This article has been motivated by an ongoing international adaptive confirmatory trial. At the interim analysis of this two-stage trial, none, one or two active treatment regimens are selected for further study in the second stage. A combination test approach is used in this practical setting with an extension of the theory to unbalanced randomization. We show that a combination test with suitable weights can still preserve the overall Type I error rate provided that the test statistic is chosen appropriately and the unpooled Z-test for proportions is not used. The accuracy of stagewise p-values is also discussed in a more general framework. Monte Carlo simulations confirm the validity of the approach retained and evaluate the necessary sample size. Additional issues addressed during the design of the trial are also examined such as multiplicity due to testing hypotheses on key secondary endpoints, a non-inferiority comparison to an active treatment and covariate adjusted analyses for various types of outcome.
AD - The George Institute, Sydney, Australia. AN - 21432887 BT - Statistics in Medicine ET - 2011/03/25 LA - eng M1 - 13 N1 - Heritier, StephaneLo, Serigne NMorgan, Caroline CResearch Support, Non-U.S. Gov'tEnglandStatistics in medicineStat Med. 2011 Jun 15;30(13):1541-54. doi: 10.1002/sim.4179. Epub 2011 Mar 22. N2 -This article has been motivated by an ongoing international adaptive confirmatory trial. At the interim analysis of this two-stage trial, none, one or two active treatment regimens are selected for further study in the second stage. A combination test approach is used in this practical setting with an extension of the theory to unbalanced randomization. We show that a combination test with suitable weights can still preserve the overall Type I error rate provided that the test statistic is chosen appropriately and the unpooled Z-test for proportions is not used. The accuracy of stagewise p-values is also discussed in a more general framework. Monte Carlo simulations confirm the validity of the approach retained and evaluate the necessary sample size. Additional issues addressed during the design of the trial are also examined such as multiplicity due to testing hypotheses on key secondary endpoints, a non-inferiority comparison to an active treatment and covariate adjusted analyses for various types of outcome.
PY - 2011 SN - 1097-0258 (Electronic)0277-6715 (Linking) SP - 1541 EP - 54 T2 - Statistics in Medicine TI - An adaptive confirmatory trial with interim treatment selection: practical experiences and unbalanced randomization VL - 30 ER -