A review and re-interpretation of a group-sequential approach to sample size re-estimation in two-stage trials.
Bottom Line: In this paper, we review the adaptive design methodology of Li et al. (Biostatistics 3:277-287) for two-stage trials with mid-trial sample size adjustment.We argue that it is closer in principle to a group sequential design, in spite of its obvious adaptive element.Several extensions are proposed that aim to make it even more attractive and transparent alternative to a standard (fixed sample size) trial for funding bodies to consider.
Affiliation: MRC Biostatistics Unit, Cambridge, UK.Show MeSH
Mentions: Figure 1 plots the total number of patients needed as a function of under design 1. We see that at the interim, if , then only 125 patients per arm are required for the trial in total. The dotted line in Figure 1 shows the distribution of the estimate when δ = 0.35 to indicate the proportion of times the study would stop early for efficacy or futility at stage one, or continue to stage two with the specified sample size.