Chapter 34
Global Assessment Variables
34.1 Introduction
Although most clinical trials are designed using a single primary outcome, in some trials it is difficult to find the single most appropriate outcome for the main objective of the study. In the NINDS Stroke Trial, a consistent and persuasive post-stroke improvement on multiple outcomes was required to define treatment efficacy [1]. In Parkinson’s disease clinical trials, a treatment would not be considered to slow progression if the treatment improved only motor score and other measures of outcome deteriorated. In studying quality of life, we may be interested in treatment effects on all subscales being measured. In all cases, no single measure is sufficient to describe the treatment effect of interest, and no validated summary score exists. In a quality-of-life example, we could measure an overall quality-of-life score by summing across subscales, but we may under or overestimate the effect of treatment depending on how the treatment affects the individual subscales.
34.2 Scientific Questions for Multiple Outcomes
The choice of statistical method used for assessing treatment effect on multiple outcomes depends on the scientific question under investigation. Two types of questions lead to two different classes of tests. The first type is a directionless question: “Is there any difference, helpful or harmful between the two treatments in these outcomes?” A treatment difference ...
Get Methods and Applications of Statistics in Clinical Trials, Volume 1: Concepts, Principles, Trials, and Designs now with the O’Reilly learning platform.
O’Reilly members experience books, live events, courses curated by job role, and more from O’Reilly and nearly 200 top publishers.