Group sequential analyses for the mean function of a repeated measure process

In many clinical trials, treatment efficacy is based upon response to a bio logical marker that is measured repeatedly during the course of follow-up. However, in some of these trials it is not clear, a priori, how treatment e ffects on the marker may manifest themselves or what kinds of effects are c linically meaningful and/or acceptable. It is, therefore, desirable to allo w flexibility in design and monitoring process by not prespecifying a stopp ing rule or even the parameter on which inferences will be based. Using the more general results in Hu and Lagakos, this paper extends the idea of the repeated confidence intervals for a parameter (Jennison and Turnbull) to r epeated confidence bands for the mean function of a repeated measure proces s. We illustrate the approach and some considerations in its application wi th the results of a recent AIDS clinical trial. Copyright (C) 1999 John Wil ey & Sons, Ltd.