks is often needed…needed… for both the Patientfor both the Patient andand the Doctor!the Doctor! But doctor, I DO want to have children! No salt? Lose weight? Forget it! Just give me a pill! I WON’T take that medicine… The side effects are INTOLERABLE!
  • 13. I’ll discuss those risks with my husband. Yes, I’d like to try that new medication! Wow… I never knew that high blood pressure could be so dangerous at my age! Education about current alternatives and risks is oftenEducation about current alternatives and risks is often needed…needed… for both the Patientfor both the Patient andand the Doctor!the Doctor!
  • 14. The patient’s preferences MUST be considered!The patient’s preferences MUST be considered! An important rule in Evidence Based Medicine…An important rule in Evidence Based Medicine… ItIt STARTSSTARTS with the patient andwith the patient and ENDSENDS with the patient.with the patient.
  • 15. A. Training, clinical experience and consultation with other professionals B. Convincing evidence (non-experimental) from articles, case reports, product literature, etc. C. Preferences of the patient D. Active search of Randomized Controlled Trials, Systematic Reviews, Meta-Analysis reports WHAT IS THE BASIS OFWHAT IS THE BASIS OF YOURYOUR MEDICAL PRACTICE?MEDICAL PRACTICE? WOW!!! SUPERB!!!
  • 16. In the practice of Evidence Based Medicine, it isIn the practice of Evidence Based Medicine, it is the physician’sthe physician’s dutyduty to find the best and mostto find the best and most current information and apply it judiciously for thecurrent information and apply it judiciously for the benefit of the patient.benefit of the patient.
  • 17. But… A practice based exclusively on science and math is effective only if your patients are robots or clones! Don’t forget to allow for individual human differences and personal preferences!
  • 18. A. Training, clinical experience and consultation with other professionals B. Convincing evidence (non-experimental) from articles, case reports, product literature, etc. C. Preferences of the patient D. Active search of Randomized Controlled Trials, Systematic Reviews, Meta-Analysis reports WHAT IS THE BASIS OFWHAT IS THE BASIS OF YOURYOUR MEDICAL PRACTICE?MEDICAL PRACTICE? If you checked all 4 items…If you checked all 4 items…
  • 19. A. Training, clinical experience and consultation with other professionals B. Convincing evidence (non-experimental) from articles, case reports, product literature, etc. C. Preferences of the patient D. Active search of Randomized Controlled Trials, Systematic Reviews, Meta-Analysis reports YouYou areare practicingpracticing EVIDENCE BASEDEVIDENCE BASED MEDICINE!MEDICINE! CONGRATULATIONS!
  • 20. EVIDENCE BASED MEDICINEEVIDENCE BASED MEDICINE A new approach to clinical care and researchA new approach to clinical care and research 1. Definition of EBM 2. Basic Steps 3. Trials, Studies and Reports 4. Pros, Cons and Limitations 5. EBM in Developing Countries 6. EBM Library 7. Advanced EBM
  • 21. ““WhatWhat isis Evidence Based Medicine?”Evidence Based Medicine?” ““And where did it come from?”And where did it come from?”
  • 22. A BRIEF HISTORYA BRIEF HISTORY 1980’s: McMasters University in Ontario, Canada1980’s: McMasters University in Ontario, Canada Dr. David Sackett and colleagues proposed EvidenceDr. David Sackett and colleagues proposed Evidence Based Medicine (EBM) as a new way of teaching, learningBased Medicine (EBM) as a new way of teaching, learning and practicing medicine.and practicing medicine. Dr. Sackett defines EBM as:Dr. Sackett defines EBM as: “…“…The conscientious, explicit, and judicious useThe conscientious, explicit, and judicious use of current best evidence in making decisionsof current best evidence in making decisions about the care of individual patients.”about the care of individual patients.”
  • 23. Evidence Based Medicine It is a change in the way physicians practice medicine, teach and learn, and handle research. Clinical practice: Based on the best current evidence (not necessarily on how it’s always been done) Patient Care: Compassionate, patient-oriented (less authoritarian) Learning & Teaching: Problem-based, problem-solving more investigative, less know-it-all-by-yesterday Research: More stringent approach, better proof criteria (more demanding of proof, less room for error)
  • 25. PATIENT Values, Concerns Preferences, Expectations Life predicament PHYSICIAN Training & Experience Current Expertise Continued learning Demand for proof INFORMATION Clinically relevant Proven by research Best up-to-date evidence EBM THE ADDED DETAILS
  • 26. PATIENT Values, Preferences Concerns, Expectations Life predicament PHYSICIAN Training Expertise Continued Learning Demand for proof EBM CHARITY EBM is not a required practice (yet) ENTHUSIASM Challenge, Variety, Change HUMILITY Non-authoritarian practice OPTIONAL COMPONENTS TO BE ADDED BY THE PHYSICIAN INFORMATION Clinically relevant Proven by research Current, up to date
  • 27. “Isn’t this the way we have always practiced medicine?” “Aren’t these just the same old ingredients tossed into a new recipe?” When am I supposed to find the time to do that?
  • 28. The basic steps of EBM
  • 29. THE FIVE BASIC STEPS OF EBM 1. Clinical Question Patient-focused, problem-oriented 2. Find Best Evidence Literary Search 3. Critical Appraisal Evaluate evidence for quality and usefulness 4. Apply the Evidence Implement useful findings in clinical practice 5. Evaluate The information, intervention, and EBM process
  • 30. THE FIVE BASIC STEPS OF EBM 1. Clinical Question Patient-focused, problem-oriented 2. Find Best Evidence Literary Search 3. Critical Appraisal Evaluate evidence for quality and usefulness 4. Apply the Evidence Implement useful findings in clinical practice 5. Evaluate The information, intervention, and EBM process
  • 31. THE FIVE BASIC STEPS OF EBM 1. Clinical Question Patient-focused, problem-oriented 2. Find Best Evidence Literary Search 3. Critical Appraisal Evaluate evidence for quality and usefulness 4. Apply the Evidence Implement useful findings in clinical practice 5. Evaluate The information, intervention, and EBM process
  • 32. THE FIVE BASIC STEPS OF EBM 1. Clinical Question Patient-focused, problem-oriented 2. Find Best Evidence Literary Search 3. Critical Appraisal Evaluate evidence for quality and usefulness 4. Apply the Evidence Implement useful findings in clinical practice 5. Evaluate The information, intervention, and EBM process
  • 33. THE FIVE BASIC STEPS OF EBM 1. Clinical Question Patient-focused, problem-oriented 2. Find Best Evidence Literary Search 3. Critical Appraisal Evaluate evidence for quality and usefulness 4. Apply the Evidence Implement useful findings in clinical practice 5. Evaluate The information, intervention, and EBM process
  • 34. THE FIVE BASIC STEPS OF EBM 1. Clinical Question Patient-focused, problem-oriented 2. Find Best Evidence Literary Search 3. Critical Appraisal Evaluate evidence for quality and usefulness 4. Apply the Evidence Implement useful findings in clinical practice 5. Evaluate The information, intervention, and EBM process
  • 35. The Clinical QuestionThe Clinical Question The FIRST stepThe FIRST step The HARDEST stepThe HARDEST step TheThe MOST IMPORTANTMOST IMPORTANT step!step!
  • 36. FACT: We all have informational needs! That is not a problem!
  • 37. Problems ariseProblems arise • if we fail to recognize those needsif we fail to recognize those needs • if we fail to bridge the information gapif we fail to bridge the information gap • if we fail to ask the right questionsif we fail to ask the right questions
  • 38. And also for othersAnd also for others aroundaround you!you! Lee, exactly how much time did you spend on that big project? Hmmm… Is he about to give me a BONUS? Or is he about to FIRE me? It will make lifeIt will make life easier for you...easier for you... Asking good questionsAsking good questions is ais a skillskill tto be learned.
  • 39. A GOOD QUESTION…A GOOD QUESTION… • Is focused and relevantIs focused and relevant • Provides clearProvides clear communicationcommunication • Clarifies your goal or needClarifies your goal or need • Will reduce the amount ofWill reduce the amount of time needed to obtain thetime needed to obtain the answeranswer Lee, can you give me an accounting of the extra time you spent on that project so that I can charge it back to the client? Oh sure! I’ll have it on your desk by tomorrow!
  • 40. • Be specificBe specific Identify the problem, clarifiy the clinical issue • Be answerableBe answerable through the literature • Contain multiple aspectsContain multiple aspects (patient, options, comparisons, etc) WHEN PRACTICING EBM,WHEN PRACTICING EBM, a good question must also:a good question must also: ACTUAL CASE SCENARIOACTUAL CASE SCENARIO Large cauc male, age 40 2mo ago: Presented with classic nephrotic syndrome, significant symptoms. Bx showed IgAN. Cr 1.4, incr to 2 range, now 1.6 Tried prednisone 60mg qd - tolerated poorly w/tremors and depression. Needs new regimen, but others are aimed more at nephritic IgA rather than nephrotic syndrome. Suggestions? It shouldIt should NOTNOT involve ainvolve a question of Personal Preferencequestion of Personal Preference or Local Concern.or Local Concern.
