University of Wisconsin, Madison, USA.
Comput Methods Programs Biomed. 2012 Oct;108(1):197-202. doi: 10.1016/j.cmpb.2012.03.013. Epub 2012 May 18.
The biased coin randomization approach is frequently adopted in randomized clinical trials to control the balance in overall treatment assignments. In this article, an algorithm is developed to theoretically determine the exact allocation ratios for all the patients that will be enrolled in a randomized clinical trial with biased coin randomization based on the order in which they are randomized. Our results show that the exact allocation ratios can significantly deviate from the ratio as specified for the trial, which poses challenges to the enrollment of the trial and to the interpretation of the results. In order to maintain a constant allocation ratio throughout the trial, a modification of the widely adopted permuted block randomization is proposed, which is shown to achieve better balance for not only the overall treatment assignments but also the baseline stratification variables that are desired to be balanced at the end of the trial.
偏倚硬币随机化方法常用于随机临床试验中，以控制总体治疗分配的平衡。本文开发了一种算法，根据随机化的顺序，从理论上确定将被纳入偏倚硬币随机化的随机临床试验的所有患者的确切分配比例。我们的结果表明，确切的分配比例可能会显著偏离试验指定的比例，这对试验的招募和结果的解释构成了挑战。为了在整个试验中保持恒定的分配比例，提出了对广泛采用的区组随机化的修改，结果表明，该方法不仅对总体治疗分配，而且对希望在试验结束时平衡的基线分层变量都能达到更好的平衡。
