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Evidence Based Medicine: EBM Home

Resources for evidence based medicine.

Evidence-Based Information Strives for the Best in Care




Dr. David Sackett, Professor Emeritus, Clinical Epidemiology & Biostatistics at McMaster University defined evidence-based medicine as "the conscientious, explicit and judicious use of current best evidence in making decisions about the care or individual patients. The practice of EBM means integrating individual clinical expertise with the best available clinical evidence from systematic research."

Sackett DL, Straus SE, Richardson WS, Rosenberg W, Haynes RB. Evidence-Based Medicine: How to Practice and Teach EBM. London: Churchill Livingstone; 1997


There are five elements to consider when developing a good clinical research question:


Patient or Population Intervention Comparison Outcome Type of Study
Who should be included in the review?

What is the main intervention or treatment to assess the patient or population?

  Are there are other treatments or interventions to compare? What are the clincial outcomes? The best study/design methodology
Sample from the Centre for Evidence Based Medicine; University of Oxford,
  Patient or Problem Intervention
(a cause, prognostic factor, treatment, etc.)
Comparison Intervention
(if necessary)
Tips for Building Starting with your patient, ask “How would I describe a group of patients similar to mine?”
Balance precision with brevity.
Ask “Which main intervention am I considering?”Be specific. Ask “What is the main alternative to compare with the intervention?”Again, be specific. Ask “What can I hope to accomplish?” or “What could this exposure really affect?”Again, be specific.
Example “In patients with heart failure from dilated cardiomyopathy who are in sinus rhythm …” “… would adding anticoagulation with warfarin to standard heart failure therapy …” “… when compared with standard therapy alone …” “… lead to lower mortality or morbidity from thromboembolism. Is this enough to be worth the increased risk of bleeding?”


Type of Question Type of Study Methodology
Therapy : information needed about treatments (effectiveness, cost, etc.)

Double-Blind Randomized Controlled Trial

Diagnosis : information needed about a diagnostic test (sensitivity, accuracy, etc.) Controlled Trial
Prognosis : information needed about the course of the disease over time, expected complications, etc.

Cohort Studies

Case Control

Case Series

Etiology / Harm : information needed about causes of disease or contributing factors of disease Cohort Studies
Prevention : information needed about the prevention of disease (immunization, social factors, etc.)

Randomized Controlled Trial

Cohort Studies

Quality Improvement : information needed about clients' and health professionals' experiences and concerns Randomized Controlled Trial