  • 41. THE EVIDENCE BASED RESPONSETHE EVIDENCE BASED RESPONSE Posted on Nephrol 4/13/03 “In the study below, proteinuria and renal function improved on this combination: Ballardie FW, Roberts IS. Controlled prospective trial of prednisolone and cytotoxics in progressive IgAN. J Am Soc Nephrol 2002 Jan….” “I have patients on this regime who have benefitted.” Regards, Dr. Paulose P. Thomas Nephrologist - Belhoul Apollo Hospital, Dubai, UAE Respondant recommends cyclophosphamide and prednisolone (assuming secondary causes excluded) - a combination that allows for lower dose prednisolone…
  • 42. BACKGROUND and FOREGROUND QUESTIONSBACKGROUND and FOREGROUND QUESTIONS (all part of EBM)(all part of EBM) FOREGROUNDFOREGROUND QUESTIONSQUESTIONS BACKGROUND QUESTIONSBACKGROUND QUESTIONS NEW POSSIBILITIESNEW POSSIBILITIES INDEFINITE ANSWERSINDEFINITE ANSWERS “Where do we want to go, and how else might we get there?” EXPERTGRADSTUDENT “Where are we now? And which way are we headed?” BASIC & CONCRETEBASIC & CONCRETE
  • 43. BACKGROUND QUESTIONSBACKGROUND QUESTIONS BASIC & CONCRETEBASIC & CONCRETE 1. QUESTION • Who, What, Where, When, Why, How 2. VERB • is, causes, does, treats, reduces, cures, prevents, affects 3. GENERAL KNOWLEDGE ABOUT DISORDER clinical manifestations of disease, patient findings, differential diagnosis, etiology, patient experience, comorbid condition, screening and diagnostic tests, prognosis, therapy, risk factors, etc. EXPERTGRADSTUDENT
  • 44. FOREGROUND QUESTIONSFOREGROUND QUESTIONS NEW POSSIBILITIESNEW POSSIBILITIES INDEFINITE ANSWERSINDEFINITE ANSWERS PT AND/OR PROBLEM Differential dx, Unusual presentation, uncertain etiology, pt’s prior experience, comorbid conditions INTERVENTION Exposure, test. Prognostic factor, treatment, pt perception, etc. COMPARISON INTERVENTION OUTCOMES EXPERTGRADSTUDENT
  • 45. EBM QUESTIONEBM QUESTION:: Should include multiple factorsShould include multiple factors (Examples)(Examples) PP PATIENTPATIENT type of patient or population Ex: 47 yr male w/DM2 and cellulitis toe, 25 yr female w/DVT and chest pain EE EXPOSUREEXPOSURE environmental, personal, biological Ex: TB, tobacco, drug, diet, pregnancy or menopause, MRSA, allergy II INTERVENTIONINTERVENTION clinical intervention Ex: medication, procedure, test, surgery, radiation, drug, vaccine CC COMPARISONCOMPARISON compare alternative treatment Ex: other prior, new or existing therapy OO OUTCOMEOUTCOME clinical outcome of interest Ex: Reduced death rate in 5 yrs, decreased infections, fewer hospitalizations
  • 46. FRAMING THE QUESTION (Example: PICO)FRAMING THE QUESTION (Example: PICO) ELEMENTELEMENT PROMPTS THE QUESTIONPROMPTS THE QUESTION:: PatientPatient How would I describe a group of patients similar to mine?How would I describe a group of patients similar to mine? InterventionIntervention What main action am I considering?What main action am I considering? ComparisonComparison What is/are the other options?What is/are the other options? OutcomeOutcome What do I (or the patient) want to happen (or not happen)?What do I (or the patient) want to happen (or not happen)? Example:Example: P:P: In kids under age 12 with poorly controlled asthma on meteredIn kids under age 12 with poorly controlled asthma on metered dose inhaled steroids…dose inhaled steroids… I:I: would the addition of salmetrol to the current therapywould the addition of salmetrol to the current therapy C:C: compared to increasing the dose of current steroidcompared to increasing the dose of current steroid O:O: lead to better control of symptoms without increasing side effects?lead to better control of symptoms without increasing side effects?
  • 47. CATEGORY OF QUESTIONCATEGORY OF QUESTION MAJOR CATEGORIESMAJOR CATEGORIES 1.1. DiagnosisDiagnosis 2.2. PrognosisPrognosis 3.3. Therapy/ TreatmentTherapy/ Treatment PICO 4.4. Harm (iatrogenic, other)Harm (iatrogenic, other) PEO MISCELLANEOUS • Quality of care • Health economics • Office Management • Etc.
  • 48. THE PATIENT’S QUESTIONSTHE PATIENT’S QUESTIONS MustMust be considered!be considered! Often QUALITATIVEOften QUALITATIVE (not based on measureable outcomes) Feelings, ideas, experiences, preferences, concerns, fears, beliefs, ethnicity Usually based on LIMITED BACKGROUNDUsually based on LIMITED BACKGROUND Perception of problem Self-diagnosis Treatment wanted or needed Alternatives (read, heard, considered, tried) What is the patient hoping to avoid? What benefits does the patient want or need most? Etc.
  • 49. QUANTITATIVEQUANTITATIVE: “: “Solid EvidenceSolid Evidence”” • Measurable answer or responseMeasurable answer or response • Necessary for scientific studyNecessary for scientific study • Necessary for the practice of EBMNecessary for the practice of EBM QUALITATIVEQUALITATIVE: “: “Quality of LifeQuality of Life”” • ““Fuzzy” data - Impact on daily life, work, family, etc.Fuzzy” data - Impact on daily life, work, family, etc. • May be very important and influential to decisions –May be very important and influential to decisions – especially for the patientespecially for the patient • Creates added challenge or twist to practice of EBMCreates added challenge or twist to practice of EBM QUANTITATIVE vs QUALITATIVE QUESTIONSQUANTITATIVE vs QUALITATIVE QUESTIONS
  • 50. QUALY: QUALITY ADJUSTED LIFE YEAR 0 2 4 6 8 10 1 2 3 4 5 5-yrTREATMENT COMPARISON Chemo&Rad Radiation only Chemo only 1 2 3 4 5 6 7 8 9 10 2 3 4 5 6 7 8 9 10 PERFECT HEALTH 1 2 3 4 5 6 7 8 9 10 2 3 4 5 6 7 8 9 10 CHRONIC MEDIOCRITY 0 1 2 3 4 5 6 7 8 9 2 3 4 5 6 7 8 9 10 DETERIORATING HEALTH
  • 51. THE FIVE BASIC STEPS OF EBM 1. Clinical Question Patient-focused, problem-oriented 2. Find Best Evidence Literary Search 3. Critical Appraisal Evaluate evidence for quality and usefulness 4. Apply the Evidence Implement useful findings in clinical practice 5. Evaluate The information, intervention, and EBM process
  • 52. Find the Best EvidenceFind the Best Evidence “The Literary Search”“The Literary Search” HINT: If your desk looks like this, it’s probably the LAST place you should start looking!
  • 53. Find the Best EvidenceFind the Best Evidence “The Literary Search”“The Literary Search” The BEST EVIDENCE isThe BEST EVIDENCE is:: ExternalExternal - from outside resources (researchers, experts) CurrentCurrent – not out of date, most recent High QualityHigh Quality - accurate, precise, effective, safe Patient focusedPatient focused - applicable and appropriate for your individual patient
  • 54. FIVE STEPS TO FINDING THE BEST EVIDENCE 1. IDENTIFY NEEDS: What type of information is needed? 2. IDENTIFY RESOURCES: Types, Availability, Timeliness,Costs? 3. SEARCH & RETRIEVE: Use efficient strategies 4. REVIEW : Check quality and usefulness of info 5. INTERPRET: Help patient understand info, application
  • 55. WHAT TYPE OF INFORMATION IS NEEDED?WHAT TYPE OF INFORMATION IS NEEDED? WHAT CATEGORY IS THEWHAT CATEGORY IS THE QUESTION?QUESTION? • DiagnosisDiagnosis • PrognosisPrognosis • TherapyTherapy • HarmHarm
  • 56. WHAT STUDY DESIGN FITS IT BEST?WHAT STUDY DESIGN FITS IT BEST? There are MANY study designs!There are MANY study designs! EXPERIMENTAL TRIALSEXPERIMENTAL TRIALS (Answers questions of diagnosis or treatment) Randomized Controlled Trials (RCTs) Controlled studies Blinded vs Open ETC. OBSERVATIONAL STUDIESOBSERVATIONAL STUDIES Descriptive reports Retrospective studies Cohort studies Case Control ETC.
  • 57. EXAMPLE Randomized Controlled Trials (RCT) “Gold Standard” of research Ideal experimental design - Best design for TREATMENT questions Must identify objective of treatment (Ex: cure, prevent complication, palliation, reassurance) Still not always the right intervention for individual patient at that particular time and place
  • 58. What type of evidence best addresses the question, problem or issue? CLINICAL PRACTICECLINICAL PRACTICE APPROPRIATE DESIGN FOR CLINICAL RESEARCHAPPROPRIATE DESIGN FOR CLINICAL RESEARCH Diagnosis, Dx testing Cross-sectional study – not randomized trial Prognosis Follow-up studies of patients evaluated at same early point of illness Therapy, treatment RCT or Systematic review of multiple RCTs must be used Avoid non-experimental approaches to avoid false conclusions about efficacy Exceptions: When treatment may be successful in an otherwise fatal condition When no studies are available (rare conditions, new treatments, etc.) Harm RCT, Cohort, Case-control OTHER INFORMATIONALOTHER INFORMATIONAL Explore hypothesis Qualitative research History-taking Case control study Individual trial & error n of 1 trial Following clinical course Cohort study Recordkeeping Systematic registry-based (computer supported) research Quality of Care research Individual peer review, Process Evaluation MISCELLANEOUSMISCELLANEOUS Basic Science, Genetics, Immunology, etc.
  • 59. WHAT FORM OF INFORMATION?WHAT FORM OF INFORMATION? Case report Controlled Trial Systematic review Meta-analysis Clinical guidelines etc.
  • 60. LITERARY SEARCH: NEXT STEPLITERARY SEARCH: NEXT STEP IDENTIFY YOUR RESOURCESIDENTIFY YOUR RESOURCES ColleaguesColleagues Consultation, DiscussionConsultation, Discussion (Caution: Response may be an outdated “This is what we(Caution: Response may be an outdated “This is what we do”)do”) Paper resourcesPaper resources books, reports, journalsbooks, reports, journals Electronic databasesElectronic databases Health Literature ServicesHealth Literature Services specialized librarians, staffspecialized librarians, staff Review services, Abstract Services, etc.Review services, Abstract Services, etc.
  • 61. SEARCH AND RETREIVE THE BEST EVIDENCESEARCH AND RETREIVE THE BEST EVIDENCE Learn and Practice various SEARCH STRATEGIESLearn and Practice various SEARCH STRATEGIES:: • To find useful information quicklyTo find useful information quickly • To eliminate irrelevant, inappropriate or weak informationTo eliminate irrelevant, inappropriate or weak information Try to develop the habit of learning as you go;Try to develop the habit of learning as you go; Not just in lengthy formal sessions!Not just in lengthy formal sessions!
