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.
PICO or PICOTT:
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, PROGNOSTIC FACTOR
What main intervention, exposure, or prognostic factor are you considering? 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?
Type of Question
Therapy / Diagnosis / Harm / Prognosis / Prevention
Type of Study
Systematic review / RCT / cohort study / case-control
Primary Question Types
Other Question Types
From: Sackett, DL. Evidence-based medicine: how to practice and teach EBM.
The type of question will often dictate the best study design to address the question. In the absence of the best study design, move down the hierarchy of evidence:
Clinical Question Type | Study Design |
---|---|
Clinical Examination | Prospective, blind comparison to gold / reference standard |
Diagnostic Testing or Screening | Prospective, blind comparison to gold / reference standard |
Prognosis | Cohort Study > Case Control Study > Case Series |
Therapy | Randomized Controlled Trial (RCT) |
Prevention | RCT > Cohort Study > Case Control Study > Case Series |
Etiology / Harm | RCT* > Cohort Study > Case Control Study > Case Series |
Cost | Economic analysis |
*it is not always ethical to randomize people to a known harmful exposure. However, some RCTs do contain information on adverse events, side effects, etc. that could be helpful in answering certain clinical questions regarding harms.