The Effects of Treatment Noncompliance on Power in a 2x2 Factorial Design

Publication Type
Journal Article
Year of Publication
1996
Authors
Lindblad, AS
Secondary
J Biopharm Stat
Volume
6
Start Page
263
Pagination
263-270
Date Published
07/1996
Keywords
Data Interpretation- Statistical; Follow-Up Studies; Patient Compliance; Patient Dropouts; Placebos; Randomized Controlled Trials as Topic
Abstract
Clinical trials testing interventions that are available to the public and thus to potential participants must consider the impact of noncompliance on the power of the planned study to detect treatment differences. In long-term trials noncompliance may be assumed to vary over time. Increases in power of the F-test to detect differences in the proportion of participants responding to treatment in a 2 x 2 factorial design are observed when a simple, discrete, time-varying noncompliance model is compared to an assumption of immediate noncompliance. This increase holds in the presence of interaction and can become more substantial as trial duration lengthens or alpha level decreases.