  • 62. LITERARY SEARCH STRATEGYLITERARY SEARCH STRATEGY ASK FOR HELP!ASK FOR HELP! SPECIALIZED PERSONNELSPECIALIZED PERSONNEL • track down information, textbooks, articles,track down information, textbooks, articles, guidelinesguidelines • may provide electronic search support or trainingmay provide electronic search support or training EXAMPLESEXAMPLES • Medical Librarians • Medical Informatics Specialists • Specially trained staff member
  • 63. LITERARY RESOURCESLITERARY RESOURCES • TEXTBOOKS (caution – most obsolete!)TEXTBOOKS (caution – most obsolete!) • TraditionalTraditional • Evidence BasedEvidence Based • JOURNALS (may be outdated)JOURNALS (may be outdated) • REVIEW ARTICLES (summaries, abstracts)REVIEW ARTICLES (summaries, abstracts) • SYSTEMATIC REVIEWS (prepared in systematic, rigorousSYSTEMATIC REVIEWS (prepared in systematic, rigorous manner)manner) Ex: Cochrane CollectionEx: Cochrane Collection • META-ANALYSISMETA-ANALYSIS • CLINICAL PRACTICE GUIDELINESCLINICAL PRACTICE GUIDELINES Summarized and easily digestible informationSummarized and easily digestible information
  • 64. ELECTRONIC RESOURCES, DATABASES, INTERNETELECTRONIC RESOURCES, DATABASES, INTERNET Bibliographic DatabaseBibliographic Database Example: Medline, PubMedExample: Medline, PubMed Medical Information Services: Medscape, HDCNMedical Information Services: Medscape, HDCN Review ServicesReview Services SubjectiveSubjective Systematic ReviewsSystematic Reviews Meta-analysisMeta-analysis Examples:Examples: • Cochrane,Cochrane, • Best Evidence,Best Evidence, • Up to DateUp to Date
  • 65. MORE GREAT INTERNET RESOURCESMORE GREAT INTERNET RESOURCES WebsitesWebsites cyberNephrology, National Kidney Foundation. NIDDK,cyberNephrology, National Kidney Foundation. NIDDK, American Heart Association, American Cancer Society.American Heart Association, American Cancer Society. National Institutes of Health, etcNational Institutes of Health, etc Listserve Discussion GroupsListserve Discussion Groups CyberNephrology, C-span, etc.CyberNephrology, C-span, etc. Specialty Electronic DatabasesSpecialty Electronic Databases PsyclitPsyclit CancerLitCancerLit CINAHLCINAHL (allied health and nursing journals)(allied health and nursing journals) EtcEtc
  • 66. OTHER RESOURCESOTHER RESOURCES TapesTapes VideosVideos CD-ROMsCD-ROMs Specialty seminarsSpecialty seminars Product information and comparisonsProduct information and comparisons
  • 67. A closer look at some Internet Resources…
  • 68. MEDLINEMEDLINE WHAT IS IT?WHAT IS IT? Searchable database of medical information compiled by National Library ofSearchable database of medical information compiled by National Library of Medicine in US 1966-presentMedicine in US 1966-present Catalogs articles from approx 4000 world journals (of estimated 12-15k total)Catalogs articles from approx 4000 world journals (of estimated 12-15k total) SEARCH METHODSSEARCH METHODS Any word or words (title, abstract, content, author name, institution, etc.)Any word or words (title, abstract, content, author name, institution, etc.) Medical Subject Heading (MeSH) termsMedical Subject Heading (MeSH) terms A restricted thesaurus of medical titlesA restricted thesaurus of medical titles Articles categorized by most specific possible MeSH headingArticles categorized by most specific possible MeSH heading
  • 69. COST: FREE!COST: FREE! Or may subscribe to companies with specialized search strategies: • Ovid Technologies (ovid) • Silver Platter Information (WinSPIRS) BENEFITSBENEFITS Free Vast database LIMITATIONSLIMITATIONS Not all articles are indexed on Medline (only 1/3 of approx 10 million!) Much material listed and described on Medline can only be accessed through journal article
  • 70. MEDLINE: ELECTRONIC SEARCH STRATEGIES Search through “Clinical Queries” service of PubMed http://www.ncbi.nlm.nih.gov/clinical.html Medical Subject Headings (MeSH) Search filters Search by a text word can supplement a MeSH search Boolean search: “and”, “not”, etc. To increase sensitivity • use “explode” command • avoid using subheadings Online Tutorial is available!Online Tutorial is available!
  • 71. COCHRANE LIBRARY Cochrane Database of Systematic Reviews -systematically compiled reviews of intervention Cochrane Controlled Trials Register -citations of controlled trials identified anywhere in the world Cochrane Review Methodology Database -methodological papers relating to systematic reviews Etc.
  • 72. BEST EVIDENCE Electronic version of two publications: • Evidence Based Medicine • American College of Physicians Journal Club Covers broad topics of information
  • 73. THE FIVE BASIC STEPS OF EBM 1. Clinical Question Patient-focused, problem-oriented 2. Find Best Evidence Literary Search 3. Critical Appraisal Evaluate evidence for quality and usefulness 4. Apply the Evidence Implement useful findings in clinical practice 5. Evaluate The information, intervention, and EBM process
  • 74. CRITICAL APPRAISALCRITICAL APPRAISAL Interpreting the evidenceInterpreting the evidence • How to read a paperHow to read a paper • How to do the mathHow to do the math
  • 75. CRITICAL APPRAISALCRITICAL APPRAISAL IMPORTANT!IMPORTANT! You doYou do NOTNOT have to become a researcher,have to become a researcher, epidemiologist, or statistician to practice EBM.epidemiologist, or statistician to practice EBM. Focus on how toFocus on how to USEUSE research reports –research reports – not on how to generate them!not on how to generate them!
  • 76. HOWEVER…HOWEVER… You must have a solid understanding ofYou must have a solid understanding of basic research principlesbasic research principles andand study designsstudy designs in order to understandin order to understand and interpret the evidence!and interpret the evidence! CRITICAL APPRAISALCRITICAL APPRAISAL
  • 77. TYPES OF STUDIES AND REPORTS Randomized Controlled Trial - “The Gold Standard” Systematic review Meta-analysis Retroactive vs Prospective Incidence Prevalence Case Control Cohort (Follow-up) Cross-sectional Ecologic Longitudinal Experimental Blinded vs Open Qualitative Screening
  • 80. THETHE TIMETIME FACTORFACTOR When was the study done?When was the study done? In what time direction is it headed?In what time direction is it headed? What was its duration?What was its duration? RETROSPECTIVE PROSPECTIVEPROSPECTIVE
  • 81. THETHE TIMETIME FACTORFACTOR When was the study done?When was the study done? What year?What year? What technology? (ie: test, drug, equipment, procedure)What technology? (ie: test, drug, equipment, procedure) Any associated social factor or historical event?Any associated social factor or historical event?
  • 82. THETHE TIMETIME FACTORFACTOR What was the Study Duration?What was the Study Duration? Was it an appropriate length of time for the intended goal? Limited time study or ongoing? Was study completed? Stopped early?
  • 83. ““LOOKING BACKLOOKING BACK”” Historical Review orHistorical Review or InvestigationInvestigation ““LOOKING FORWARDLOOKING FORWARD”” Future ResultsFuture Results The Great UnknownThe Great Unknown PRESENTPAST FUTURE In what direction is it headed?In what direction is it headed? RETROSPECTIVE PROSPECTIVEPROSPECTIVE
  • 84. PROPRO •May provide goodMay provide good direction for future studydirection for future study ““Hind Sight is 20/20”Hind Sight is 20/20” CON:CON: •Prone to BiasProne to Bias •A“Fishing Expedition” forA“Fishing Expedition” for positive resultspositive results PROPRO •Lower risk of biasLower risk of bias CON:CON: May get faulty results basedMay get faulty results based on incomplete data oron incomplete data or insignificant subgroupsinsignificant subgroups (Example of Error: Untreated(Example of Error: Untreated hypertension unlikely to causehypertension unlikely to cause cardiac event in child, so treatmentcardiac event in child, so treatment is unnecessary below age 18yrs)is unnecessary below age 18yrs)PRESENT In what direction is it headed?In what direction is it headed? RETROSPECTIVE PROSPECTIVEPROSPECTIVE
  • 85. “Was there a similar comparison group?”
  • 86. Experimental Intervention No comparison group All subjects receive Experimental Intervention
  • 87. Experimental Intervention NO EVENT OUTCOME EVENT ““Trial and Error?Trial and Error?”” or ““Before & After?Before & After?”” UNCONTROLLED STUDIES
  • 88. PROBLEMS POSITIVE OUTCOME MAY BE DUE TO: •Other factors •Natural course of disease (some get better, some don’t!) •Spontaneous change of health •Placebo Effect •Hawthorne Effect NEGATIVE OUTCOME May be due to study treatment. Could be disastrous! BENEFITS Can answer some questions about: •likelihood of response •adverse effect, etc. VERY PATIENT-SPECIFIC! MAY BE ONLY OPTION Rare conditions Previously unknown conditions ““Trial and ErrorTrial and Error”” ““Before & AfterBefore & After”” UNCONTROLLED STUDIES Generally NOT accepted: Potentially Dangerous and Flawed Prone to BIAS! “Traditional Study Method” May produce strong results
  • 89. SMALLPOX VACCINATION SMALLPOX VACCINE 1. 1796: Edward Jenner inoculates 8yr-old James Phipps with cowpox virus from a milkmaid’s hands. Child develops illness, recovers. 2. Two weeks later, inoculates same child with smallpox virus. Child survives, no illness. (Centuries later, smallpox eradicated!) n=1 GOOD! Resistant to Cowpox and Smallpox (NO DISEASE OUTCOME) James Phipps, age 8 years Example#1Example#1 UNCONTROLLED TRIALS: “TRIAL AND ERROR”
  • 90. Drinks culture of H.pylori HELICOBACTER PYLORI - GASTRIC ULCERS 1982: Australian microbiologist Barry J. Marshall presents evidence showing a possible infectious cause for gastric ulcers. Suggests they may be treatable with antibiotics. Findings are met with disinterest and disbelief by medical community. Lacks support for further study. 5 years later: Prepares a broth of live organisms isolated from a gastric ulcer patient and drinks it. Becomes violently ill, develops severe acute gastritis. 1990’s Antibiotics are used routinely to cure some gastric ulcers! Example #2Example #2 NO OUTCOME SEVERE GASTRITIS n=1UNCONTROLLED TRIALS: “TRIAL AND ERROR” Dr. Marshall Microbiologist
  • 91. UNCONTROLLED TRIAL Experimental Intervention Present FUTURE May represent the ONLY treatment option for a new or rare disease DIED RECOVERED
  • 93. Nothing Placebo Observation only ExperimentalI ntervention Control group may receive… Only the TEST group receives the Experimental Intervention CONTROLLED STUDY Other IMPORTANT All other differences should be minimized or eliminated to reduce potential BIAS Gold Standard Treatment
  • 94. Experimental Intervention Control Group RANDOMIZEDRANDOMIZED CONTROLLEDCONTROLLED TRIAL (RCT)TRIAL (RCT) ““The GoldThe Gold Standard”Standard”
  • 95. 1944 TUBERCULOSIS TREATMENT: Streptomycin vs Bedrest1944 TUBERCULOSIS TREATMENT: Streptomycin vs Bedrest Streptomycin (n=50) Bedrest (n=50) THE FIRST RANDOMIZED CONTROLLED TRIAL By Sir Austin Bradford Hill (BLINDED)
  • 96. Experimental Intervention Control Group OPEN vs BLINDED STUDIESOPEN vs BLINDED STUDIES OPENOPEN
  • 98. BLINDING SINGLE BLINDED: Pt unaware of what group s/he is in DOUBLE BLINDED: Pt and MD unaware OPEN LABEL: Everyone is aware
  • 99. RANDOMIZED vs NON-RANDOMIZED TRIALSRANDOMIZED vs NON-RANDOMIZED TRIALS Experimental Intervention Control Group How is this group divided?
