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Group-sequential logrank methods for trial designs using bivariate non-competing event-time outcomes
Tomoyuki Sugimoto1, Toshimitsu Hamasaki2, Scott R Evans3
1Graduate School of Data Science, Shiga University, 1-1-1 Banba, Hikone, Shiga, 522-8522, Japan. tomoyuki-sugimoto@biwako.shiga-u.ac.jp.
Abstract:
We discuss the multivariate (2L-variate) correlation structure and the asymptotic distribution for the group-sequential weighted logrank statistics formulated when monitoring two correlated event-time outcomes in clinical trials. The asymptotic distribution and the variance-covariance for the 2L-variate weighted logrank statistic are derived as available in various group-sequential trial designs. These methods are used to determine a group-sequential testing procedure based on calendar times or information fractions. We apply the theoretical results to a group-sequential method for monitoring a clinical trial with early stopping for efficacy when the trial is designed to evaluate the joint effect on two correlated event-time outcomes. We illustrate the method with application to a clinical trial and describe how to calculate the required sample sizes and numbers of events.
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