Planning and analysis of repeated measures at key time-points in clinical trials sponsored by pharmaceutical companies

In this paper we explore the possible reasons why medical papers reporting clinical trials sponsored by the pharmaceutical industry often analyse repe ated measures data at certain key time-points instead of employing sophisti cated models of repeated measures proposed by many statisticians. A survey indicated that the priority reason in the industry for having repeated meas ures in clinical trials is to monitor the trial and to utilize the early re sults for strategic decision making. We discuss what the common statistical methods do and do not offer for analysis of repeated measures in such clin ical trials. We advocate the need to improve the understanding of the medic al interest in conducting longitudinal trials in the industry, and to plan and analyse the repeated measures accordingly. We address the medical inter est by formulating the problem and give illustrative examples for both phas es II and III trials. Copyright (C) 1999 John Wiley & Sons, Ltd.