  • 100. NON-RANDOMIZEDNON-RANDOMIZED Experimental Intervention Control Group Assigned toAssigned to groups, usuallygroups, usually by theby the researcherresearcher Potential for RESEARCHER BIAS!Potential for RESEARCHER BIAS!
  • 101. RANDOMIZEDRANDOMIZED Experimental Intervention Control Group Random method ofRandom method of assignment usedassignment used Maximizes “sameness,” Eliminates BIAS!Maximizes “sameness,” Eliminates BIAS!
  • 102. RANDOMIZEDRANDOMIZED CONTROLLED TRIAL (RCT)CONTROLLED TRIAL (RCT) (EXPERIMENTAL TRIAL)(EXPERIMENTAL TRIAL) Experimental Intervention Control Group Present FUTURE ““The Gold Standard”The Gold Standard”
  • 103.
  • 104. Experimental Intervention Trial of Medicine 1 Or placebo TRIAL SERIES FOR INDIVIDUAL PATIENT n=1One patient, series of tests Experimental Intervention Trial of Medicine 2 Or placebo GOOD GOOD NO CHANGE OR BAD NO CHANGE OR BAD
  • 105. Why a TRIAL SERIES for one patient? EXAMPLES: Trial of different medications and/or placebo for child reported to have ADHD symptoms that are not clinically apparent Trial of different analgesics for patient with chronic pain from a combination of diseases not previously studied PATIENT •Must be blinded •Must keep diary or complete questionnaire PHYSICIAN •May need to be blinded (enlist help of pharmacist!) •Must treat patient as usual in all other respects BENEFIT Produces data most applicable to the individual patient
  • 106. Intervention A ONE GROUP, MULTIPLE TESTS CROSSOVER TRIALS Intervention B Intervention B Intervention A ASSESS OUTCOMES #1 ASSESS OUTCOMES #2 COMPARE OUTCOMES (Best if participants are blinded)
  • 107. Intervention A CROSSOVER TRIALS Intervention B Intervention B Intervention A ASSESS OUTCOMES #1 ASSESS OUTCOMES #2 Fewer participants needed than a RCT! Lower costsAll are in experimental group PROS & CONSPROS & CONS
  • 108. Intervention A CROSSOVER TRIALS Intervention B Intervention B Intervention A ASSESS OUTCOMES #1 ASSESS OUTCOMES #2 MUST HAVE SHORT CARRYOVER EFFECTMUST HAVE SHORT CARRYOVER EFFECT MUST HAVE SHORT WASHOUT EFFECTMUST HAVE SHORT WASHOUT EFFECT (OR WAIT A SUITABLY LONG WASHOUT TIME!)(OR WAIT A SUITABLY LONG WASHOUT TIME!) PROS & CONSPROS & CONS
  • 110. CASE CONTROL Present NEVER SMOKED (PAST) (“A LOOK BACK”) SMOKER LUNG CANCER HEALTHY RISK FACTOR
  • 111. CASE CONTROL Present NORMAL WEIGHT (“A LOOK BACK”) OBESITY DM TYPE II NON-DIABETIC RISK FACTOR
  • 112. COHORT IS RISK FACTOR PRESENT? Future Outcome “FOLLOWUP DESIGN” (Exclude those with outcome already!)
  • 113. COHORT IS RISK FACTOR PRESENT? Future Outcome “FOLLOWUP DESIGN” Present TO INVESTIGATE ETIOLOGY OR HYPOTHETICAL CAUSE OF DISEASE/OUTCOME
  • 114. COHORT Present RISK FACTOR Hgb <9 EXAMPLE DIALYSIS PATIENTS Measures future outcome for dialysis pts w/o treatment of anemia
  • 115. CROSS SECTIONAL DESIGN ? Cause ? Risk factors A look back
  • 116. CROSS SECTIONAL DESIGN INFANT DEATHSSIDS DEATHS OTHER CAUSES RISK = SLEEP PRONE
  • 117. NO CONTROL OVER CONTROL GROUP VARIATION IN TREATMENT OR METHOD NON-SIMILAR CONDITIONS Social Personal Comorbid conditions Other treatments Etc. Not usually accepted by medical journals (accepted in popular press, not reviewed) CURRENT GROUP OF PATIENTS Problems of looking back
  • 118. RANDOMIZED & CONTROLLED TRIAL (RCT)RANDOMIZED & CONTROLLED TRIAL (RCT) Experimental Intervention Control Group PROSPECTIVEPROSPECTIVE MAY BEMAY BE BLINDEDBLINDED
  • 119. START WITH YOUR TARGET POPULATION
  • 120. START WITH YOUR TARGET POPULATION Set CRITERIA forSet CRITERIA for INCLUSION / EXCLUSIONINCLUSION / EXCLUSION This will determine:This will determine: ELIGIBILITYELIGIBILITY at the startat the start VALIDITYVALIDITY at the endat the end
  • 121. START WITH YOUR TARGET POPULATION
  • 122. ELIMINATE THOSE WHO DO NOT MEET THE CRITERIAELIMINATE THOSE WHO DO NOT MEET THE CRITERIA
  • 123. NEXT: GATHER A SAMPLE GROUP
  • 124. THE SAMPLE GROUP WILLTHE SAMPLE GROUP WILL:: •Represent the target populationRepresent the target population •Meet the criteria for inclusion / exclusionMeet the criteria for inclusion / exclusion SIDE NOTES…SIDE NOTES… Study should be approved by anStudy should be approved by an Ethics CommitteeEthics Committee Informed consent should beInformed consent should be obtained from study participantsobtained from study participants
  • 125. SAMPLE GROUPSAMPLE GROUP MAYMAY BE SUBDIVIDED FURTHERBE SUBDIVIDED FURTHER STRATIFICATIONSTRATIFICATION Divide into subgroups based onDivide into subgroups based on important similar characteristicsimportant similar characteristics RANDOMIZATIONRANDOMIZATION Divide into sub-groups based onDivide into sub-groups based on unknown confoundersunknown confounders
  • 126. STRATIFICATIONSTRATIFICATION ““important similar characteristics”important similar characteristics” Examples: • Male or Female • Age • Stage of illness • Prior illness or treatment • Hospital vs Office groups • Comorbid condition • Etc.
  • 128. RANDOMIZATIONRANDOMIZATION ““unknown confounders”unknown confounders” Examples:Examples: • Postal codePostal code • Month of birthMonth of birth • Random numberRandom number • Etc.Etc.
  • 129. EXAMPLE OF RANDOMIZATIONRANDOMIZATION DX IN JANUARY-JUNE DX IN JULY-DECEMBER
  • 130. Experimental Intervention Control Group Next… Divide your sample group(s) intoDivide your sample group(s) into STUDY GROUPSSTUDY GROUPS ““Test Group”Test Group” ““Baseline Group”Baseline Group”
  • 131. Experimental Intervention Control Group Next… Divide your sample group(s) intoDivide your sample group(s) into STUDY GROUPSSTUDY GROUPS Receives ExperimentalReceives Experimental InterventionIntervention ““Baseline GroupBaseline Group”” • NothingNothing • ObservationObservation • ““Same” miscellaneousSame” miscellaneous intervention (non-intervention (non- experimental)experimental) • PlaceboPlacebo • ““Gold Standard” therapy -Gold Standard” therapy - especially if unethical to doespecially if unethical to do otherwise!otherwise! ““Test GroupTest Group””
  • 132. ASSIGN PATIENTS TO STUDY GROUPS Experimental Intervention Control Group Use caution against bias! Sample Group Study Groups
  • 133. Experimental Intervention Control Group STUDY INVESTIGATOR  usually assigns patients to study groups.  usually has a personal preference for the treatment or patient  might unconsciously “work harder” to make the study work with non-preferred candidates = POTENTIAL FOR BIAS
  • 134. Experimental Intervention Control Group Use random separation and assignment! RANDOMIZED CONTROLLED TRIAL (RCT)RANDOMIZED CONTROLLED TRIAL (RCT)
  • 136. RANDOMIZED CONTROLLED TRIAL (RCT)RANDOMIZED CONTROLLED TRIAL (RCT) Experimental Intervention Control Group FUTUREFUTURE PresentProceed with study
  • 137. Experimental Intervention Control Group RANDOMIZED CONTROLLED TRIAL (RCT)RANDOMIZED CONTROLLED TRIAL (RCT) EXPERIMENTAL EVENT RATE (EER) CONTROL EVENT RATE (CER)
  • 138. Experimental Intervention Control Group FUTURE Present RANDOMIZED CONTROLLED TRIAL (RCT)RANDOMIZED CONTROLLED TRIAL (RCT) EXPERIMENTAL EVENT RATE (EER) CONTROL EVENT RATE (CER) ““The GoldThe Gold Standard”Standard”
  • 139. Disadvantages of RCT Expensive large # pts needed Prolonged recruitment and follow-up time needed Funding difficult to obtain except w/support of pharmaceutical companies (problematic!)
  • 141. THE FIVE BASIC STEPS OF EBM 1. Clinical Question Patient-focused, problem-oriented 2. Find Best Evidence Literary Search 3. Critical Appraisal Evaluate evidence for quality and usefulness 4. Apply the Evidence Implement useful findings in clinical practice 5. Evaluate The information, intervention, and EBM process
  • 142. Interpreting the evidenceInterpreting the evidence • How to read a paperHow to read a paper • How to do the mathHow to do the math CRITICAL APPRAISALCRITICAL APPRAISAL
  • 143. EVALUATE WRITTEN EVIDENCE FOR… Quality Usefulness …BY ASSESSING Validity Reliability Relevance Clinical importance
  • 144. Critical Appraisal: VALIDITYCritical Appraisal: VALIDITY What was the original purpose of the studyWhat was the original purpose of the study?? When was it preparedWhen was it prepared?? By whomBy whom?? • credentials?credentials? • affiliations?affiliations? Sample populationSample population Did the subjects represent an appropriate test group? How were they selected? Were controls used? Were groups similar for important prognostic characteristics?
