Considerations for Evaluating Treatment Effects From Randomized Clinical Trials

Abstract

This article focuses on the choice of treatment effect measures in randomized clinical trials (RCTs). Traditionally, an intention-to-treat (ITT) analysis is conducted with an implicit understanding that a treatment-policy effect is of greatest interest. In this article we contend that this approach may not always provide accurate information about clinically meaningful treatment effects, and we present an argument that for any RCT it is desirable to require an explicit definition of what treatment effect is of primary interest, known as the "estimand." We will discuss the limitations of the traditional ITT effect measures as well as the state-of-the art thinking with regard to estimands. Furthermore, we will offer alternate choices that acknowledge that treatments have multiple effects.