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PICO Questions

Search Strategy

Using PICO to Plan Your Search Strategy

Now that you have formulated your PICO question, you will want to frame your search strategy for the most effective and efficient search. Start with your Intervention. If you do not find studies on your intervention, you will not have a searchable question. This occurs if the intervention is very new and not reported in the literature yet, or if the terminology is different from the term you are using in your search. You will want to combine keywords and subject headings in your strategy. Use the table below to help plan your search.

Let's look at a sample PICO question:
In adults with mild depression, does St. John’s Wort, compared to prescription antidepressants, reduce symptoms of depression?


Note: The * symbol tells the computer to truncate that term, so depress* will search for depress, depressed,  depression, depressive. The + symbol in CINAHL explodes the CINAHL Heading, so Affective Disorders+ will also search Depression, Depression Postpartum, Depression Reactive, Dysthymic Disorder. When using the OR Boolean operator, use parentheses to group those concepts together.

Below find a plan for searching this question in databases that are available either at the CORE Library or that are linked to from the CORE Library.  




CINAHL Headings

(See CINAHL Research Guide for more info)


 MeSH Terms

(See the PubMed Tips & Tricks Guide for more info on MeSH)


PsychArticles Thesaurus

(See PsycArticles Guide for more info on the thesaurus)


St John’s Wort

St john’s wort

St. John’s Wort


(hypericum OR st johns wort)

hypericum perforatum




Antidepressive Agents+

Antidepressive Agents




Symptoms of depression


Affective Disorders+

(depression OR depressive disorder)


depression (emotion)



Limiter: Ages: All Adult

Filter: Adult: 19+ years


English, Research Articles,

Publication date

Clinical Trial, Comparative Study, Meta-Analysis, Evaluation Studies, Practice Guideline, Systematic Reviews, published in the last 5 years, English, Adult: 19+ years.


Conduct your searches

Now that you have your strategy planned, you are ready to start your search. Here are some tips for a successful search:

  • Select the most appropriate database. In nursing the premiere databases are PubMed, andCINAHL. The Cochrane Library will contain Systematic Reviews, which are considered the highest level of evidence in EBP.  Some specialty databases, like PsycInfo and ERIC may also be useful.
  • You can also use the PICO search box, available within the CORE Library to search all databases using your PICO question.


The PICO search box is located below the search box on any results page.

  • Start with terms that represent your intervention.
  • Add another concept in your PICO question, such as the comparison or the outcome.
  • If your search is not relevant, revise your terms.
  • Use Boolean Logic, truncation and phrase searching when appropriate
  • Check relevant citations for subject headings. When you find one, you can click on the term to get a list of all articles in the database with that term, then add additional keywords.
  • Searching directly from the MeSH Terms or CINAHL Headings database will allow you to flag your term as a Major focus of the article or use the subheadings to focus on a specific aspect of the concept, such as prevention & control or education.
  • Use the Filters/Limiters to focus your search. This will help you create a customized set that is written in English, published within a certain date range, the publication type to limit to studies, and the appropriate age range. You may want to include systematic reviews and practice guidelines as a publication type.
  • Now you are ready to select the articles you wish to critically appraise.
  • Going through this process will reduce the number of article citation in your search retrieval, which will also reduce the time you must spend selecting relevant articles.
  • Not finding what you need? Contact the librarian for assistance.