Medical Hypotheses
Volume 59, Issue 3 , Pages 227-232, September 2002

In randomized controlled trials, should subjects in both placebo and drug groups be expected to guess that they are taking drug 50% of the time?

  • N.A Desbiens

      Affiliations

    • Corresponding Author InformationCorrespondence to: Norman A. Desbiens MD, Department of Medicine, University of Tennessee College of Medicine–Chattanooga Unit, 975 East Third Street, Box 94, Chattanooga, Tennessee 37403, USA. Phone: 423-778-2998; Fax: 423-778-2611

Department of Medicine, University of Tennessee College of Medicine–Chattanooga Unit, Tennesse, USA

Received 13 August 2001; accepted 19 December 2001.

Abstract 

Part of the design of some randomized controlled trials has included asking patients to guess whether they are taking placebo or active drug. Some authors have stated that in randomized, double-blind placebo-controlled clinical trials patients in each group should guess that they are taking placebo half the time. However, this pattern should occur only under a limited set of circumstances. This paper explores the factors that affect the guess and the role of the guess in understanding both the establishment and the maintenance of the blind. It suggests that more than half of those in the treatment group should guess they are taking active drug if treatment or side-effects are powerful. Though the randomized controlled trial has become the paradigmatic tool to assess treatment efficacy, studies are still needed to validate key assumptions make by investigators and the effect of violation of these assumptions on study outcomes.

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PII: S0306-9877(02)00205-0

Medical Hypotheses
Volume 59, Issue 3 , Pages 227-232, September 2002