A RANDOMIZED PLAY-THE-WINNER DESIGN FOR MULTIARM CLINICAL-TRIALS

A randomized adaptive allocation scheme is a design in which the probability a treatment is administered to each patient depends upon the results of the previous patients in the study. Typically, an arm that is doing well is more likely to be allocated to future patients than an arm that is doing poorly. Occasionally, ethical and/or practical considerations suggest that such designs may be appropriate. However, many issues need to be addressed in order to run the trial properly. Among these are studies with more than two arms, the logistics behind the trial, delayed patient response, and inferences drawn from data collected in this manner. This paper demonstrates ways these issues can be resolved, and presents some modifications to the current literature. A simulation study demonstrates the operating characteristics of the design.