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NUR 354: Evidence-Based Nursing

PICO Resource Center

Using PICO to Formulate Clinical Questions

PICO (alternately known as PICOT) is a mnemonic used to describe the four elements of a good clinical question. It stands for:


Many people find that it helps them clarify their question, which in turn makes it easier to find an answer. 

Use PICO to generate terms - these you'll use in your literature search for the current best evidence. Once you have your PICO terms, you can then use them to re-write your question. (Note: you can do this in reverse order if that works for you.)


Often we start with a vague question such as, "How effective is CPR, really?"  But, what do we mean by CPR?  And how do we define effective?  PICO is a technique to help us - or force us - to answer these questions.   Note that you may not end up with a description for each element of PICO. 

P -  our question above doesn't address a specific problem other than the assumption of a person who is not breathing. So, ask yourself questions such as, am I interested in a specific age cohort? (Adults, children, aged); a specific population (hospitalized, community dwelling); 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 the standard, hands plus breathing

O - Again, we need to ask, what do we mean by 'effective'?  Mortality is one option with the benefit that it's easily measured. 

Our PICO statement would look like:

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

From our PICO, we can write up a clearer and more specific question, such as:

"In community dwelling adults, how effective is hands-only CPR versus hands plus breathing CPR at preventing mortality?"

Now that we've clarified what we want to know, it will be much easier to find an answer.

More on PICO & Clinical questions

We can use our PICO statement to list terms to search on.  Under each letter, we'll list all the possible terms we might use in our 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: I would use the limits in MEDLINE or CINAHL for All Adults.  Could also consider the following depending upon the population you need:

adult OR adults OR aged OR elderly OR young adult


CPR  -  cardiopulmonary resuscitation

I - Hands-only

 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.

breathing OR mouth to mouth OR conventional OR traditional

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.

mortality OR death OR Survival

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

cardiopulmonary resuscitation AND (hands-only OR compression-only OR chest compression OR compression OR Heart Massage) AND (breathing OR mouth to mouth OR conventional OR traditional)

Note that the above strategy is only using terms from the I and the C of PICO.  Depending upon the results, you may need to narrow your search by adding in terms from the P or the O.