How do multi-stage, multi-arm trials compare to the traditional two-arm parallel group design - a reanalysis of 4 trials

Background: To speed up the evaluation of new therapies, the multi-arm, multi-stage trial design was suggested previously by the authors. Methods: In this paper, we evaluate the performance of the two-stage, multi-arm design using four cancer trials conducted at the MRC CTU. The performance of the design at fictitious interim analyses is assessed using a conditional bootstrap approach. Results: Two main aims are addressed: the error rate of correctly carrying on/stopping the trial at an interim analysis as well as quantifying the gains in terms of resources by employing this design. Furthermore, we make suggestions for the best timing of this interim analysis. Conclusion: Multi-arm, multi-stage trials are an effective way of speeding up the therapy evaluation process. The design performs well in terms of the type I and II error rates.