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Featured Clinical Reviews

The Medical Literature
October 13, 1999

Users' Guides to the Medical Literature: XIX. Applying Clinical Trial Results
B. Guidelines for Determining Whether a Drug Is Exerting (More Than) a Class Effect

Author Affiliations

Author Affiliations: National Health Service Research and Development Centre for Evidence-Based Medicine, John Radcliffe Hospital, Oxford, England (Drs McAlister and Sackett); Division of General Internal Medicine, Ottawa Hospital (Dr Laupacis), and Clinical Epidemiology Unit, Loeb Health Research Institute (Drs Laupacis and Wells), Ottawa, Ontario.


Users' Guides to the Medical Literature Section Editor: Drummond Rennie, MD, Deputy Editor (West), JAMA.

JAMA. 1999;282(14):1371-1377. doi:10.1001/jama.282.14.1371

Most classes of drugs include multiple compounds. The opinions of clinicians, manufacturers, and purchasers may differ as to whether a particular drug is more efficacious, safer, or more cost-effective than others in its class.1 In this article, we review the types of evidence commonly cited to support the prescribing of a particular drug rather than another of the same class and provide a hierarchy for grading studies that compare a drug with another of the same class, expanding on our discussion in part A of this Users' Guide.2

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