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Advanced PubMed EBP: Searching Clinical Questions Jessica Cole, MLIS, AHIP PHA 520 November 19, 2013

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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


2. ACQUIRE-Find best evidence to answer


3. APPRAISE-Critically appraise evidence.

4. INTEGRATE evidence with clinical expertise

& patient values to apply in practice.

5. EVALUATE performance. Database Searching


Don’t Expect Research to be a Linear


Define Research Question

Convert the information need into a specific

question. This will guide your research


Convert question to PICO format to help you

break it down and plan a database search


Determine “best” concepts/terms to represent

each PICO element. These are the terms you

will string together to build your database


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?


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)


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?


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.


Planning the Search

Keywords vs. MeSH

(Medical Subject


Strengthen a search by using

terminology the database



Cola, Pop, Soda, Coke, Soda Pop? Bill, Money, Dollar, Cash,



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.


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.


(P) Elderly

(I) Tai Chi

(C) –No comparison-

(O) Reduce Falls

Aged (or use age



(Tai Chi OR Tai Ji)


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


Examples: Age groups, gender


Conduct the Search 2. ACQUIRE

Conduct the Search 2. ACQUIRE

Age filters can be

applied after the

search, or you can

search the term


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!


Filters: Levels of Evidence

Filters for types of evidence can also be

applied now.


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:


Review ResultsAppraise

Transition from Step 2. Acquiring the

evidence to Step 3. Critically appraise the

evidence – Overlap.

SAVE “good” results as you


Even if you are not yet critically appraising

individual articles while scanning results,

hold onto those that look promising.


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.


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.


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.


Critical Appraisal

Critical appraisal information at JAMA




1. ASK



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


Examine MeSH terms for ideas for terms to


Also view Related Citations.

PubMed Search Tips


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



Add more search terms with AND. Use filters/limits to narrow results.


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.

Contact Your Librarian for Help!

[email protected]