Interim evaluation of efficacy or futility in group-sequential trials with two time-to-event outcomes
Primary: Toshimitsu Hamasaki Author(s): Toshimitsu . Hamasaki Koko Asakura Scott R. Evans Tomoyuki Sugimoto Chin-Fu Hsiao Haruko Yamamoto National Cerebral and Cardiovascular Center National Cerebral and Cardiovascular Center Harvard T.H.Chan School of Public Health Kagoshima University National Health Research Institutes National Cerebral and Cardiovascular Center
SCT Annual Meeting 2018
We discuss logrank test-based methods for efficacy or futility evaluation in group-sequential clinical trials that compare two interventions with respect to two time-to-event outcomes. Evaluation is conducted under three situations: (a) both events are non-composite and non-fatal, (b) both events are non-composite, but one event is fatal, and (c) one event is composite, but other is fatal and non-composite. Based on group-sequential boundaries, we consider several decision-making frameworks for evaluating efficacy or futility. We consider two inferential goals, evaluating if a test intervention is superior to a control intervention on: (i) both outcomes (Co-primary endpoints: CPE), and (ii) at least one outcome (multiple primary endpoints: MPE). For the CPE goal, we incorporate the correlations among the outcomes into the calculations for non-binding futility boundaries and sample sizes (or event numbers) as a function of other design parameters, including mean differences, the number of analyses, and efficacy boundaries. We investigate the operating characteristics of the decision-making frameworks in terms of efficacy/futility boundaries, power, the Type I error rate, sample sizes, event numbers, while varying the number of analyses, the correlations among the outcomes, and hazard ratios. We provide examples to illustrate the methods and discuss practical considerations when designing group-sequential designs in clinical trials with two time-to-event outcomes.