Open Access
August 2022 Intention-to-Treat Comparisons in Randomized Trials
Ross L. Prentice, Aaron K. Aragaki
Author Affiliations +
Statist. Sci. 37(3): 380-393 (August 2022). DOI: 10.1214/21-STS830


Intention-to-treat (ITT) comparisons have a central place in reporting on randomized controlled trials, though there are typically additional analyses of interest such as those making adjustments for nonadherence. In our ITT reporting of results from the Women’s Health Initiative (WHI) randomized trials, we have relied primarily on highly flexible hazard ratio (Cox) regression methods. However, these methods, especially the proportional hazards special case, have been criticized for being difficult to interpret and frequently oversimplified, and for not being consistent with modern causality theories using potential outcomes. Here we address these topics and extend our use of hazard rate methods for ITT comparisons in the WHI trials.

Funding Statement

This work was partially supported by National Institutes of Health awards HHSN268201100046C and P30CA015704.


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Ross L. Prentice. Aaron K. Aragaki. "Intention-to-Treat Comparisons in Randomized Trials." Statist. Sci. 37 (3) 380 - 393, August 2022.


Published: August 2022
First available in Project Euclid: 21 June 2022

MathSciNet: MR4444373
zbMATH: 07569967
Digital Object Identifier: 10.1214/21-STS830

Keywords: causality , Cox model , failure time data , regression , restricted mean survival time

Rights: Copyright © 2022 Institute of Mathematical Statistics

Vol.37 • No. 3 • August 2022
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