  • 145. VALIDITYVALIDITY How was the information gathered and processed?How was the information gathered and processed? Were groups treated equally except for trial therapy? Were appropriate criteria used to measure results? Were criteria applied rigorously? Was the study completed?Was the study completed? (Or ended early for a specified reason?) Did the study account for all test subjectsDid the study account for all test subjects?? Including subjects lost to follow-up? Were ALL pts analyzed in their allocated groups? (ie: INTENTION TO TREAT - not “completed treatment” analysis)
  • 146. VALIDITYVALIDITY InformationInformation Does the paper support its claims? Is the information accurately presented? Does it represent the truth? ResultsResults Are the results believable? To what degree of confidence? Ex: Disagreement is not uncommon on angiograms, EKGs, radiographs, pathology, PAP tests, etc.
  • 147. VALIDITYVALIDITY ComprehensivenessComprehensiveness Size: Was it large enough to yield credible results? Thoroughness: Was it complete enough? Duration: Was it long enough?
  • 148. CRITICAL APPRAISAL:CRITICAL APPRAISAL: RELIABILITY Do we trust the information and results? 1. APPROPRIATE TYPE OF STUDY 2. REPRODUCEABILITY 3. INTERPRETATION OF RESULTS 4. BIAS
  • 149. RELIABILITY APPROPRIATE TYPE OF STUDY Was the type of study design used proper for the question?Was the type of study design used proper for the question? Example: RCT would be choice for questions on TREATMENT
  • 150. RELIABILITY Are the Measurements and Results reproducibile? Different determinations may be caused by: • Variation in measurement methods • Different interpretation of results • Lack of agreement Example: BP checks on same patient may vary. Are differences result of pt factor, examiner factor, treatment factor, normal variance Would the same results be obtained if patient is re-measured? (with identical procedure) • at another time? • by another person? Were any similar studies done? • Was the information comparable? • Did the results agree?
  • 151. RELIABILITY INTERPRETATION OF RESULTS Is there consistency among researchers?Is there consistency among researchers? Different determinations may be caused by: • Variation in measurement methods • Different interpretation of results • Lack of agreement EXAMPLE: BANFF CONFERENCE - Setting standards in Transplant Pathology established by Kim Solez, MD Were any new questions or controversies raised by the study?Were any new questions or controversies raised by the study?
  • 152. RELIABILITYRELIABILITY IS THERE ANY EVIDENCE OF BIASIS THERE ANY EVIDENCE OF BIAS?? A dangerous pitfall!A dangerous pitfall! • PATIENTSPATIENTS • RESEARCHERSRESEARCHERS
  • 153. PATIENT BIASPATIENT BIAS Social Desirability BiasSocial Desirability Bias Patient responds in the wayPatient responds in the way they perceive as correctthey perceive as correct • to support MDto support MD • to support a preconceivedto support a preconceived notion (ie: foods vs ADD)notion (ie: foods vs ADD) Patient denies unhealthyPatient denies unhealthy behavior, gets misclassifiedbehavior, gets misclassified Ex: Smoker vs Non-smokerEx: Smoker vs Non-smoker
  • 154. PATIENT BIASPATIENT BIAS Hawthorne EffectHawthorne Effect AuthorsAuthors mustmust take steps totake steps to reduce this bias by treatingreduce this bias by treating all equally!all equally! Ex: Weigh all patients with sameEx: Weigh all patients with same frequency, even for group not onfrequency, even for group not on special dietspecial diet People act differently whenPeople act differently when they know they are beingthey know they are being watched.watched. Ex: Follow more careful dietEx: Follow more careful diet when regular weigh-ins arewhen regular weigh-ins are scheduledscheduled
  • 155. RESEARCHER BIAS Who sponsored or funded the study? Personal gain or loss from results? Affiliates Special interests Conflict of interest Biased goal? To satisfy editors and reviewers… rather than solve real life clinical problems
  • 156. Criteria bias? Risk-avoidance by researchers (will focus energy on topics that produce positive results) Bias toward patients? Sample selection criteria used (inclusive, exclusive) Assignment to test group or control - Random? Blind? RESEARCHER BIAS
  • 157. Data collection methods used • applied similarly to all subjects, including controls? • starting point – prospective/retrospective, stage of patient? • Was assessment blind? Data analysis • Were all potential subjects included in denominator or otherwise accounted? • Were they evaluated in originally designated group? (INTENTION TO TREAT) RESEARCHER BIAS
  • 158. REDUCING OR ELIMINATING BIAS AND ERROR CONDUCT BLIND STUDIES • Single • Double-blinded USE INDEPENDENT OBSERVERS • When doctor and/or patient can not be blinded, blinded IO measures outcome • IO may even be unaware of study hypothesis USE MULTIPLE OBSERVERS Ex: Send subject slides to multiple pathologists for interpretation ESTABLISH CLEAR STANDARDS • Exact methods to use to reduce variation in technique among researchers • Clear wording on surveys, etc VALIDATING INSTRUMENTS • Repeat screening to check for correct answers on surveys • More frequent evaluations or surveys prevent guesstimates common to less frequent evaluation
  • 159. NEXT STEP IN CRITICAL APPRAISAL:NEXT STEP IN CRITICAL APPRAISAL: RELEVANCERELEVANCE QUESTION: Is the report applicable to our…QUESTION: Is the report applicable to our… Problem?Problem? ““Does it address the questions raised?”Does it address the questions raised?” Patient(s)?Patient(s)? ““Will my patient respond like those in the study?”Will my patient respond like those in the study?” Practice?Practice? ““Can it be done within my practice or circle?”Can it be done within my practice or circle?”
  • 160. ARE THE STUDY PATIENTS • Comparable within the study? (similar traits, age, socioeconomic group, stage of illness, treatment, etc.) • Comparable to your patient? ARE THE STUDY PROFESSIONALS • Comparable to you? (general/specialist, primary care/teaching hospital, etc.)
  • 161. NEXT STEP in CRITICAL APPRAISALNEXT STEP in CRITICAL APPRAISAL CLINICAL IMPORTANCECLINICAL IMPORTANCE Information can be true and interesting in theory,Information can be true and interesting in theory, yetyet uselessuseless in clinical practice!in clinical practice! 1.1. Is the information clinically important?Is the information clinically important? 2.2. If yes, how important is it?If yes, how important is it? • study design - See: Hierarchy of Evidencestudy design - See: Hierarchy of Evidence • weight of resultsweight of results
  • 162. HEIERARCHY OF EVIDENCEHEIERARCHY OF EVIDENCE (value of study design to maximize wt, minimize bias)(value of study design to maximize wt, minimize bias) 1. Systematic Review of all relevant RCTs 2. At least one properly designed RCT 3. Trials and case studies 4. Well-designed Controlled Trial without Randomization 5. Well designed Cohort or Case Control Studies, preferably from >1 centre or group 6. Multiple Time series with or without intervention 7. (Exception: Dramatic results in uncontrolled trials, such as introduction of PCN in the 1940s) 8. Opinions of respected authorities, based on 9. Clinical expertise 10. Descriptive studies 11. Reports of Expert Committees
  • 163. RANDOMIZEDRANDOMIZED CONTROLLED TRIAL (RCT)CONTROLLED TRIAL (RCT) Evaluation of RCT Were all clinically appropriate outcomes measured? Did an ethics committee approve the study? Any statistically significant results also clinically significant? Any significant adverse reactions? Was follow-up procedural analysis identical? Was continuous data analysis vs end of trial data used?
  • 164. Interpreting the evidenceInterpreting the evidence • How to read a paperHow to read a paper • How to do the mathHow to do the math
  • 165. HOW TO DO THE MATH Incidence Prevalence Statistical Formulas +/- Predictive Values - Probability - The p value Relative Risk Risk Reduction Odds Ratios NNT (Number Needed to Treat) – Risk Reduction Confidence Intervals Sensitivity and Specificity Regression Analysis Subgroup Analysis Health Status Evaluation Health Economics
  • 166. ACCOUNT FOR ALL even if •Non-compliant •Lost to follow-up Analyze as a member of the originally assigned group! Analysis SHOULD BE BASED ON • INTENTION TO TREAT • NOT on “completed treatment” analysis OUTCOMES: NOT “STUDY FAILURES” OUTCOMES RELATE TO EVERYDAY CLINICAL PRACTICE, including… • Deaths • Poor compliance • Wrong treatment received • Lost to follow-up • Etc.
  • 167. INCIDENCE & PREVALENCE NEPHROL, a service of NKF cyberNephrology 7/10/03 10:17:12AM Dear Nephrolers, I would like to know how to calculate incidence and prevalence of B and C virus in HD. Thank you in advance. Mario Cuba, MD Servicio de Nefrologia Hospital Lucia Iniguez Landin Holguin, Cuba
  • 168. INCIDENCE & PREVALENCE Response from Michel Jadoul, MD NEPHROL, a service of NKF cyberNephrology Prevalence: total number of positive patients divided by total number of patients: 20+/200=10% Incidence: number of new positive cases/total number of cases negative at start of period (e.g; year)/period (year?) thus : for instance 2 new positive cases /100 negative cases at start of year=2%/year. M.Jadoul, M.D.
