Updated: Integrating internal and external evidence (created 2006-03-17, revised 2009-10-21).

Evidence based medicine involves the combining of the best available evidence with your clinical knowledge and the patient's individual values. A good article that emphasizes how this should be done is on the web at:

This article lists the following six steps (excerpted largely intact but with a few minor editting changes):

  1. Transformation of the clinical problem into 3 or 4 part question (relevant patient characteristics and problem(s), leading intervention, alternative intervention, and clinical outcomes or goals.)
  2. Answer to the question based on "internal evidence" only (acquired knowledge through professional training and experience in general and applied to the patient).
  3. Finding "external evidence" to answer the question (obtained from textbooks, journals, databases, experts).
  4. Critical appraisal of the external evidence (are the results valid? are the results clinically important? do the results apply to my patient?)
  5. Integrating external and internal evidence (how the decision is made when the two sources are non-supportive or conflicting will depend on multiple factors.)
  6. Evaluation of decision making process (once the decision has been made, the process and the outcome are considered and opportunities for improvement are identified).

The unique contribution of this article is the emphasis on integrating internal and external evidence. The authors note that many times, physicians will rebel against searching for evidence because it seems to deny the value of the training that they received. By explicitly asking for internal evidence, the modified process shows greater respect for clinical judgment. Because this process respects individual clinical expertise, it is actually more consistent with David Sackett's definition:

Evidence based medicine is 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. Evidence based medicine: what it is and what it isn't. D. L. Sackett, W. M. Rosenberg, J. A. Gray, R. B. Haynes, W. S. Richardson. Bmj 1996: 312(7023); 71-2. [Medline] [Full text]

This page was written by Steve Simon while working at Children's Mercy Hospital. Although I do not hold the copyright for this material, I am reproducing it here as a service, as it is no longer available on the Children's Mercy Hospital website. Need more information? I have a page with general help resources. You can also browse for pages similar to this one at Category: Critical appraisal.