1. Locating Observational
Studies and Trials
Lynn Kysh, MLIS
kysh@usc.edu
Information Services Librarian
Norris Medical Library

2. Evidence Pyramid – Publication Types
Evidence-Based
Guidelines
Systematic
Review & Metaanalysis
Higher Quality of Information
Fewer Articles
Randomized Controlled
Trials
Cohort Studies
Case Control Studies
Lower Quality of Information
More Articles
Case Series, Case Reports

3. Agenda
1. Define and locate:
a.
b.
c.
d.
Case reports & case series
Case control studies
Cohort studies
Randomized controlled trials
2. Build PubMed search skills
3. Introduce ClinicalTrials.gov
Allie Brosh - Hyperbole and a Half
http://hyperboleandahalf.blogspot.com/

4. ALL STUDIES
Descriptive
Case Report
Case Series
Analytic
Qualitative
Studies
Adapted from Derrick Bennett and John Emberson
Centre for Evidence Based Medicine
www.cebm.net

5. Case Report
Case Series
A report on an individual
patient with an outcome of
interest
A report on a series of
patients with an outcome of
interest.
• Helpful for rare or new diseases/disorders
• No control group
• Little statistical validity

6. • U.S. National Library of Medicine & National Institutes
of Health
• MEDLINE, life science journals, online books
• Over 23 million citations
• USC will connect you to full text options

7. Finding case reports and case series:
Use “Article Type” filter

8. ALL STUDIES
Descriptive
Case Report
Case Series
Analytic
Qualitative
Studies
Observational
Case-Control
Study
Adapted from Derrick Bennett and John Emberson
Centre for Evidence Based Medicine
www.cebm.net
Cohort Study

9. Case Control
Study
Compare patients with a
specific condition to
people without the
condition
Cohort Study
Identify a group of patients under
treatment or an exposure, follow
them forward over time, and then
compare their outcomes with a
similar unaffected (control) group
• Ethically safer, easier and cheaper than RCTs
• No blinding or randomization
• Hidden confounders

10. Finding case control studies and cohort
studies:
Use MeSH Terms

11. ALL STUDIES
Descriptive
Case Report
Case Series
Analytic
Qualitative
Studies
Experimental
Trials
Adapted from Derrick Bennett and John Emberson
Centre for Evidence Based Medicine
www.cebm.net
Randomized
Control Trial
Observational
Case-Control
Study
Cohort Study

12. Randomized
Control Trials
Participants are randomly allocated into an
experimental or control group and followed over
time for the variables/outcomes of interest
• Randomization
• Blinding
• Processes counteract bias
• Statistical analysis possible

13. Finding randomized control trials:
Use “Article Type” filter

14. Are all trials published?
NO.

15. •2007 FDA Amendment Act
• Drug and Device trials MUST post to
clinicaltrials.gov
• Abbreviated summary tables
• Within 1 year of completion

16. •It is not perfect...
• Only starts with trials in 2008
• Label use only
• Study from 2012 shows only 1 in 5 trials are
compliant
Prayle, A P 01/03/2012). "Compliance with mandatory reporting of clinical trial results on ClinicalTrials.gov:
cross sectional study". BMJ. British medical journal (Clinical research ed.) (0959-8138), 344, p. d7373.

17. Cannot rely on information being accurate
solely because it was published in a peer
reviewed journal

18. vs.
EBM
1. Ask
2. Acquire
3. Appraise
4. Apply
5. Assess
+ Advocate
Publication Bias
• Unreported
results
• Incomplete data
• Poorly designed
trials
• Ghost writing

19. Agenda
1. Define and locate:
a.
b.
c.
d.
Case reports & case series
Case control studies
Cohort studies
Randomized controlled trials
2. Build PubMed search skills
3. Introduce ClinicalTrials.gov
Allie Brosh - Hyperbole and a Half
http://hyperboleandahalf.blogspot.com/

20. Thanks!
Lynn Kysh, MLIS
Information Services Librarian
kysh@usc.edu
(323) 442-1124
Laney Griner
http://www.flickr.com/photos/sammyjammy/