ABSTRACT
The fundamental problem with sequential randomization was described some time ago in a review of clinical trials in acquired immunodeficiency.2. The authors pointed out that such patients might often be enrolled on more than one trial in sequence and that this could confuse the interpretation of the initial trial. For example, if one of the therapies on the second trial proved extremely effective and more patients on one of the arms of the first reached an end point that made them eligible for the second, the apparent effectiveness of that arm might actually be due to the treatment studied in the second trial.
