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July 4, 2007

Eligibility Criteria of Randomized Controlled Trials—Reply

Author Affiliations

Letters Section Editor: Robert M. Golub, MD, Senior Editor.

JAMA. 2007;298(1):39-40. doi:10.1001/jama.298.1.39-b

In Reply: In response to Dr Costantino and colleagues, we did examine associations between the total number of exclusion criteria and outcome of RCTs. We found substantial variability in the reporting of an RCT as “positive” or “negative.” Occasionally, the study hypothesis and a priori-designated primary outcome were not clearly stated. Among 258 RCTs with a clearly identified and reported hypothesis and primary outcome, 185 (71.7%) had a positive outcome and 73 (28. 3%) had a negative primary outcome. This asymmetry in rate of publication of positive and negative trials has been shown by others.13 However, we found no difference between the number of exclusion criteria of “positive” vs “negative” RCTs (mean [SD], 9.6 [6.3] vs 9.7 [6.0], respectively; P = .97).

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