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Ask a clear, answerable question.

The first critical step is to clarify one or two key issues that come up in the course of caring for your patient and to develop a focused clinical question.
Without this crucial step, the rest of the steps are immaterial.

A well-built clinical question has four components. The mnemonic PICO is useful for remembering these.
  • Patient or Population -- Be specific about the group you are interested in. Consider age, sex, risk profile, or other traits that may be clinically relevant.
  • Intervention -- Again, be specific about the intervention (or exposure) you are looking for (e.g., treatment with inhaled corticosteroids, passive smoking, surgical procedure)
  • Comparison Intervention -- What alternatives do you want to compare the intervention to (e.g., standard therapy for asthma, chest x-ray, watchful waiting)
  • Outcome -- Try to be precise, yet brief, in defining the outcome (e.g. growth delay, diagnostic usefulness)
In addition to the PICO model, there are a number of variations, one of which is PICOTT. This model reflects that the type of question you are asking will yield various study types.
  • T -- What type of question are you asking? Therapy/Treatment, Diagnosis, Prognosis, Harm/Etiology, Prevention, Quality Improvement.
  • T -- What type of study do you want to find? What would be the best study design/methodology?
Type of Question/Domain  Type of Study/Methodology

Selection of treatments or interventions that do more good than harm and that are worth the effort and cost.
Double-Blind Randomized Controlled Trial

Systematic Review/Meta Analysis

Selection and interpretation of diagnostic tests, in order to confirm or exclude a diagnosis, based on considering their precision, accuracy, acceptability, expense, safety, etc.
Randomized Controlled Trial

Systematic Review/Meta Analysis

Estimation of a patient's likely clinical course over time and anticipation of likely complications of disease.
Cohort Study

Case Controlled Study

Case Series

Identification of causes or risk factors for disease.
Cohort Studies
Randomized Controlled Trial

Cohort Studies
Quality Improvement Randomized Controlled Trials

In elderly patients, are ACE inhibitors more effective than beta blockers in controlling high blood pressure and minimizing adverse effects?

The “Population” is elderly patients, the “Intervention” is ACE inhibitors, the “Comparison Intervention” is beta blockers, and the “Outcome” is controlling high blood pressure and minimizing adverse effects.

In children with asthma, are inhaled steroids more likely to result in growth delay than standard therapy with beta-agonists

The “Population” is children with asthma, the “Intervention” is inhaled steroids, the “Comparison Intervention” is beta-agonists and the “Outcome” is growth delay.
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