The application of enhanced parallel gatekeeping strategies.

The parallel gatekeeping strategy proposed by Dmitrienko et al. (Statist. Med. 2003; 22:2387-2400) provides a flexible framework for the pursuit of strong control on study wise type I error rate. This paper further explores the application of the weighted Simes parallel gatekeeping procedure recommended by Dmitrienko et al. and proposes some modifications to it to better incorporate the interrelationships of different hypotheses in actual clinical trials and to achieve better power performance. We first propose a simple method to quantitatively control the impact of secondary tests on the testing of primary hypotheses. We then introduce a matched gatekeeping procedure to exemplify how to address special relationships between individual primary and secondary tests following the parallel gatekeeping framework. Our simulation study demonstrates that the enhanced gatekeeping procedures generally result in more powerful tests than the parallel gatekeeping procedure in Dmitrienko et al. whenever applicable. Copyright 2004 John Wiley & Sons, Ltd.