The most common definition of evidence-based medicine (EBM) is taken from Dr. David Sackett. EBM is "the conscientious, explicit and judicious use of current best evidence in making decisions about the care of the individual patient. It means integrating individual clinical expertise with the best available external clinical evidence from systematic research." (Sackett D, 1996)
The video below provides additional information about EBM.
|
Level |
Type of evidence |
|
I |
High quality prospective cohort study with adequate power or systematic review of these studies |
|
II |
Lesser quality prospective cohort, retrospective cohort study, untreated controls from an RCT, or systematic review of these studies |
|
III |
Case-control study or systematic review of these studies |
|
IV |
Case series |
|
V |
Expert opinion; case report or clinical example; or evidence based on physiology, bench research or “first principles” |
“The levels of evidence are an important component of evidence-based medicine. Understanding the levels and why they are assigned to publications and abstracts helps the reader to prioritize information. This is not to say that all level 4 evidence should be ignored and all level 1 evidence accepted as fact. The levels of evidence provide a guide and the reader needs to be cautious when interpreting these results.” (Burns, 2011)
"Levels of Evidence" are often represented as a pyramid.
Image from: Evidence-Based Practice in the Health Sciences: Evidence-Based Nursing Tutorial
Information Services Department of the Library of the Health Sciences-Chicago, University of Illinois at Chicago.
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Burns, P. B., Rohrich, R. J., & Chung, K. C. (2011). The levels of evidence and their role in evidence-based medicine. Plastic and reconstructive surgery, 128(1), 305–310. https://doi.org/10.1097/PRS.0b013e318219c171
Sackett, D. L., Rosenberg, W. M., Gray, J. A., Haynes, R. B., & Richardson, W. S. (1996). Evidence based medicine: what it is and what it isn't. BMJ (Clinical research ed.), 312(7023), 71–72. https://doi.org/10.1136/bmj.312.7023.71
Coulter Library, Onondaga Community College, Syracuse, NY