title: Evidence-based medicine, heterogeneity of treatment effects, and the trouble with averages.
abstract: Evidence-based medicine is the application of scientific evidence to clinical practice. This article discusses the difficulties of applying global evidence ("average effects" measured as population means) to local problems (individual patients or groups who might depart from the population average). It argues that the benefit or harm of most treatments in clinical trials can be misleading and fail to reveal the potentially complex mixture of substantial benefits for some, little benefit for many, and harm for a few. Heterogeneity of treatment effects reflects patient diversity in risk of disease, responsiveness to treatment, vulnerability to adverse effects, and utility for different outcomes. Recognizing these factors, researchers can design studies that better characterize who will benefit from medical treatments, and clinicians and policymakers can make better use of the results.
authors.affiliation: University of California, Davis, CA, USA. rlkravitz@ucdavis.edu
authors.forename: Richard L
authors.initials: RL
authors.lastname: Kravitz
authors.forename: Naihua
authors.initials: N
authors.lastname: Duan
authors.forename: Joel
authors.initials: J
authors.lastname: Braslow
mesh_terms: D017277:Drug Approval / Q000331:legislation & jurisprudence; D019317:Evidence-Based Medicine; D006801:Humans; D011050:Policy Making; D010818:Practice Patterns, Physicians'; D016032:Randomized Controlled Trials as Topic; D016896:Treatment Outcome; D014481:United States; D014486:United States Food and Drug Administration