This document provides guidance on conducting evidence-based searches in PubMed to answer clinical questions. It outlines the 5 steps of evidence-based practice and focuses on steps 1 and 2 - asking questions and acquiring evidence. Readers learn how to develop a focused clinical question using PICO elements and then plan and conduct a search in PubMed using relevant keywords, Medical Subject Headings, Boolean operators and filters. The importance of critically appraising search results to determine the level of evidence is also discussed.

1. Advanced PubMed
EBP: Searching Clinical Questions
Jessica Cole, MLIS, AHIPPHA 520
November 19, 2013

2. Evidence-Based Practice
“Evidence based medicine is the conscientious, explicit, and judicious use of
current best evidence in making decisions about the care of individual patients.
The practice of evidence based medicine means integrating individual clinical
expertise with the best available external evidence from systematic research.”

3. EBP Research Steps
1. ASK-Convert information need into a
question.
2. ACQUIRE-Find best evidence to answer
question.
3. APPRAISE-Critically appraise evidence.
4. INTEGRATE evidence with clinical expertise
& patient values to apply in practice.
5. EVALUATE performance.
Database Searching
Skills

4. Don’t Expect Research to be a Linear
Process!

5. Define Research Question
 Convert the information need into a specific
question. This will guide your research
process.
 Convert question to PICO format to help you
break it down and plan a database search
strategy.
 Determine “best” concepts/terms to represent
each PICO element. These are the terms you
will string together to build your database
search.
1. ASK

6. PICO Question
Include the following PICO elements in your question
P Patient characteristics/condition
I Intervention (or diagnosis/prognosis)
C Comparison intervention (if applicable)
O Outcome of interest
In the elderly, does Tai Chi reduce accidental falls?
1. ASK

7. QuestionSearch Strategy
Transition from Step 1. Asking the Question to Step 2.
Acquiring evidence:
Planning the database search strategy
1. ASK

8. Planning the Search
In the elderly, does Tai Chi
reduce the number of
accidental falls?
2. ACQUIRE

9. Big Picture Example
1:
Fast Forward to Strategy
This is what our search strategy will look like in
the end. What follows in the next slides are the
steps taken to build this search:
In the elderly (P), does Tai Chi (I) reduce the
number of accidental falls? (O)
2. ACQUIRE

10. Big Picture Example
2:
Fast Forward to Strategy
This is another example of a search built for the
question below. For the last question, P+I+O were
searched. For this question and approach, we search
P+I+C.
In an adult diagnosed with depression(P), is St. John's
Wort (C) as effective as SSRIs (I) at reducing
depressive symptoms?
2. ACQUIRE

11. Planning the Search
 List the main terms/concepts from your PICO
question.
 Which terms are most important for the search?
 Always search for the P and I elements with the
“best” terms to capture a concept. C is optional,
depending on whether your question is comparing
two interventions. For certain questions, the
outcome O will be an important term to search,
and for others it will not.
 Example of when NOT to search for outcome: If
the P is a condition characterized by having pain
and your question is how to reduce that pain,
PAIN, is already implied.
2. ACQUIRE

12. Planning the Search
Keywords vs. MeSH
(Medical Subject
Headings)
Strengthen a search by using
terminology the database
understands!
2. ACQUIRE

13. Cola, Pop, Soda, Coke, Soda Pop? Bill, Money, Dollar, Cash,
Currency?
2. ACQUIRE

14. Planning: MeSH Database
Search your keywords in the MeSH database for
other terms more likely to be recognized by the
database. Write down the MeSH for later.
2. ACQUIRE

15. Find “Best” Search Terms2. ACQUIRE
A search for “fall” in the MeSH Database displays the
appropriate MeSH term, “Accidental Falls.”

16. Find “Best” Search Terms
When to search with “OR”
 When a term you believe is common has a
different MeSH heading.
 (Tai Chi OR Tai Ji) will retrieve results that use
EITHER term. Tai Chi is our keyword. Tai Ji is the
MeSH term.
2. ACQUIRE

17.  (P) Elderly
 (I) Tai Chi
(C) –No comparison-
 (O) Reduce Falls
 Aged (or use age
filters)
AND
 (Tai Chi OR Tai Ji)
AND
 Accidental Falls
Our Original Keywords from
Clinical Question
Decision: Terms to Search
after finding MeSH Terms
(with AND)
Find “Best” Search Terms2. ACQUIRE

18. Remember Filters!
 Many times the “P” of PICO question has
filters to apply at the end of the search so you
don’t need to search for terms like “female” or
“adolescent.”
 Examples: Age groups, gender
2. ACQUIRE

19. Conduct the Search 2. ACQUIRE

20. Conduct the Search 2. ACQUIRE
Age filters can be
applied after the
search, or you can
search the term
“Aged”

21. Apply Filters
 First see # results and review article titles
without applying the filters.
 View results with filters applied: Be aware that
filters might also remove some “good” results.
Always try both ways.
 Use filters for levels of evidence here or at a
later point of refining/appraising the search.
 Filter must show checkmark.
 Remember to clear filters!
2. ACQUIRE

