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Nursing and Public Health: PICO & Search Terms

Framing the Research Question: PICO

One great way to find evidence-based models for nusing is called the PICO Method. This is a process for framing a question, locating, assessing, evaluating, and repeating as needed. PICO stands for:

  • Problem/Patient/Population
  • Intervention/Indicator
  • Comparison
  • Outcome

Frame the question: Write out your information need in the form of a question, for example:

   Does hand washing among healthcare workers reduce hospital acquired infections?

The question above includes the PICO elements:

PICO Elements

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


  • By identifying the major elements of your question, and translate natural language terms to subject descriptors, MeSH terms, or CINAHL descriptors. 

  • Start with the P and the I only to begin your search and keep initial search results broad:
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  AND:

cross infection AND  (Handwashing OR Hand disinfection) 

Start with both CINAHL and Medline/PubMed as initial article databases for a scoping search for most health sciences questions.  If your topic has a behavioral/mental health component, also try PsycINFO, PsycArticles, ProQuest Psychology, or PTSDpubs.

Link to a detailed search:
Does hand washing among healthcare workers reduce hospital acquired infections?

After viewing the initial search results you may 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. Use database filters, explained in Filtering the Evidence. 

The following guides are courtesy of New York University (NYU):

*Heneghan, C., & Badenoch, D. (2002). Evidence-based medicine toolkit. London: BMJ Books

Search terms

Boolean Search Terms

It is vital to using the right search terms to describe your key concepts. It is often helpful to look at your preliminary search results for more words or phrases that you can later include in your search. Be prepared to adapt and refine your search as you go along in order to make the results more precise.

Use synonyms (similar words), antonyms (opposite words), related words, acronyms, abbreviations and different terminology to improve your search.  Using a thesaurus will help.

Keep your search clean and lean - avoid using vague words and phrases like the following  as these are not key concepts and are rarely helpful in searching.

  • “The role of”
  • "The impact on”
  • "The effectiveness of..."
  • "The affect on"

These techniques help to improve your search strategy and can make a significant difference to your search results. Always check the database help pages before you start searching for more specific advice.

  • Truncation and wild cards - useful for finding singular and plural forms of words and variant endings. Shorten your keyword to its "stem" or "trunk" and add the truncation symbol.
  • Phrase and adjacency searching – databases offer specific techniques for searching for phrases and words in close proximity.
  • Searching with subject headings – using the controlled vocabulary that a database uses to classify what an article is about.
  • Boolean operators - Boolean operators (AND, OR and NOT) allow you to combine search terms in different combinations.  

OR – broadens and is usually used to combine synonyms or “like” words to make results more comprehensive.

AND – narrows and is usually used to combine different concepts to make results more relevant.

NOT – narrows by reducing the number of results you retrieve by excluding a search term.