  • 169. PREVALENCE BB BB BB BB BB BB BB BB BB BB 10 cases Hep B in 100 patients 10 / 100 = 0.10 PREVALENCE = 10%
  • 170. INCIDENCE BB BB BB BB BB BB BB BB BB BB BB BB BB BBBB 1 year period 90 HBsA(-) at start of study 5 new cases 5 / 90 = 0.06 INCIDENCE = 6% per year
  • 171. BB BB BB BB BB BB BB BB BB BB BB BB BB BBBB RECALCULATED PREVALENCE 16 cases Hep B in 100 patients 16 / 100 = 0.16 NEW PREVALENCE = 16%NEW PREVALENCE = 16%
  • 172. COMPARISON STUDIES: NEW DIAGNOSTIC TESTS RESULTS OF GOLD STANDARD TEST EXPERIMENTALTEST POSITIVE NEGATIVE DISEASE PRESENT NO DISEASE TRUE (+) a FALSE (+) b FALSE (-) c TRUE (-) d COMPARING A NEW TEST AGAINST THE GOLD STANDARD TEST
  • 173. ACCURACY OF TEST - COMPARE TO GOLD STANDARD What is the usefulness of the test in various groups and subgroups of pts? RESULTS OF GOLD STANDARD TEST EXPERIMENTALTEST TEST POSITIVE a + b TEST NEGATIVE c + d DISEASE PRESENT a + c NO DISEASE PRESENT b + d TRUE (+) a FALSE (+) b FALSE (-) c TRUE (-) d TESTS ARE RARELY 100% ACCURATE THEY MUST BE COMPARED AGAINST THE GOLD STANDARD
  • 174. ACCURACY OF TEST - COMPARE TO GOLD STANDARD What is the usefulness of the test in various groups and subgroups of pts? RESULTS OF GOLD STANDARD TEST EXPERIMENTAL TEST TEST POSITIVE TEST NEGATIVE DISEASE PRESENT DISEASE NOT PRESENT TRUE (+) a FALSE (+) b FALSE (-) c TRUE (-) d TESTS ARE RARELY 100% ACCURATE THEY MUST BE COMPARED AGAINST THE GOLD STANDARD TOTALS c + d a + b TOTALS a+b+c+db + da + c
  • 175. ACCURACY OF TEST - COMPARE TO GOLD STANDARD What is the usefulness of the test in various groups and subgroups of pts? RESULTS OF GOLD STANDARD TEST EXPERIMENTAL TEST TEST POSITIVE TEST NEGATIVE DISEASE PRESENT DISEASE NOT PRESENT TRUE (+) a FALSE (+) b FALSE (-) c TRUE (-) d TESTS ARE RARELY 100% ACCURATE THEY MUST BE COMPARED AGAINST THE GOLD STANDARD TOTALS c + d a + b TOTALS a+b+c+db + da + c SENSITIVITY SPECIFICITY
  • 176. SENSITIVITY AND SPECIFICITY SENSITIVITY = PATIENT (+) TEST (+) Probability that patient WITH disease will have ABNORMAL result (instead of False Negative) SPECIFICITY = PATIENT (-) TEST (-) Probability that patient WITHOUT disease will have NORMAL result (instead of False Positive) OVERALL DISCRIMINATION OF TESTS High SENSITIVITY = low number false negatives High SPECIFICITY = low number of false positives Best accuracy if both factors are close to 100%
  • 177. SENSITIVITY = a / (a + c) PATIENT (+) TEST (+) SPECIFICITY = d / (b + d) PATIENT (-) TEST (-) POSITIVE PREDICTIVE VALUE = a / (a + b) If pt tests (+), what is the likelihood s/he has the disease? NEGATIVE PREDICTIVE VALUE = d / (c + d) If pt tests (-), what is the likelihood s/he does NOT have the disease? PREVALENCE = (a + c) / (a + b + c + d) ACCURACY = (a + d) / (a + b + c + d) Proportion of results that correctly identify pts with and without disease (True + and True - as proportion of all results) LIKELIHOOD RATIO = sensitivity / (1 - specificity) How likely is it that + result accurately indicates disease, and - result no disease?
  • 178. LIKELIHOOD RATIO (LR) Because Sensitivity and Specificity are NOT always 100% How likely is it that + result accurately indicates disease, and - result no disease? LIKELIHOOD RATIO FOR A POSITIVE RESULT (LR+) Probability of (+) result in diseased subject divided by Probability of (+) result in a healthy subject - or worded differently - Sensitivity divided by 100% - Specificity LIKELIHOOD RATIO FOR A NEGATIVE RESULT (LR-) 100% - Sensitivity divided by Specificity DISCRIMINATION = ZERO IF LR = 1
  • 179. EVALUATING STUDY RESULTSEVALUATING STUDY RESULTS Example: Mortality rates in 4444 pts x 5.4 trial years: 11.5% Placebo 8.2% Medicine RRR 29% (Relative Risk Reduction) ARR 3.3% (Absolute Risk Reduction) NNT 30 (Number needed to treat for 5.4 years to save 1 life
  • 180. QALY = QUALITY ADJUSTED LIFE YEARQALY = QUALITY ADJUSTED LIFE YEAR QUALITY RATING NOT specific for disease or treatment! Value rating - subject to different values of patients, physician, community • Patient-based • Economy-based - cost-utility/cost-effectiveness analysis Compares outcomes of conditions or intervention(s) • State of health - vs -Time spent in it
  • 181. QUALY: QUALITY ADJUSTED LIFE YEAR 0 2 4 6 8 10 1 2 3 4 5 5-yrTREATMENT COMPARISON Chemo&Rad Radiation only Chemo only 1 2 3 4 5 6 7 8 9 10 2 3 4 5 6 7 8 9 10 PERFECT HEALTH 1 2 3 4 5 6 7 8 9 10 2 3 4 5 6 7 8 9 10 CHRONIC MEDIOCRITY 0 1 2 3 4 5 6 7 8 9 2 3 4 5 6 7 8 9 10 DETERIORATING HEALTH
  • 182. TEST RESULTS: VARIABILITY FACTFACT: Study results may vary.: Study results may vary. Group too small Not representative of larger group Etc. Age, sex, race, condition, culture, etc. Compliancy issues (patient and physician!) May be discovered or identified through study
  • 183. TEST RESULTS: VARIABILITY FACTFACT:: Variability may or may not be significantVariability may or may not be significant Group too small Not representative of larger group Etc. Age, sex, race, condition, culture, etc. Compliancy issues (patient and physician!) May be discovered or identified through study
  • 184. TEST RESULTS: VARIABILITY Group too small Not representative of larger group Etc. Age, sex, race, condition, culture, etc. Compliancy issues (patient and physician!) May be discovered or identified through study Obviously faulty studies should be eliminated.Obviously faulty studies should be eliminated.
  • 185. TEST RESULTS: VARIABILITY Group too small Not representative of larger group Etc. Age, sex, race, condition, culture, etc. Compliancy issues (patient and physician!) May be discovered or identified through study Some variability should be expected in the rest.Some variability should be expected in the rest.
  • 186. TEST RESULTS: VARIABILITY Group too small Not representative of larger group Etc. Age, sex, race, condition, culture, etc. Compliancy issues (patient and physician!) May be discovered or identified through study Some factors are completely unexpected.Some factors are completely unexpected.
  • 187. and variability due toand variability due to The statistics allow us to distinguish betweenThe statistics allow us to distinguish between
  • 188. PROBABILITYPROBABILITY CHANCECHANCE WARNING PROBABILITY should NOT be confused with CHANCE! Statistically significant Results are measurable and predictable Affected by sample size (1 in 20 is less convincing than 1 in 10,000) No statistical significance Random, unpredictable
  • 189. A Study in Probability… QUESTION #1QUESTION #1:: What percentage of patients will develop diarrhea whileWhat percentage of patients will develop diarrhea while taking Antibiotic A?taking Antibiotic A? QUESTION #2QUESTION #2:: Will the results be the same, better or worse onWill the results be the same, better or worse on Antibiotic B?Antibiotic B? PROBABILITYPROBABILITY
  • 190. 50 50 50 50 50 50 50 50 50 50 5050 50 5050 50 50 50 50 50 20 study groups 50 pts each study 1000 patients total QUESTION #1QUESTION #1:: What percentage of patients will develop diarrhea whileWhat percentage of patients will develop diarrhea while taking Antibiotic A?taking Antibiotic A?
  • 191. 4 6 108 12 14 16% Conduct studies Organize results NUMBEROFSTUDIES PERCENTAGE OF PATIENTS WITH DIARRHEA QUESTION #1QUESTION #1:: What percentage of patients will develop diarrhea whileWhat percentage of patients will develop diarrhea while taking Antibiotic A?taking Antibiotic A?
  • 192. 4 6 108 12 14 16% NUMBEROFSTUDIES PERCENTAGE OF PATIENTS WITH DIARRHEA IDENTIFY STATISTICALLY SIGNIFICANT RESULTS The Bell CurveThe Bell Curve
  • 193. Most COMMONCOMMON result = 4 6 108 12 14 16% MODEMODENUMBEROFSTUDIES PERCENTAGE OF PATIENTS WITH DIARRHEA
  • 194. The CENTERCENTER of distribution = 4% 6 8 12 14 16% MEDIANMEDIANNUMBEROFSTUDIES PERCENTAGE OF PATIENTS WITH DIARRHEA 10
  • 195. MODEMODE (most COMMONCOMMON result) = 10%10% MEDIANMEDIAN (the CENTERCENTER of distribution) = 10%10% NUMBEROFSTUDIES PERCENTAGE OF PATIENTS WITH DIARRHEA DETERMINE RESULTS OF STUDYDETERMINE RESULTS OF STUDY 4 6 108 12 14 16%
  • 196. ““10% of patients will develop diarrhea while10% of patients will develop diarrhea while taking Antibiotic A.”taking Antibiotic A.” NUMBEROFSTUDIES PERCENTAGE OF PATIENTS WITH DIARRHEA 104 6 8 12 14 16% CONCLUSION
  • 197. 4 6 8 12 14 16 NUMBEROFSTUDIES PERCENTAGE OF PATIENTS WITH DIARRHEA Wait… What about the other 15 study groups? You can’t just ignore them! 10 Or can you?
  • 198. 4 6 8 12 14 16 PERCENTAGE OF PATIENTS WITH DIARRHEA Wait… What about the other 15 study groups? You can’t just ignore them! 10 Or can you? 15 groups x 50 per group = 750 patients (75%!)
  • 199. 4 6 8 12 14 16 PERCENTAGE OF PATIENTS WITH DIARRHEA Wait… What about the other 15 study groups? You can’t just ignore them! 10 Or can you? Studies must account for ALL patients
  • 200. 4 6 8 12 14 16 NUMBEROFSTUDIES PERCENTAGE OF PATIENTS WITH DIARRHEA Wait… What about the other 15 study groups? You can’t just ignore them! 10 Or can you? Results should not be ignored, but STATISTICAL SIGNIFICANCE may be questioned.
  • 201. NUMBEROFSTUDIES PERCENTAGE OF PATIENTS WITH DIARRHEA 4 6 8 12 14 1610 My head is starting to feel heavy… So, how is STATISTICAL SIGNIFICANCE determined?
  • 202. PROBABILITY is determined by it. CHANCE is not related to it at all! STATISTICAL SIGNIFICANCESTATISTICAL SIGNIFICANCE How is it determined?How is it determined?
