The Cytel blog keeps you up to speed with the latest developments in biostatistics and clinical biometrics.

Unblinded Sample Size Re-Estimation in Bioequivalence Trials with Small Samples

August 26, 2016

 

At the recent JSM in Chicago, Cytel’s Sam Hsaio and Lingyun Liu alongside Genentech's Romeo Maciuca, presented a framework for inference in adaptive bioequivalence trials with unblinded sample size re-estimation.

 

The Problem

In bioequivalence trials where the variance is often unknown, and the sample size small, using boundaries derived under the assumption of a normally distributed test statistic may lead to type I error inflation. This problem can be overcome with p-value combination methods, however these approaches generally do not directly provide confidence intervals for the geometric mean ratio on the scale of the original pharmacokinetic endpoint.

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