Computations for group sequential boundaries using the Lan-DeMets spendingfunction method

We describe an interactive Fortran program which performs computations rela ted to the design and analysis of group sequential clinical trials using La n-DeMets spending functions. Many clinical trials include interim analyses of accumulating data and rely on group sequential methods to avoid conseque nt inflation of the type I error rate. The computations are appropriate for interim test statistics whose distribution or limiting distribution is mul tivariate normal with independent increments. Recent theoretical results in dicate that virtually any design likely to be used in a clinical trial will fall, into this category. Interim analyses need not be equally spaced, and their number need not be specified in advance. In addition to determining sequential boundaries using an alpha spending function, the program can per form power computations, compute probabilities associated with a given set of boundaries, and generate confidence intervals. Control Clin Trials 2000; 21:190-207 (C) Elsevier Science Inc. 2000.