  • 203. PERCENTAGE OF PATIENTS WITH DIARRHEA Let’s use our study on “Antibiotic A” as the exampleLet’s use our study on “Antibiotic A” as the example 4 6 8 12 14 16%10 NUMBEROFSTUDIES 20 groups were tested.20 groups were tested. Only 1 of 20 groups landed at each end of the Bell Curve….Only 1 of 20 groups landed at each end of the Bell Curve…. WHY?WHY? SAMPLESAMPLE VARIATION?VARIATION? or CHANCE?or CHANCE?
  • 204. PERCENTAGE OF PATIENTS WITH DIARRHEA ““There is aThere is a 1 in 20 chance1 in 20 chance that other patientsthat other patients will land in these categories.”will land in these categories.” But thatBut that wouldwould NOTNOT be a correctbe a correct statement!statement! It is tempting to say,It is tempting to say, 4 6 8 12 14 16%10 NUMBEROFSTUDIES
  • 205. PERCENTAGE OF PATIENTS WITH DIARRHEA ““There is aThere is a 1 in 20 chance1 in 20 chance that other patientsthat other patients will land in these categories.”will land in these categories.” Why?Why? BecauseBecause CHANCECHANCE can not becan not be used toused to predictpredict futurefuture results!results! It is tempting to say,It is tempting to say, 4 6 8 12 14 16%10 NUMBEROFSTUDIES
  • 206. CHANCECHANCE is based onis based on RANDOMRANDOM possibility.possibility. Example:Example: THE COIN TOSSTHE COIN TOSS Coins tossed: 20 “Heads” 17 (85%) “Tails” 3 (15%) Statistical SignificanceStatistical Significance:: ZERO!ZERO! The next coin toss will still produce a random result!The next coin toss will still produce a random result! Random results can not be used to calculate Statistical Probability.
  • 207. 4% 6 8 12 14 16%10 ““There is aThere is a 1 in 20 chance1 in 20 chance that patients willthat patients will land in one of these two categories.”land in one of these two categories.” So instead of measuring “chance”…So instead of measuring “chance”… PERCENTAGE OF PATIENTS WITH DIARRHEA 1 in 201 in 20 chancechance 1 in 201 in 20 chancechance
  • 208. 4% 6 8 12 14 16%10 We need to determine theWe need to determine the PROBABILITY!PROBABILITY! 1 in 201 in 20 chancechance Translates into 5%5% probabilityprobability PERCENTAGE OF PATIENTS WITH DIARRHEA ““There is aThere is a 5% probability5% probability that patients willthat patients will land in one of these two categories.”land in one of these two categories.”
  • 209. 4% 6 8 12 14 16% There is aThere is a 5% probability5% probability that 4% ofthat 4% of patients willpatients will developdevelop diarrhea ondiarrhea on Antibiotic A.Antibiotic A. There is aThere is a 5% probability5% probability that 16%ofthat 16%of patients willpatients will developdevelop diarrhea ondiarrhea on Antibiotic A.Antibiotic A. 10 PERCENTAGE OF PATIENTS WITH DIARRHEA The results now look like this:The results now look like this:
  • 210. 4% 6 8 12 14 16%10 1 in 201 in 20 chancechance ProbabilityProbability == 5%5% PERCENTAGE OF PATIENTS WITH DIARRHEA FRACTIONFRACTION PERCENTAGEPERCENTAGE And now… Let’s abbreviate it some more!And now… Let’s abbreviate it some more! p = 0.05p = 0.05 Translates to DECIMELDECIMEL
  • 211. 4% 6 8 12 14 16%10 1 in 201 in 20 chancechance PERCENTAGE OF PATIENTS WITH DIARRHEA FRACTIONFRACTION PERCENTAGEPERCENTAGE p = 0.05p = 0.05 Translates to DECIMELDECIMEL ……by changing “by changing “% probability% probability” to” to the “the “p valuep value”” ProbabilityProbability == 5%5%
  • 212. 4% 6 8 12 14 16%10 1 in 201 in 20 chancechance PERCENTAGE OF PATIENTS WITH DIARRHEA p = 0.05p = 0.05 Translates to FRACTIONFRACTION DECIMELDECIMEL PERCENTAGEPERCENTAGE The “The “p valuep value” is statistically important!” is statistically important! ProbabilityProbability == 5%5%
  • 213. 4% 6 8 12 14 16%10 1 in 20 “chance” p = 0.05p = 0.05 It determines statistical PROBABILITY.It determines statistical PROBABILITY. ““p value”p value” ProbabilityProbability == 5%5%
  • 214. 4% 6 8 12 14 16%10 PROBABILITY vs CHANCEPROBABILITY vs CHANCE ……bbut PROBABILITYPROBABILITY is very important! It tells us the likelihood that something will happen. So, CHANCECHANCE has ZERO significance PERCENTAGE OF PATIENTS WITH DIARRHEA NUMBEROFSTUDIES
  • 215. ““There is aThere is a 5% probability5% probability that our study patientsthat our study patients will fall into either of these categories.”will fall into either of these categories.” OUR PROBABILITY STATEMENTOUR PROBABILITY STATEMENT p = 0.05p = 0.05 p = 0.05p = 0.05 PERCENTAGE OF PATIENTS WITH DIARRHEA 4 6 108 12 14 16%
  • 216. Anything less than 5% (p= 0.05)Anything less than 5% (p= 0.05) MAYMAY be due to chance.be due to chance. THAT IS A LOW PROBABILITY!THAT IS A LOW PROBABILITY! p = 0.05p = 0.05 p = 0.05p = 0.05 PERCENTAGE OF PATIENTS WITH DIARRHEA 4 6 108 12 14 16%
  • 217. 4 6 108 12 14 16% p = 0.01p = 0.01p = 0.01p = 0.01 And anything less than 1% (p= 0.01)And anything less than 1% (p= 0.01) isis MOST LIKELYMOST LIKELY due to chance!due to chance! THAT IS A LOW PROBABILITY!THAT IS A LOW PROBABILITY!
  • 218. Anything less than 5% (p= 0.05)(p= 0.05) MAY be due to chance. THAT IS A LOW PROBABILITY!THAT IS A LOW PROBABILITY! 4 6 108 12 14 16% p = 0.01p = 0.01p = 0.01p = 0.01 Anything less than 1% (p= 0.01)(p= 0.01) is MOST LIKELY due to chance. p = 0.05p = 0.05 p = 0.05p = 0.05
  • 219. (p= 0.05)(p= 0.05) becomesbecomes VERY SIGNIFICANTVERY SIGNIFICANT But when compared to another study…But when compared to another study… 4 6 108 12 14 16 And (p= 0.01) becomesAnd (p= 0.01) becomes HIGHLY SIGNIFICANTHIGHLY SIGNIFICANT!! 18%
  • 220. (p= 0.05)(p= 0.05) becomesbecomes VERY SIGNIFICANTVERY SIGNIFICANT But when compared to another study…But when compared to another study… 4 6 108 12 14 16 And (p= 0.01) becomesAnd (p= 0.01) becomes HIGHLY SIGNIFICANTHIGHLY SIGNIFICANT!! 18%
  • 221. 4% 6 108 12 14 16 Antibiotic AAntibiotic A NUMBEROFSTUDIES PERCENTAGE OF PATIENTS WITH DIARRHEA 18%
  • 222. 4% 6 108 12 14 16 Antibiotic BAntibiotic B NUMBEROFSTUDIES PERCENTAGE OF PATIENTS WITH DIARRHEA 18%
  • 223. (p= 0.05)(p= 0.05) becomesbecomes VERY SIGNIFICANTVERY SIGNIFICANT DIFFERENCE = STATISTICALLY SIGNIFICANTDIFFERENCE = STATISTICALLY SIGNIFICANT 4 6 108 12 14 16 And (p= 0.01) becomesAnd (p= 0.01) becomes HIGHLY SIGNIFICANTHIGHLY SIGNIFICANT!! 18%
  • 224. The P valueThe P value Measures ProbabilityMeasures Probability How often is this finding expected to occur? Determines Statistical SignificanceDetermines Statistical Significance What is the likelihood these findings are TRUE or FALSE? Do the comparative findings show a significant difference? Meaningful ranges p >0.05 Not significant p <0.05 Statistically SIGNIFICANT p <0.01 HIGHLY SIGNIFICANT! Does probability provide PROOF?Does probability provide PROOF? NO! We could be misled by it. The sample size is very important when determining probability!
  • 225. SAMPLE SIZE and PROBABILITYSAMPLE SIZE and PROBABILITY EXAMPLE: 100 pieces of fruit are in a bin: APPLES and ORANGES You close your eyes and pick 10 of them: Question: Does your sample accurately represent what is in the bin?
  • 226. Answer: No! Larger samples provide a closer approximation of theLarger samples provide a closer approximation of the populations they represent... But the only way to getpopulations they represent... But the only way to get 100% proof is to examine “all of the fruit in the bin!”100% proof is to examine “all of the fruit in the bin!”
  • 227. The P valueThe P value Meaningful ranges p >0.05 Not significant p <0.05 Statistically SIGNIFICANT* p <0.01 HIGHLY SIGNIFICANT!** *Significance only means that CHANCE is an unlikely explanation for the results LIMITATIONLIMITATION The p value determines LIKELIHOOD… Not proof!The p value determines LIKELIHOOD… Not proof! CAUTIONCAUTION Statistical significance does not necessarily imply anyStatistical significance does not necessarily imply any clinicalclinical significance!significance! EXAMPLE: Looking through a pinhole will improve vision in most people… But would this be an appropriate treatment for your myopic patients? (Key Topics in EBM )
  • 229. THE FIVE BASIC STEPS OF EBM 1. Clinical Question Patient-focused, problem-oriented 2. Find Best Evidence Literary Search 3. Critical Appraisal Evaluate evidence for quality and usefulness 4. Apply the Evidence Implement useful findings in clinical practice 5. Evaluate The information, intervention, and EBM process
  • 230.
  • 231. PATIENT PHYSICIAN INFORMATION Question or Problem (The Three Major Components of EBM)(The Three Major Components of EBM)
  • 236. PATIENT Recognize: Needs Choices Preferences Values Socioeconomic concerns INFORMATION Help the patient to understand and interpret available information PHYSICIAN Respect the personal priorities of the patient Help the patient to negotiate a decision on intervention, treatment CONFLICT?CONFLICT? SEPARATE THE ISSUES!SEPARATE THE ISSUES!
