1. Searching the Literature
Biostats
Susan Fowler, MLIS
Medical Librarian
Fowler@wustl.edu
314‐362‐8092
pg: 314‐360‐1069

2. Outline
• Search Strategy
• Pulling Keywords from Your PICO Question
• Boolean, Truncation, and Wild Cards
• Hierarchy of Evidence and Study Design
• Google Scholar
• Cochrane Database of Systematic Reviews
• PubMed (MEDLINE)
• EMBASE

3. Choosing Appropriate Evidence
Higher Percentage of
Quality Meta‐ the Literature
analyses
Systematic
reviews
Randomized
controlled trials
Prospective blind
comparisons
Cohort studies
Case‐control studies
Case series and case reports
Animal and laboratory research
Will Olmstadt, MS, MPH

4. PICO
• Patient or problem ‐ How would I describe a group of
patients similar to mine?
• Intervention ‐ Which main intervention, prognostic
factor, or exposure am I considering?
• Comparison ‐ What is the main alternative to compare
with the intervention?
• Outcome ‐ What can I hope to accomplish, measure,
improve or affect?
Will Olmstadt, MS, MPH

5. The Search Strategy
• Develop PICO question
• Identify keywords and terms from PICO
• Identify standardized subject headings
• Combine subject headings and keywords
to narrow or broaden your search
• Evaluate your search results
• Revise the search in light of your results

6. Pulling Keywords from Your
PICO Question
• What are the main topics of your PICO?
• Brainstorm – what other words could you
use to describe your topic?
• What are some synonyms for the words
you’ve come up with?

7. Evaluate the Search Results
Don’t be afraid if you have zero (0) or thousands of results,
play around with search strategies – you wont break
anything!
– Read the titles and abstracts of “hits” in your search
to get a feel for their relevance
– Identify relevant MeSH and Keywords used to index
particularly relevant “hits”
– If your search yields too many or too few hits,
modify it and try again

8. Revise the Search in Light of
your Results
• Narrow the search by combining search
terms and applying limits
• Broaden the search if the results are too
limited by removing keywords and limits

9. Boolean
• AND
• OR
• NOT

10. Boolean
strawberry AND AND chocolate
Strickland, Jennifer and Henderson, John R. (October 10, 2005). Boolean Logic. Retrieved September 22, 2007, from
http://www.ithaca.edu/library/course/expert.html.

11. Boolean
strawberry OR OR chocolate
Strickland, Jennifer and Henderson, John R. (October 10, 2005). Boolean Logic. Retrieved September 22, 2007, from
http://www.ithaca.edu/library/course/expert.html.

12. Boolean and Nesting
(strawberry OR NOT chocolate
Strickland, Jennifer and Henderson, John R. (October 10, 2005). Boolean Logic. Retrieved September 22, 2007, from
http://www.ithaca.edu/library/course/expert.html.

13. Truncation and Wild Cards
• Truncation is a searchable shortened form of a word.
– adolescen* will include
• adolescence
• adolescent
• adolescents, etc…
• Wild card characters are useful because of alternate spellings and
other quirks in the English language.
– behavio?r, will include
• behaviour
• behavior
– Wom*n, will include
• women
• woman

14. Quotation Marks
Using quotation marks for a phrase forces the database to
return results where those words appear together.
Without Quotations = 57,360 results With Quotations = 13,180 results

15. Google Scholar
• http://scholar.google.com/
• Freely accessible database of a vast array of materials
and media archived in the web
• Customizable to point to your full text available through
your library
• Customizable to send citations to your citation manager
• Set up auto search alerts to track materials that match a
specific search query

16. Go to
“Advanced
Scholar Search”

17. Advanced Scholar Search
Use truncation
Search exact
phrases
Use limits to
narrow results by
specific author,
publication, and
date range.
Narrow by
subject area

18. Set Up Alert
Click the envelope
to access the
alert service.

19. Set Up Alert, cont…
Alerts will
automatically be
sent to your email.

20. Scholar Preferences

21. Scholar Preferences, cont…

22. Cochrane Database of
Systematic Reviews
• http://www.cochrane.org/
• “Gold Standard” for systematic reviews
• Free database, but requires paid subscription to access
most content

23. Cochrane

24. Cochrane Search
Example
Question: Does the use of Echinacea really prevent the common cold?
You are only
interested in
Cochrane Reviews

25. Cochrane Search Example cont…
You are only
interested in
Cochrane Reviews
Click “Record” to
view details of review
and access full text if
available.

