POWER CONSIDERATIONS FOR CLINICAL-TRIALS USING MULTIVARIATE TIME-TO-EVENT DATA

Many clinical trials involve the collection of data on the times to oc currence of different types of events, such as different fungal infect ions in AIDS research, or of recurrences of the same type, such as suc cessive fits in epilepsy research. The multivariate proportional hazar ds model allows for analysis of this data and software for doing this is now widely available. In this paper, the approximate power of a cli nical trial that aims to use such data for comparing two treatments is derived. Special attention is given to the bivariate case, both to sh ow that the approximation works well and to illustrate how various des ign parameters affect the power of a trial. As with any multivariate d ata in clinical trials, there are many conceptual issues that should b e considered during trial design; the paper closes with a discussion o f some of these. (C) 1997 by John Wiley & Sons, Ltd. Stat. Med., Vol. 16, 865-882 (1997).