Faculty of Health and Medical Sciences

Find the best evidence

Converting your clinical question into a search strategy

Your well-built clinical question acts as a structured check-list for concepts to include in your search.

To search effectively and efficiently it is helpful to use a search strategy construction tool such as PICO. To use PICO follow the steps below.

Click on each of the tabs to find out more.

Step 1: Identify your search terms

  • Break your question down to the main concepts.
  • Identify keywords and synonyms from the clinical question.

For example:

In patients with septic shock does treatment with steroids compared with no steroids alter outcome as reflected in morbidity?

Patient Intervention Comparator Outcome
sepsis steroids no steroids morbidity

What other terms could represent these concepts? A thesaurus can help you do this. It's useful to list the most general terms first working down to the most specific. This way you have options for narrowing your search. For example:

Patient Intervention Comparator Outcome
sepsis
septic shock
severe sepsis
Steroids
Methylprednisolone
corticosteroids
no steroids
placebo
mortality

Step 2 Combine your search terms

You need to tell the resource how you want it to look for your terms. Link these keywords, and synonyms if applicable, in a meaningful way in order to perform an effective search.  

This is done by using Boolean operators between your terms (some people find a research planner useful at this stage).

Boolean operators
AND Results contain both terms. Using AND generally limits your search.
OR Just one of these terms in the results is OK. Using OR usually broadens your search.
NOT Results exclude the subsequent term. Using NOT limits your search – use with caution.

Where do the operators go?

AND is placed between each of your major concepts to ensure they are all present in your results.  OR is used between synonyms so that all variants are included in the search (brackets are used to group variants together).

For example:

Patient Intervention Comparator Outcome
Sepsis
OR
septic shock
OR
severe sepsis
Steroids
OR
methylprednisolone
no steroids mortality