Intended for healthcare professionals


Composite and surrogate outcomes in randomised controlled trials

BMJ 2007; 334 doi: (Published 12 April 2007) Cite this as: BMJ 2007;334:756
  1. Nick Freemantle, professor of clinical epidemiology and biostatistics,
  2. Mel Calvert, research fellow
  1. Health Care Evaluation Group, University of Birmingham, Birmingham B15 2TT
  1. N.Freemantle{at}

    Composite end points may mislead—and regulators allow it to happen

    In this week's BMJ, Ferreira-González and colleagues report that clinical trials may mislead if they use composite end points.1 For example, a statement that an intervention reduces a composite end point of cardiovascular mortality, myocardial infarction, and revascularisation procedures is misleading if revascularisation procedures were more common outcomes than death or infarction, or if the intervention had a large apparent treatment effect on revascularisation but not on death or infarction.1 It is not enough for people who use the research—doctors and patients—to be aware of such potential to mislead: pharmaceutical regulators should also examine their role.

    Pharmaceutical regulation has provided benefit to society by harnessing the innovation of industry towards improving health. Pharmaceutical regulation helps to ensure that drugs are safe and achieve clinically relevant benefits for patients. Regulation also governs the manner in which drugs may be marketed to prescribers and to patients. It allows only claims that can be supported by trial evidence to be used as a basis for promotional activities. Ensuring the evidence base of information to prescribers is a laudable aim, but as Alfred North Whitehead said, “We think in generalities, but we live in detail.” The implementation of regulation has led to innovation in trial design, …

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