Zucker David M, Denne Jonathan
Department of Statistics, Hebrew University, Mount Scopus, Jerusalem, Israel.
Biometrics. 2002 Sep;58(3):548-59. doi: 10.1111/j.0006-341x.2002.00548.x.
Clinical trialists recently have shown interest in two-stage procedures for updating the sample-size calculation at an interim point in a trial. Because many clinical trials involve repeated measures designs, it is desirable to have available practical two-stage procedures for such designs. Shih and Gould (1995, Statistics in Medicine 14, 2239-2248) discuss sample-size redetermination for repeated measures studies but under a highly simplified setup. We develop two-stage procedures under the general mixed linear model, allowing for dropouts and missed visits. We present a range of procedures and compare their Type I error and power by simulation. We find that, in general, the achieved power is brought considerably closer to the required level without inflating the Type I error rate. We also derive an inflation factor that ensures the power requirement is more closely met.
临床试验人员最近对两阶段程序表现出兴趣，即在试验的中间点更新样本量计算。由于许多临床试验涉及重复测量设计，因此希望有适用于此类设计的实用两阶段程序。Shih和Gould（1995年，《医学统计学》14卷，2239 - 2248页）讨论了重复测量研究的样本量重新确定，但处于高度简化的设定之下。我们在一般混合线性模型下开发两阶段程序，同时考虑到失访和未就诊情况。我们提出了一系列程序，并通过模拟比较它们的I型错误和检验效能。我们发现，一般来说，在不增加I型错误率的情况下，实际检验效能能更接近所需水平。我们还推导了一个膨胀因子，以确保更接近满足检验效能要求。
