Intention-to-Treat Comparisons in Randomized Trials

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 theWHI trials.

Automated summary

This article discusses the use of intention-to-treat (ITT) comparisons in randomized controlled trials, particularly in adjusting for nonadherence. The study primarily relies on highly flexible hazard ratio regression methods to report results, but these methods have been criticized for being difficult to interpret, oversimplified, and inconsistent with modern causality theories. The article extends the use of hazard rate methods for ITT comparisons in the Women's Health Initiative trials.