  • 237. PATIENT INFORMATIONPHYSICIAN PATIENT And then help theAnd then help the patient pull it allpatient pull it all together againtogether again
  • 238. KEY POINTSKEY POINTS PARADIGM SHIFT OLD: Doctor had authority (despite the pile of unread journals!) NEW: Current Best Evidence leads medical practice but it MUST be individually applied THE INDIVIDUAL PATIENT Every patient is different. Treat YOURS and not others The “ideal” course of action is not necessarily best for THIS patient. EBM + Psychosocial factors = THIS patient should be advised to take THIS therapy at THIS point in time.
  • 239. THE FIVE BASIC STEPS OF EBM 1. Clinical Question Patient-focused, problem-oriented 2. Find Best Evidence Literary Search 3. Critical Appraisal Evaluate evidence for quality and usefulness 4. Apply the Evidence Implement useful findings in clinical practice 5. Evaluate The information, intervention, and EBM process
  • 240. INFORMATION Adequate resources? Ease or Difficulty of finding and getting desired information? Costs? INTERVENTION Patient response or acceptance? Ease or Difficulty of Application? Clinical outcomes? EBM PROCESS EFFECT ON PRACTICE Will this particular experience change our thinking or practice? SELF EVALUATION How did we do? (Question, Search, Appraise, Apply) How could we improve our own EBM performance? Evaluate
  • 241. EBM: PROS, CONS and LIMITATIONS
  • 242. PROS Clinicians update knowledge base routinely Improved understanding of research methods Physician becomes more critical in use of data Increased confidence in management decisions Increased computer literacy, data search technology Better reading habits Provides framework for group problem solving, team generated practice
  • 243. Transforms weakness or paucity of knowledge into positive change OK to be uncertain OK to be skeptical OK to be flexible Integrates medical education, research and clinical expertise Can be learned by non-clinicians – other HCWs, patient groups, purchasers, etc. Allows us to keep up with our better-educated patients!
  • 244. Increased contribution of junior MDs Increased patient benefit Better communication with patients re: rationale of management decisions Promotes better and more appropriate use of limited resources May reduce costs or medical care or practice by eliminating outdated or unnecessary factors Can be learned at any stage of physician’s career
  • 245. CONS Time consuming Information overload Time to learn and practice Time may be needed for team conferencing, planning and review Takes $$$ to establish resource infrastructure – library, office, etc. computers, peripherals
  • 246. Internet costs Programs, software information, CD-ROMS Subscription costs – online and paper resources May increase cost of care (but hopefully offset by elimination of unnecessary medical interventions, tests, journals, etc. – plus save time in getting proper intervention) Online references made to unavailable journals or references Exposes gaps in the evidence (but provides ideas for researchers!)
  • 247. Requires computer skills (but can be done with minimal computer literacy and skill) May expose your current practice as obsolete or dangerous (loss of authority and respect)
  • 248. LIMITATIONS Lack of evidence (shortage of studies) Difficulty applying evidence to care of a particular patient Barriers to the practice of high quality medicine Lack of skills (search, appraise, etc.) (foster development of new skills!) Lack of time to learn and practice EBM (promotes lifelong learning thru better focus) Lack of physician resources for instant access to evidence (EBM has worldwide applicability)
  • 249. RESTRICTED AVAILABILITY OF LAB TESTS NON-TEXTBOOK CASE co morbidity, additional risk factors AFFORDABILITY (MD & PT)“I can’t afford to practice EBM.” Language barriers – available evidence may be unreadable, should be included
  • 250. Physician attitude: Can be the greatest limitation! “It decreases the importance of my clinical expertise” (that’s a necessary component!) “It only applies to those involved in research.” (promotes cooperation among multiple physicians) “It ignores patient values and preferences.” “It’s just another cookbook approach to medicine.” “It’s a poorly disguised way to cut medical costs.” (cost of care may actually increase) “It’s a way to ration care and resources.” (Provides better utilization of avail resources)
  • 251. DISAGREEMENT Pt’s comfort, choice, acceptance, values preferences Vs MD’s recommendations DOES RISK OR SIDE EFFECTS OF TREATMENT OUTWEIGHT THE BENEFITS?
  • 252. The unanswered question… “DOES EBM REALLY MAKE A DIFFERENCE?” Effect of practicing EBM on patient outcome is actually unknown – no studies done EBM good based on population studies: (ie: Pts who rec’d ___ generally fare better than those who don’t)
  • 253.
  • 254. EBM IN DEVELOPING COUNTRIES LIMITED RESOURCES May help to eliminate unnecessary or poor quality screening tests (ie: resting EKG to screen for CAD = high false negative and false positive rates) LIMITED DRUG REGULATION Approval for drug marketing easy - promotes insurgence of new drugs for questionable indications, limited effectiveness, false claims, inflated prices based on ad response (include “more expensive is better”)
  • 255. EBM IN DEVELOPING COUNTRIES LIMITED CAPACITY FOR CME Drug companies - may sponsor meetings that are little more than captive marketing sessions or biased education sessions (drug education vs promo) Result may be push for more expensive, less effective treatments (ie push for CCB’s over BB’s) - calc channel blockers over Beta Blockers
  • 256. EBM IN DEVELOPING COUNTRIES LIMITED ACCESS TO LITERATURE DATABASES Desktop computer with CD ROM reader and modem ($900) Electricity 1 yr subscription to MedLine on CD ROM (?500) Internet connection $25/mt Convince administrators of expense: Publicly cite how searches help with lectures, research and patient care management decisions Get equipment from drug companies (usually strings attached)
  • 257. EBM IN DEVELOPING COUNTRIES LIMITED ACCESS TO ADEQUATE LIBRARY FACIILITIES ALMOST INEVITABLE IN DEVELOPING COUNTRIES Identify resources via search, but then unable to retrieve articles! A top EBM practitioner (Philippines) recommends: 1. Top 3 medical libraries in your country 2. Multinational drug company libraries 3. Friends and colleagues - including in other countries
  • 258. EBM IN DEVELOPING COUNTRIES QUESTIONABLE APPLICABILITY OF ARTICLES RETRIEVED Article describes a treatment that worked in one country, but seems impossible in yours Check… • Are there pathophysiologic differences? • Will patient differences diminish the treatment response? • Patient compliance issues? • Provider compliance issues? • Co-morbid conditions which will alter the benefits or risks?
  • 259. EBM IN DEVELOPING COUNTRIES OBSTACLES TO TEACHING OR LEARNING EBM Your Hospital or Institution does not reimburse for time spent on Continuing Medical Education programs The standard 5-day workshop would be far too costly to provide or attend! Need to learn the basics - computer skills, etc. TRY THESE! Combine efforts to learn more and practice EBM with handful of colleagues (small group learning) Ask about basis for information provided by drug reps, medical supply companies, etc. It will prompt them to provide you with on the spot teaching and better information, too!
  • 260. EBM LIBRARY BASIC REQUIREMENTS Convenient – easy access at point of contact with patient if possible Current – Up to date information Electronic Database – Should be included • Online • CD-ROM
  • 261. ELECTRONIC DATABASES Evidence-Based Medicine Reviews (EBMR) – from Ovid (ovid.com) - combines Cochrane, Best evidence, Evidence Based Mental health, EB Nursing, Cancerlit, healthstar, AIDSline, Medline, and journal links (Described by one EBM specialist as “the best”) Cochrane Library – “Gold Standard” for systematic reviews Best Evidence Medline – world’s largest, free resource – over 10 million references
  • 262. PERSONNEL Medical Librarian Informatics Specialist “We can learn a great deal about current best information sources from librarians and other experts in medical informatics, and should seek hands-on training from them as an essential part of our clinical training.” (ch 2 p29-30 – Blue circled 2)
  • 263. PRINTED RESOURCES TEXTBOOKS most obsolete! Some updated yearly, plus heavy references and scientific evidence for support Clinical Evidence (BMJ Publishing Group & ACP – 1999- present) Evidence-Based On Call (http//cebm.jr.ox.uk/eboc/eboc.html) Up To Date (General medicine, CD format, Medline abstracts used for evidence) Scientific American Medicine – limited references from Medline, Harrisons
  • 264. JOURNALS Traditional Journals subject to author submissions specialists need to read and evaluate may subscribe to services that send articles of interest to your specialty timely, instant information at time of publication Ex: NEJM, Clinical Nephrology, etc. Evidence Based journals selects best studies from multiple journals of interest, summarizes best evidence Good for use by generalists Lag time from original publication: 3-6 months Ex: Evidence Based Medicine, Evidence Based Nursing, Evidence Based CV Medicine, etc.
  • 265. SPECIAL RESOURCES WHO Blue trunk Hinari PATIENT RESOURCES Medical treatments www.nlm.nih.gov/medlineplus Medical guidelines www.guideline.gov
  • 266. THE NEXT LEVEL: ADVANCED EBM SUMMARIZE AND STORE INFORMATION Future reference SHARING INFO Local Colleagues Author paper TEACHING New skills or treatments EBM practices OTHER APPLICATIONS Care of the individual patient Team protocols Hospital or practice guidelines
  • 267. EBM in Medical Education Message to medical educators from Trisha Greenhalgh, MD, co-author of Evidence Based Health Care Workbook: “An important challenge for medical educators… is to recognize that the competent student (and clinician!) is one who knows how to cope with an immense and rapidly changing body of knowledge and not one who excels in recalling the traditional or memorizing the ephemeral. The deans of medical and nursing schools must develop an infrastructure that allows problem-based, self-directed learning methods to develop within the didactic, lecture- based curricula, which have seen no fundamental changes for two centuries or more.”
  • 268. ADVANCED EBM: ADVANCED APPLICATIONS APPLY METHODS TO… Care of the individual patient Team protocols Hospital or practice guidelines Continued Learning: problem-based approach Teaching
  • 269. SELF-DIRECTED LEARNING JAMA Series of User Guides “Clinical Epidemiology: A Basic Science for Clinical Medicine” Week-long workshops On-the-job learning (in your own practice)
  • 270.
  • 271. EVIDENCE BASED MEDICINEEVIDENCE BASED MEDICINE A new approach to clinical care and researchA new approach to clinical care and research

Notas del editor

  1. Charity – EBM not mandatory (not yet) Humility – EBM is not for those who prefer an authoritarian practice of medicine Enthusiasm – have fun with the challenge, variety and change!!!
  2. China - powdered smallpox scabs blown into sinuses, pills made from cow fleas swallowed India and Istanbul - smallpox scabs applied to the scarified skin of healthy (variolation) 1717 Lady Montague has son “ingrafted by court physician, later tests orphans,prisoners
  3. Were those extremes due to true sample variation? Or chance?