Discussion on “Second-Guessing Clinical Trial Designs” by Jonathan J. Shuster and Myron N. Chang

Abstract While one may impose the group sequential design of one's choice on a completed trial in order to “second-guess” if a trial could have stopped early for either efficacy or futility, such calculations do not consider the mind-set of either those conducting the trial or the data and safety monitoring committee that reviewed the accumulating data. It is thus easy to come to questionable conclusions because of incomplete information. The optimal four-stage designs are interesting, but would be more useful if unequal look times were incorporated and software were made available.