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Evidence-Based Practice: PICO

Focusing Clinical Questions

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.


How would you describe a group of patients similar to yours? What are the most important characteristics of the patient?

What main intervention, exposure, or prognostic factor are you considering? What do you want to do with this patient?

What is the main alternative being considered, if any?

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

Types of Questions

Primary Question Types

  • Therapy: how to select treatments to offer our patients that do more good than harm and that are worth the efforts and costs of using them.
  • Diagnostic tests: how to select and interpret diagnostic tests, in order to confirm or exclude a diagnosis, based on considering their precision, accuracy, acceptability, expense, safety, etc.
  • Prognosis: how to estimate a patient's likely clinical course over time due to factors other than interventions
  • Harm / Etiology: how to identify causes for disease (including its iatrogenic forms).

Other Question Types

  • Clinical findings: how to properly gather and interpret findings from the history and physical examination.
  • Clinical manifestations of disease: knowing how often and when a disease causes its clinical manifestations and how to use this knowledge in classifying our patients' illnesses.
  • Differential diagnosis: when considering the possible causes of our patient’s clinical problem, how to select those that are likely, serious and responsive to treatment.
  • Prevention: how to reduce the chance of disease by identifying and modifying risk factors and how to diagnose disease early by screening.
  • Qualitative: how to empathize with our patients’ situations, appreciate the meaning they find in the experience and >understand how this meaning influences their healing.

From: Sackett, DL. Evidence-based medicine: how to practice and teach EBM.

Clinical Question + Study Design

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.