Methods and Applications of Statistics in Clinical Trials, Volume 2: Planning, Analysis, and Inferential Methods

Chapter 45

Secondary Efficacy End Points

Frank Rockhold and Tony Segreti

45.1 Introduction

As it will become clear later on in this article, there has not been a great deal of discussion concerning the handling and analysis of secondary efficacy end points in clinical trials, and, as a result, this article is timely in its content. Many of the statistical and design issues for secondary end points are similar to those seen for handling primary end points, but some important differences exist in interpretation and emphasis that are relevant to this discussion.

In clinical research settings (especially those involving interactions with regulatory agencies) that evaluate new drug and vaccine candidates, it is usually recommended that clinical trials have a single primary objective measured by a single primary variable, which typically includes hypothesis testing about comparative efficacy of the products under study. Secondary end points or other supportive measures are related to secondary objectives. Although many trials have more than one primary end point, a push to minimize the number of primary end points usually occurs. Clinical trials are large, complex, long, expensive, and, most importantly, rely on the commitment of the patients to participate in a study protocol. A need exists to balance the desire to maximize the amount of information collected in any given study with the amount of measurement that it is reasonable to expect a patient to endure. The amount of information ...