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Evidence-Based Practice: Nursing: Ask=PICO

What is PICO?

To formulate a clinical question, use the PICO format.
PICO or PICOT stands for the following:

P Patient or Problem
I Intervention
C Comparison
O Outcome
T Time (optional)

Question Types

Different types of questions are answered best by different types of studies.
The following table will help you identify the best studies for your clinical question.

Question Type Best Type of Study
Treatment Systematic Review / RCT
Diagnosis Systematic Review / Cross-sectional
Etiology / Harm Systematic Review / Cohort / Case-control
Prognosis Systematic Review / Cohort


View definitions for these study types in the Glossary.

Levels of Evidence