Comments on The clinical meaningfulness of a treatment's effect on a time-to-event variable

TL;DR

This paper critiques prior claims about the interpretation of treatment effects on time-to-event outcomes, emphasizing that both absolute and relative measures have valid roles in clinical assessment.

Contribution

It clarifies the limitations of previous analytical conclusions, advocating for the continued use of both absolute and relative effect measures in clinical evaluations.

Findings

Absolute and relative measures can both be valid in different contexts

Hazard ratio depends on shape parameter and baseline risk, but not solely on hazard ratio

Previous claims about the invalidity of absolute measures are not universally applicable

Abstract

Some years ago, Snapinn and Jiang[1] considered the interpretation and pitfalls of absolute versus relative treatment effect measures in analyses of time-to-event outcomes. Through specific examples and analytical considerations based solely on the exponential and the Weibull distributions they reach two conclusions: 1) that the commonly used criteria for clinical effectiveness, the ARR (Absolute Risk Reduction) and the median (survival time) difference (MD) directly contradict each other and 2) cost-effectiveness depends only the hazard ratio(HR) and the shape parameter (in the Weibull case) but not the overall baseline risk of the population. Though provocative, the first conclusion does not apply to either the two special cases considered or even more generally, while the second conclusion is strictly correct only for the exponential case. Therefore, the implication inferred by the authors i.e. all measures of absolute treatment effect are of little value compared with the relative measure of the hazard ratio, is not of general validity and hence both absolute and relative measures should continue to be used when appraising clinical evidence.