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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

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