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Michael S. Kramer, MD; Stanley H. Shapiro, PhD
McGill University Montreal

JAMA. 1985;253(17):2493.

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In Reply.—

We are in complete agreement with Dr Baughan's two points about the role of placebo effects in randomized trials. In our discussion of blinding and unblinding, however, we were concerned not with the etiology of placebo effects in general, but rather with the uncontrolled placebo effect that can arise when the subject or his physician becomes aware of (ie, is unblinded to) the treatment received. Placebos are used in clinical trials to control for placebo effects. If unblinding occurs, eg, through differential side effects of the active and placebo treatments, the placebo effect will no longer be adequately controlled.

Dr Baughan's suggestion about description of the results of placebocontrolled trials is a strategy we recommend for attempting to assess bias due to unblinding. However, we do not advocate this strategy for the primary analysis of the trial's results, which "should be based on a comparison of the groups . . . [Full Text PDF of this Article]

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