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Ask A Question

PICO is a useful tool for asking focused clinical questions.

PICO table

Can also use PICOT where T = type of question (eg: therapy) or T = Type of study (RCT or Cohort)

PICO clarifies the question, determines search concepts and type of study that is most appropriate to answer the question type.

PICO Worksheet
A printable worksheet to help you ask focused clinical questions and structure search terms.

Types of Questions

  • Clinical findings: how to properly gather and interpret findings from the history and physical examination.
  • Etiology: how to identify causes for disease (including its iatrogenic forms).
  • 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.
  • 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 our patient’s likely clinical course over time and anticipate likely complications of the disorder.
  • Prevention: how to reduce the chance of disease by identifying and modifying risk factors and how to diagnose disease early by screening.
  • Experience and meaning: (for qualitative research) how to empathize with our patients’situations, appreciate the meaning they find in the experience and understand how this meaning influences their healing.
  • Self-improvement: how to keep up to date, improve my clinical and other skills and run a better, more efficient clinical practice
Type of Question Type of Study Design
Therapy RCT > Cohort > Case control > Case series
Diagnosis Prospective, blind comparison to a gold standard or Cross-sectional
Aetiology/Harm  Cohort > Case control > Case series
Prognosis Cohort > Case control > Case series
Prevention RCT > Cohort > Case control > Case series
Clinical exam Prospective, blind comparison to a gold standard
Cost Economic analysis


Types of study designs:

Study designs can be organised into a hierarchy. As you progress up the hierarchy from Case Reports/Case Series to Meta-analysis there are fewer studies but their methodology is stronger.

Hierarchy of evidence image

Key Resource

Find it Fast!: The Clinical Question

Evidence-Based Practice Information Resources Tutorial no.2

A short video looking at clinical questions and the types of studies used to answer these. 

Cushing/Whitney Medical Library
Yale University School of Medicine