22. Filters: Levels of Evidence
 Filters for types of evidence can also be
applied now.
2. ACQUIRE

23. Filters: Article Types
 Systematic Reviews/Meta-Analysis are strongest
level of evidence for most questions because they
synthesize several studies. Also see Clinical
Practice Guidelines.
 For individual studies, best design/article type is:
2. ACQUIRE

24. Review ResultsAppraise
 Transition from Step 2. Acquiring the
evidence to Step 3. Critically appraise the
evidence – Overlap.
 SAVE “good” results as you
go!
 Even if you are not yet critically appraising
individual articles while scanning results,
hold onto those that look promising.
2. ACQUIRE

25. Save “Good” Articles 2. ACQUIRE

26. Critical Appraisal
Are the results valid?
 Did intervention and control groups start with the same
prognosis? Were patients randomized?
 Was group allocation concealed?
 Were patients in the study groups similar with respect to
known prognostic variables?
 Was prognostic balance maintained as the study
progressed? To what extent was the study blinded?
 Were the groups prognostically balanced at the study's
completion? Was follow-up complete?
 Were patients analyzed in the groups to which they
were first allocated?
 Was the trial stopped early?
Users' Guide to Medical Literature: A Manual for Evidence-Based Clinical Practice, 2nd Edition.
3. APPRAISE

27. Critical Appraisal
What are the results?
 How large was the treatment effect?
 What was the relative risk reduction?
 What was the absolute risk red
 How precise was the estimate of the treatment
effect? What were the confidence intervals?
Users' Guide to Medical Literature: A Manual for Evidence-Based Clinical Practice, 2nd Edition.
3. APPRAISE

28. Critical Appraisal
How can I apply the results to patient care?
 Were the study patients similar to my population of
interest?
 Does your population match the study inclusion criteria?
 If not, are there compelling reasons why the results should
not apply to your population?
 Were all clinically important outcomes considered?
 What were the primary and secondary endpoints studied?
 Were surrogate endpoints used?
 Are likely treatment benefits worth the potential harm and
costs?
 What is the number needed to treat (NNT) to prevent 1
adverse outcome or produce 1 positive outcome?
 Is the reduction of clinical endpoints worth the increase ofUsers' Guide to Medical Literature: A Manual for Evidence-Based Clinical Practice, 2nd Edition.
3. APPRAISE

29. Critical Appraisal
 Critical appraisal information at JAMA
Evidence
3. APPRAISE

30. Summary
1. ASK
2. ACQUIRE
3. APPRAISE
First, know what you are looking for! Write a
focused clinical question based on PICO format to
help you plan your search strategy – translate your
question into the best search terms.
Conduct an Advanced PubMed search with the
best terms identified from PICO, using Boolean
operators and applicable filters to limit results.
Save good results as you go and experiment for
different sets of results. Always search P & I
concepts at minimum.Critically appraise individual articles/studies.
Upon closer examination, is it still relevant to your
PICO question? Are results valid, and have you
carefully looked for the “best” highest levels of
evidence available on this topic?

31. PICO Search Demo Video
In a 30-year-old male patient diagnosed with depression, is
St. John's Wort as effective as SSRIs at reducing depressive
symptoms?
P: Depressive disorder [MeSH searched as keyword] AND
I: Serotonin uptake inhibitors [MeSH searched as keyword] AND
C: (Hypericum [MeSH searched as keyword] OR St. John's Wort)
O: Desired outcome is efficacy, but this term is not part of the
search strategy because it is already implied in the search.
Use PubMed Advanced search builder to string these terms
together with AND (Enter the OR terms in the same line - which is
the third line in this demo, and leave the Boolean operator on the
left of the search builder as AND) Click search.
Step 3: Apply filters: English, Humans, Systematic Review
[subset]
See https://www.youtube.com/watch?v=_pVxRw-y8-M

32. Tip: How to Cheat
Find 1 relevant article and take a closer look for
clues.
 Examine MeSH terms for ideas for terms to
search.
 Also view Related Citations.

33. PubMed Search Tips
NOT ENOUGH RESULTS?
 Search synonyms with OR (i.e. aqua therapy OR aquatic exercises)
 Find one “good” article and view Related Citations & MeSH
 Remove filters. Reduce number of ANDs in search strategy (Search
P AND I)
TOO MANY RESULTS?
 Add more search terms with AND. Use filters/limits to narrow results.
DO:
 Experiment! (Keywords, Boolean operators, filters)
 Save “good” references as you go with the Clipboard/email/
 When searching with an “OR,” place the two terms on same line in
search builder so search functions properly.

34. Contact Your Librarian for Help!
Jessica.cole@nau.edu
827-2376