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On the clinical meaningfulness of a treatment's effect on a time‐to‐event variable
Author(s) -
Snapinn Steven,
Jiang Qi
Publication year - 2011
Publication title -
statistics in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.996
H-Index - 183
eISSN - 1097-0258
pISSN - 0277-6715
DOI - 10.1002/sim.4256
Subject(s) - event (particle physics) , contradiction , variable (mathematics) , proportional hazards model , statistics , hazard ratio , hazard , econometrics , mathematics , medicine , confidence interval , epistemology , philosophy , mathematical analysis , physics , chemistry , organic chemistry , quantum mechanics
The standard analysis of a time‐to‐event variable often involves the calculation of a hazard ratio based on a survival model such as Cox regression; however, many people consider such relative measures of effect to be poor expressions of clinical meaningfulness. Two absolute measures of effect are often used to assess clinical meaningfulness: (1) many disease areas frequently use the absolute difference in event rates (or its inverse, the number‐needed‐to‐treat) and (2) oncology frequently uses the difference between the median survival times in the two groups. While both of these measures appear reasonable, they directly contradict each other. This paper describes the basic mathematics leading to the two measures and shows examples. The contradiction described here raises questions about the concept of clinical meaningfulness. Copyright © 2011 John Wiley & Sons, Ltd.