A parametric multiple test procedure to adaptive group-sequential trials allowing for mid-term modifications.

Adaptive group-sequential trials incorporating mid-term design modifications, such as selection of hypotheses or treatment groups, or sample size reestimation during the interim analysis, provide efficient tools to utilize the data from enrolled patients. A graphical multiple test procedure using weighted Bonferroni test has been proposed in adaptive group-sequential designs based on a marginal p-value combination approach. Multiple test procedures using weighted Bonferroni test may result in potential power loss when the test statistics are positively correlated. This paper proposes a graphical approach for adaptive group-sequential trials using weighted parametric test which utilizes the correlation structure between test statistics. The proposed parametric approach is more powerful than the Bonferroni-based approach and preserves the familywise Type I error. The proposed approach is appealing in adaptive designs with the option of treatment selection during the interim analysis and seamless combination of the dose finding and confirmatory stage, because it can utilize the natural correlations between the test statistics resulting from comparing a few treatment groups to a common control group. Simulations are conducted to evaluate the power and Type I error. The proposed parametric approach is illustrated with a confirmatory two-stage adaptive design with a dose selection stage and confirmatory stage with the selected treatment groups.