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EBM: EBM/Critical Appraisal

Evidence Based Medicine and Critical Appraisal tools and learning resources

Tutorials & Outside Links

The Cochrane Library

What is Evidence-Based Medicine?

"Evidence-based medicine is the conscientious explicit and judicious use of current best evidence in making decisions about the care of individual patients"

The concepts underlying EBM (also called EBP at times) is making sure that when decisions are made, they are made on the basis of the most up-to-date, solid, reliable, scientific evidence. These are the decisions about the care of individual patients. 

Key Components:

  1. Asking the right question

  2. Searching for the evidence

  3. Appraising the evidence

  4. Applying the evidence (using input from patient, too!)


EBM Process

The 5 A's

  1. Assess - Assess the patient or problem to determine the pertinent issues
  2. Ask - Ask a clear, answerable question to be pursued
  3. Acquire - Acquire the evidence from an appropriate source
  4. Appraise - Appraise the evidence to further examine its worth and reliability
  5. Apply - Apply the evidence to the particular patient and their unique values

Forming a Clinical Question

General Question:

General questions or background questions ask for basic knowledge about an illness, disease, condition, test, process or thing. These types of questions typically ask who, what, where, when, how & why about things like a disorder, test, or treatment, etc.

For example

  • What is hairy cell leukemia?
  • What are the adverse effects of Black Cohosh?
  • What is the mechanism of action for dopamine agonists?
  • What causes seizures?
  • What are the diagnostic criteria for Deep Vein Thrombosis?

These types of questions are best answered by medical textbooks, point-of-care tools (e.g. DynaMed Plus, Essential Evidence Plus, Lexicomp, OvidMD), and narrative review articles.

Focusing a Question:

A well-built clinical foreground question should have at least 4 components. The PICO model is a helpful tool that assists you in organizing and focusing your foreground question into a searchable query.

P = Patient, Problem, Population (How would you describe a group of patients similar to you? What are the most important characteristics of the patient?)

I = Intervention, Prognostic Factor, Test, Exposure (What main intervention are you considering? What do you want to do with this patient? What is the main alternative being considered?)

C = Comparison (What is the main alternative to compare with the intervention? Are you trying to decide between two drugs, a drug and no medication,  placebo, or standard of care, or two diagnostic tests?)

O= Outcome (What are you trying to accomplish, measure, improve or affect? Outcomes may be disease-oriented or patient-oriented.)

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Clinical Librarians

Michele Mason-Coles, MLS

Darnall Medical Library
Building 1, Room 3458


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