Collection of Biostatistics Research Archive

Title

Detailed Version: Analyzing Direct Effects in Randomized Trials with Secondary Interventions: An Application to HIV Prevention Trials

Authors

Michael A. Rosenblum, University of California, BerkeleyFollow
Nicholas P. Jewell, Division of Biostatistics, School of Public Health, University of California, BerkeleyFollow
Mark J. van der Laan, Division of Biostatistics, School of Public Health, University of California, BerkeleyFollow
Stephen Shiboski, Department of Epidemiology and Biostatistics, University of California, San FranciscoFollow
Ariane van der Straten, Women's Global Health Imperative, Department of Obstetrics, Gynecology, and Reproductive Services, University California, San FranciscoFollow
Nancy Padian, Women's Global Health Imperative, Department of Obstetrics, Gynecology, and Reproductive Services, University of California, San FranciscoFollow

Abstract

This is the detailed technical report that accompanies the paper “Analyzing Direct Effects in Randomized Trials with Secondary Interventions: An Application to HIV Prevention Trials” (an unpublished, technical report version of which is available online at http://www.bepress.com/ucbbiostat/paper223).

The version here gives full details of the models for the time-dependent analysis, and presents further results in the data analysis section. The Methods for Improving Reproductive Health in Africa (MIRA) trial is a recently completed randomized trial that investigated the effect of diaphragm and lubricant gel use in reducing HIV infection among susceptible women. 5,045 women were randomly assigned to either the active treatment arm or not. Additionally, all subjects in both arms received intensive condom counselling and provision, the "gold standard" HIV prevention barrier method.

There was much lower reported condom use in the intervention arm than in the control arm, making it difficult to answer important public health questions based solely on the intention-to-treat analysis.

We adapt an analysis technique from causal inference to estimate the "direct effects" of assignment to the diaphragm arm, adjusting for condom use in an appropriate sense.

Issues raised in the MIRA trial apply to other trials of HIV prevention methods, some of which are currently being conducted or designed.

Disciplines

Design of Experiments and Sample Surveys | Longitudinal Data Analysis and Time Series | Statistical Methodology | Statistical Theory

Suggested Citation

Rosenblum, Michael A.; Jewell, Nicholas P.; van der Laan, Mark J.; Shiboski, Stephen; van der Straten, Ariane; and Padian, Nancy, "Detailed Version: Analyzing Direct Effects in Randomized Trials with Secondary Interventions: An Application to HIV Prevention Trials" (October 2007). U.C. Berkeley Division of Biostatistics Working Paper Series. Working Paper 225.
https://biostats.bepress.com/ucbbiostat/paper225