Two-stage group sequential designs for comparative clinical trials (Q1029502)

Summary: Group sequential designs are widely used in Phase II clinical trials, which are usually undertaken to evaluate the response probability of specific treatment regimens. In most randomized clinical trials with sequential patient entry, a fixed sample size design is unjustified on ethical grounds and sequential designs are often impractical. However group sequential designs are generally more practical and they provide much of the saving possible from sequential designs. Optimal restricted two-stage designs are the simplest form of group sequential designs. In this study, group sequential designs obtained by \(\alpha^*(t)\) functions characterized using the type-I error probability and optimal restricted two stage design have been compared for the cases that the group sizes are equal. Furthermore, their efficiency regarding fixed sample size designs has been calculated and the results have been discussed.