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Study explores the ethics of using cluster randomized trials to compare drug effectiveness

Research Activities, May 2009, No. 345

Randomized controlled trials typically evaluate a drug's effectiveness compared to a placebo. Cluster randomized trials (CRTs), in which groups of patients are randomly assigned to different drugs, could provide a powerful way to compare different drugs to treat the same condition. However, CRTs have not been widely used, in large measure due to concerns about whether patients must give individual informed consent to participate in them. A new study concludes that CRTs of comparative drug effectiveness can ethically be conducted at health plans without requiring individual informed consent.

Researchers reached this conclusion after a review of the research ethics literature, consultation with a health plan ethics committee, interviews with patients, physicians, and health plan leaders, and their own ethical deliberations. They envision that physicians participating in the CRT would provide either drug A or drug B for a particular condition such as hypertension, which are both considered effective for that condition. Neither drug is considered "better" than the other (clinical equipoise).

Several health plans will participate with some favoring A and others favoring B. "Favor" means that unless clinicians have specific reasons for choosing the nonpreferred agent, they will use the preferred one. Health plan databases will be used to follow patterns of side effects, medication changes, and clinical outcomes.

Since the choice of drug A or B mimics clinical practice pretty closely, and the drugs are both effective, there is no need to get patient's consent in any way that differs from ordinary practice, note the researchers. However, there is a need to show respect for patients by treating them as research partners and explaining the existence of the CRT and rationale for conducting it.

The study was supported by the Agency for Healthcare Research and Quality (HS10391) to the HMO Research Network Center for Education and Research in Therapeutics (CERT). For more information on the CERTs program, please visit

More details are in "Comparing drug effectiveness at health plans: The ethics of cluster randomized trials," by James E. Sabin, M.D., Kathleen Mazor, Ed.D., Vanessa Meterko, and others, in the September-October 2008 Hastings Center Report 35 (5), pp. 39-48.

Current as of May 2009
Internet Citation: Study explores the ethics of using cluster randomized trials to compare drug effectiveness: Research Activities, May 2009, No. 345. May 2009. Agency for Healthcare Research and Quality, Rockville, MD.