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Evidence Based Medicine: PICO

Utilization of the PICO framework to improve searching PubMed for clinical questions.

Tips for PICO Search

Start your search broadly, beginning with only the P and the I elements.

Do not include the O element in your initial search unless you must, ie. if the number of results from the P and I search is too huge to peruse.

Scope out the databases you plan to use. Find a few relevant studies and examine the complete references to identify two items:

  1. Subject headings the database indexers used to describe the studies

       2.  Keywords in the articles' abstracts.

Add the relevant terms to your Search.

Search for one term at a time. After you have searched for each P element, connect those related terms with the Boolean "OR." Repeat for the I element.

To link the P and I elements of your question, combine the complete P results set and the complete I results set with the Boolean "AND."

Limit the results by study design, working your way down the evidence pyramid.

If need be, search for your question's O element and link it with the P and I elements.


  • Patient, Population or Problem

               What are the characteristics of the patient or population?

               What is the condition or disease you are interested in?

  • Intervention or exposure

       What do you want to do with this patient (e.g. treat, diagnose, observe)?

  • Comparison

               What is the alternative to the intervention (e.g. placebo, different drug, surgery)?

  • Outcome

               What are the relevant outcomes (e.g. morbidity, death, complications)?

Find Evidence using PICO

Search Strategy for PICO

 1. Frame your question:

Example: Does hand washing among healthcare workers reduce hospital acquired infections? 

The PICO elements in the question:

P (Problem or Patient or Population) hospital acquired infection
I (intervention/indicator) hand washing
C (comparison) no hand washing; other solution; masks
O (outcome of interest) reduced infection

2. Search Strategy

Natural Language Term Mapped to Database Vocabulary
P (Problem/Patient/Population)
Hospital acquired infection

Cross infection [MeSH]

Cross infection [CINAHL]

I (intervention/indicator)=Hand washing

Hand disinfection [MeSH]

Handwashing [CINAHL]

A simple database search strategy should begin with the P AND I:   

cross infection
AND  (Handwashing OR Hand disinfection) 

Start with  CINAHL/Medline or PubMed as initial article databases for a scoping search for most questions.

3. Review the initial search results and decide to narrow your search with terms for the Comparison, Outcome, Time factors or Type of study. OR you may view results, abstracts, and full text of articles to view the comparison and outcome elements.