Advanced PubMedEBP: Searching Clinical Questions
Jessica Cole, MLIS, AHIPPHA 520November 19, 2013
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.”
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
Don’t Expect Research to be a Linear
Process!
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
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
QuestionSearch Strategy
Transition from Step 1. Asking the Question to Step 2.
Acquiring evidence:
Planning the database search strategy
1. ASK
Planning the Search
In the elderly, does Tai Chi reduce the number of accidental falls?
2. ACQUIRE
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
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
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
Planning the Search
Keywords vs. MeSH
(Medical Subject
Headings)
Strengthen a search by using
terminology the database
understands!
2. ACQUIRE
Cola, Pop, Soda, Coke, Soda Pop? Bill, Money, Dollar, Cash,
Currency?
2. ACQUIRE
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
Find “Best” Search Terms2. ACQUIRE
A search for “fall” in the MeSH Database displays the
appropriate MeSH term, “Accidental Falls.”
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
(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
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
Conduct the Search 2. ACQUIRE
Conduct the Search 2. ACQUIRE
Age filters can be
applied after the
search, or you can
search the term
“Aged”
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
Filters: Levels of Evidence
Filters for types of evidence can also be
applied now.
2. ACQUIRE
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
Review ResultsAppraise
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
Save “Good” Articles 2. ACQUIRE
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
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
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 of cost and risk of harm?
Users' Guide to Medical Literature: A Manual for Evidence-Based Clinical Practice, 2nd Edition.
3. APPRAISE
Critical Appraisal
Critical appraisal information at JAMA
Evidence
3. APPRAISE
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?
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] ANDI: Serotonin uptake inhibitors [MeSH searched as keyword] ANDC: (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
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.
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.