26. Cochrane Systematic
Reviews
Pros
– Compiled through rigorous standards
– Review process has already been done so
you don’t have to
Cons
– Limited content
– Limited search capabilities
– Access to most full‐text content requires paid
subscription

27. PubMed (MEDLINE)
• www.pubmed.gov
• Created and maintained by the National
Institute of Health (NIH) and the National
Library of Medicine (NLM)
• 17 million citations back to 1950s
• Free database of citations with some
content available for free

28. MeSH = Medical Subject Headings
Choose MeSH from
Pull Down Menu

29. MeSH in PubMed
Enter your search terms one at a time…

30. PubMed - MeSH cont…
Choose the most
applicable
MeSH terms

31. PubMed - MeSH cont…
Send to Search Box

32. PubMed ‐ MeSH cont…
Click “Search PubMed”

33. PubMed – Advanced Search

34. PubMed – Advanced Search
Enter search numbers
and combine using
Boolean operators.

35. PubMed - Limits

36. PubMed - Limits cont…
For the most clinically applicable articles, limit to “Humans,” “English,” and “Type of Article”

37. PubMed – Limit to Type of Article
Tier 1 Tier 2
• Clinical Trial
• Meta‐Analysis • Clinical Trial, Phase I
• Practice Guideline • Clinical Trial, Phase II
• Clinical Trial, Phase III
• Randomized Controlled • Clinical Trial, Phase IV
Trial • Comparative Study
• Controlled Clinical Trial
• Review • Research Support, N.I.H., Extramural
• Research Support, N.I.H., Intramural
• Guideline • Research Support, Non‐U.S. Gov't
• Research Support, U.S. Gov't, Non‐P.H.S.
• Multicenter Study • Research Support, U.S. Gov't, P.H.S.

38. Accessing Full‐Text Articles
Avoid clicking on publisher icons unless they explicitly state that they are free or
unless you are willing to pay $ 35.00 ‐65.00 dollars per article.

39. Accessing Full‐Text Articles cont…
It is likely that your institution’s library has facilitated link‐out in PubMed to link you
directly to articles from journals to which they subscribe to.
It is also likely that your institution’s library has an Inter‐Library Loan service that will
“borrow” the article you want from another library for you for a small charge (certainly
less then $35.00!) or for free.
Contact your librarian and find out what services are available and how to use them.

40. PubMed - Send To From “Send to” drop
down menu, choose
“E‐mail”
You can email your results to yourself and your colleagues.

41. PubMed - Search History
Don’t forget to save your search history!

42. PubMed (MEDLINE)
PubMed advantages PubMed disadvantages
– Free to search – Still have to appraise articles
– No username/password once located
– Searches same content as
Ovid MEDLINE
– Links to free full‐text
sometimes available

43. EMBASE
• Over 56,000 preferred terms (of which more than 27,000
are drugs and chemicals) – more than twice as large as
MeSH
• More than 230,000 synonyms (with over 144,000 drugs
and chemical synonyms)
• Requires a paid subscription to access
• over 20 million indexed records from more than 7,000
active, peer‐reviewed journals
• over 2,000 biomedical titles not offered by Medline
• Index conference abstracts

44. EMBASE - Emtree
Click Emtree to access database of
standardized terms

45. EMBASE – Emtree, cont…

46. EMBASE – Emtree, cont…

47. EMBASE – Advanced Search

48. Good Database Searching Rules
Following these rules will improve your results…
1. Think out your query, pull out individual concepts
2. Search individual concepts alone and combine them later from search
history
3. Apply Limits to narrow your search and make it more specific to your needs
4. Keep a copy of your search history.
5. If it takes you longer then 20 minutes – ask your librarian for help.

49. Library Locations
• 660 S. Euclid • St. Louis Children’s Hospital
314‐362‐7085 Lauren Yaeger, 314‐454‐2768
Susan Fowler, 314‐362‐8092 yaegerl@wustl.edu
Pg: 314‐360‐1069
fowler@wustl.edu
• BJ North, Rothschild
Medical Library
Reka Kozak, 314‐454‐7208
kozakr@wustl.edu