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Updated: Jul 16, 2026

A Clinical Trial Assessing the Safety, Efficacy, and Delivery of Olive-Oil-Based Three-Chamber Bags for Parenteral Nutrition
Published on: September 20, 2019
Release of data from an ongoing randomized clinical trial for sample size adjustment or planning
Boris Freidlin1, Edward L Korn
1Biometric Research Branch, EPN-8122, National Cancer Institute, Bethesda, MD 20892-7434, USA. freidlinb@ctep.nci.nih.gov
Abstract:
The determination of an appropriate sample size is a key issue in planning and designing randomized clinical trials. In settings with time-to-event or binary outcomes, the required sample size depends on the control-arm event (response) rate. An accurate estimate of this rate is not often available at the planning stage. Therefore, non-comparative control-arm or pooled-arm event rates from an ongoing trial are sometimes released for sample size adjustment or planning purposes. It is shown that such non-comparative data release may still contain information on the relative treatment benefit and may thus adversely affect the ongoing trial. A simple approach to minimizing the effect of the data release is suggested.
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