Berger Vance W, Ivanova Anastasia, Knoll Maria Deloria
National Cancer Institute, EPN, Suite 3131, 6130 Executive Boulevard, MSC-7354, Bethesda, MD 20892-7354, USA.
Stat Med. 2003 Oct 15;22(19):3017-28. doi: 10.1002/sim.1538.
The interpretation of between-group comparisons is facilitated by the creation of treatment groups that are similar to each other in baseline composition. To prevent treatment effects from being confounded with time effects, most trials use restricted randomization to force balance. An unintended consequence of these restrictions is that they create patterns that allow for the prediction of future treatment allocations, and hence selection bias, especially in unmasked trials. In fact, the more restrictive the allocation procedure, the greater the potential for selection bias. It was decided, in the context of a recent clinical trial comparing two dosing schedules of paclitaxel and carboplatin for advanced stage IIIB/IV non-small-cell lung cancer, that the randomized block procedure could not simultaneously protect sufficiently against both selection and chronological bias. In this paper we detail our development of the maximal procedure. The maximal procedure takes as input the extent of chronological bias allowed by the randomized block procedure, then matches it, but does so with fewer restrictions. This feature makes the maximal procedure more resistant to selection bias than the randomized block procedure is.
通过创建在基线组成上彼此相似的治疗组，有助于组间比较的解释。为防止治疗效果与时间效应混淆，大多数试验使用受限随机化来强制实现平衡。这些限制的一个意外后果是，它们会产生一些模式，使得未来的治疗分配能够被预测，从而导致选择偏倚，尤其是在开放试验中。事实上，分配程序的限制越多，选择偏倚的可能性就越大。在最近一项比较紫杉醇和卡铂两种给药方案用于晚期IIIB/IV期非小细胞肺癌的临床试验中，发现随机区组程序无法同时充分防范选择偏倚和时间顺序偏倚。在本文中，我们详细介绍了最大程序的开发过程。最大程序将随机区组程序允许的时间顺序偏倚程度作为输入，然后进行匹配，但限制较少。这一特性使得最大程序比随机区组程序更能抵抗选择偏倚。
