Evidence-based medicine (EBM) is defined as "the conscientious, explicit and judicious use of current best evidence in making decisions about the care of individual patients.The practice of evidence based medicine means integrating individual clinical expertise with the best available external clinical evidence from systematic research."
Source: Sackett DL, Rosenberg WM, Gray JA, Haynes RB, Richardson WS (January 1996). "Evidence based medicine: what it is and what it isn't". BMJ 312 (7023): 71–2.
The five A's of the evidence-based medicine process
1. Assess
Identify the clinical problem. What is it you want to know?
2. Ask
Use the PICO formula to create a good question:
P=PATIENT – Who is your patient?
I=INTERVENTION – Are you looking to diagnose? Treat? Learn about a prognosis?
C=COMPARISON – Is there a control? Placebo? A "gold standard"?
O=OUTCOME – What do you hope to accomplish? Better/best treatment? Decreased mortality?
3. Acquire
Use your PICO formula to search for good evidence. Start your search using only two to three terms - you can always add more.
4. Appraise
What have you found? Where did you find it? Are the results significant to your patient? How strong is the evidence? Are there any confounding variables such as bias present?
5. Apply
Now apply and discuss the evidence you have found with your patient.
Evidence-Based Medicine: How to practice and teach EBM by 
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