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Physician Assistant Studies

Books, articles, and other resources for Physician Assistant students.

Introducing PICO

A clinical question needs to be directly relevant to the patient or problem at hand and phrased in such a way as to facilitate the search for an answer. PICO makes this process easier. It is a mnemonic for the important parts of a well-built clinical question. It also helps formulate the search strategy by identifying the key concepts that need to be in the article that can answer the question.


  • PATIENT OR PROBLEM:  How would you describe a group of patients similar to yours? What are the most important characteristics of the patient?
  • INTERVENTION/EXPOSURE:  What main intervention are you considering or what exposure might be impacting this population? What do you want to do with this patient?
  • COMPARISON:  What is the main alternative being considered, if any?
  • OUTCOME:  What are you trying to accomplish, measure, improve or affect?

These are not always used, but can be useful for helping to narrow your results:

  • Type of Question:  Therapy / Diagnosis / Harm / Prognosis / Prevention
  • Type of Study:  Systematic review / RCT / cohort study / case control
  • Setting:  Where was the study done (hospital, long term care facility, community, etc)



Here I'll walk you through my thinking process when I work on a PICO question.

We might start with a question like "How effective is CPR?"  PICO is a way of formalizing our question to help us (or force us) to build a question that we can investigate.  So in this case, it might look something like:

  • P -  our question above doesn't address a specific problem other than the assumption of a person who is not breathing. So, ask yourself some questions:
    • Am I interested in a specific age cohort? (Adults, children, aged) 
    • Am I interested in a specific population? (hospitalized, community dwelling)
    • Am I interested in a specific health cohort? (healthy, diabetic, etc.)   
  • I - our question above doesn't have a stated intervention, but we might have one in mind such as 'hands-only'
  • C - Is there another method of CPR that we want to compare the hands-only to?  Many research studies do not go head to head with a comparison.  In this example we might want to compare to hands plus breathing.
  • O - Again, we need to ask, what do we mean by 'effective'?  In this case, mortality might be the outcome that we measure. 

Our PICO statement would look like this:

P - community dwelling adults
I - hands only CPR
C - hands plus rescue breathing CPR
O - mortality


Now let's use our PICO question to build a search.

P - Community Dwelling:  It is much easier to search on 'hospitalized' than non-hospitalized subjects.  So I would leave these terms for last. It might turn out that I don't need to use them as my other terms from the I, C, or O of PICO might be enough.

community dwelling OR out-of-hospital

P - adults: If I'm using CINAHL, I'd use the limits for All Adults.  In PubMed, we're going to have to try to capture it with search terms.  I'd probably leave it out of my initial search unless I need to narrow my results.


I - CPR:  I happen to know that PubMed will automatically expand "CPR" to include "cardiopulmonary resuscitation", but if you are working on something that is an acronym or abbreviation, you should think about expanding it to include all the words.

CPR  -  cardiopulmonary resuscitation

I - Hands-only:  We're going to have to think of synonyms to capture this because I don't know of an official term for it.

 hands-only OR compression-only OR chest compression OR compression OR Heart Massage


CPR  -  cardiopulmonary resuscitation

C - Hands plus breathing Breathing is a tougher term to match.  I think I'll see how my search turns out without this search term since it's the conventional method, but I should be ready to add it in to narrow my results.

rescue breathing OR mouth to mouth

O - Mortality:  If your outcomes terms are general, they may not as useful in the literature search.  They will still be useful in your evaluation of the studies.


Putting it together - a search statement from the above might look like this:

CPR AND (hands-only OR compression-only OR chest compression OR compression OR Heart Massage) AND mortality

Note that the above strategy is only using terms from the I, C, and O of PICO.  Depending on results, we might add the P back in.