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Phillips School of Nursing Information Commons: PICO & Searching

Successful Searching with a PICO Question

Evidence-Based Medicine: Principles for Applying the Users' Guides to Patient Care 

Developing a Search Strategy: Literature Searching Explained by the University of Leeds

Well Built Clinical Question: PICO Worksheet

Identify Core PICO Elements:

The PICO framework is often recommended as a way to structure and focus on clinical questions. PICO can make it easier to identify search concepts and appraise the results retrieved from database searches.

PICO stands for

  • Patient and Problem 
  • Intervention or exposure
  • Comparison or Control
  • Outcome

When you break down your question using PICO, keep the following points in mind:

Patient is a member of a population as well as a person with (or at risk for) a health problem. In addition to age and sex, you may also need to consider ethnicity, socioeconomic status or other demographic variables when you look for and evaluate the evidence.

Intervention is the management strategy, diagnostic test, or exposure that you are interested in (drug, treatment, diagnostic test or screening). 

Comparison is not always present in a PICO analysis. If you are evaluating the utility of a diagnostic test, though, you will need to compare the new test to the "reference standard".

Outcomes should be measurable: the best evidence comes from rigorous studies with statistically significant findingsOutcomes ideally measure the quality of life or clinical well being, and not surrogate markers such as laboratory test results.


Literature Searching

Successful literature searches tend to have simple search statements that include only two to three core concepts. Beginning EBM searchers often make the mistake of trying to incorporate every concept from their PICO analysis in their search query — which often results in few or no search results. In general, start your search with no more than three search concepts. These concepts should reflect your question's most important PICO elements. To help set priorities, some suggest underlining the key terms in your search statement and others recommend listing them in rank order of importance

Once you have identified the main concepts of your question, you'll need to choose good search terms to represent those concepts. Unsuccessful or incomplete searches are often caused by using overly specific terms or subject headings, or by the failure to specify alternate terms when the initial search fails. 

Search Tip: Start with broader concepts

For example, begin searching with cardiac arrhythmia AND anticoagulation. Then, if you retrieve too many results, use more specific concepts (atrial fibrillation AND warfarin).

Search Tip: Identify alternative ways to express your main concept

Connect synonyms or related concepts with OR (e.g., warfarin OR anticoagulants OR coumarins).

Example of Database Search with One Term

Example of Database Search with Two Terms

Boolean Operators

Boolean Operators link concepts and are used to broaden or narrow your search. Briefly, here's how they work:

AND - finds results with both keywords. AND narrows your search. The advanced search in most databases defaults to automatically use AND between the search boxes. 

  • Example: in a  search for gene AND expression you will find records where both the word gene and the word expression appear. 

OR - finds results with either of the keywords. OR broadens your search.

  • Drug Effect OR Drug Effects OR Adverse Effects etc. will search for all terms. 

NOT - excludes items that use the keywords. NOT narrows your search.

  • pregnancy NOT teen 

Using Boolean's: Connecting Terms

For best results, only use the OR within a search box. The AND is placed automatically between the search boxes.

An example search for evidence-based practice in nursing research might look like this:

First search box: nursing research OR nursing education 

Second search box: evidence-based practice OR evidence-based medicine 

Truncation & Phrase Searching

Phrase Searching: 

Enclose the phrase using double quotation marks (i.e. "shift handoff") in order to find citations that have those words in the exact order. Gets fewer citations. 

  1. patient falls finds 2,619 citations
  2. "patient falls" finds 483 citations

Truncation is a search method in which symbols are used in place of letters or words to help you broaden your search (i.e., get more citations).  

The asterisk (*) represents any group of characters, including no character. Use it at the end of the root of your term.

  1. prevent* finds prevent, preventative, prevented, preventing, etc.
  2. smok* finds smoke, smokeless, smoker, smoking, etc.