UCL Discovery
UCL home » Library Services » Electronic resources » UCL Discovery

Life expectancy difference and life expectancy ratio: two measures of treatment effects in randomised trials with non-proportional hazards

Dehbi, H-M; Royston, P; Hackshaw, A; (2017) Life expectancy difference and life expectancy ratio: two measures of treatment effects in randomised trials with non-proportional hazards. BMJ (357) , Article j2250. 10.1136/bmj.j2250. Green open access

[thumbnail of bmj.j2250.full(1).pdf]
Preview
Text
bmj.j2250.full(1).pdf - Published Version

Download (1MB) | Preview

Abstract

The hazard ratio (HR) is the most common measure of treatment effect in clinical trials that use time-to-event outcomes such as survival. When survival curves cross over or separate only after a considerable time, the proportional hazards assumption of the Cox model is violated, and HR can be misleading. We present two measures of treatment effects for situations where the HR changes over time: the life expectancy difference (LED) and life expectancy ratio (LER). LED is the difference between mean survival times in the intervention and control arms. LER is the ratio of these two times. LED and LER can be calculated for at least two time intervals during the trial, allowing for curves where the treatment effect changes over time. The two measures are readily interpretable as absolute and relative gains or losses in life expectancy.

Type: Article
Title: Life expectancy difference and life expectancy ratio: two measures of treatment effects in randomised trials with non-proportional hazards
Open access status: An open access version is available from UCL Discovery
DOI: 10.1136/bmj.j2250
Publisher version: http://dx.doi.org/10.1136/bmj.j2250
Language: English
Additional information: This is an Open Access article distributed in accordance with the terms of the Creative Commons Attribution (CC BY 4.0) license, which permits others to distribute, remix, adapt and build upon this work, for commercial use, provided the original work is properly cited. See: http://creativecommons.org/licenses/by/4.0/.
Keywords: Science & Technology, Life Sciences & Biomedicine, Medicine, General & Internal, General & Internal Medicine
UCL classification: UCL
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Medical Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Medical Sciences > Cancer Institute
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Medical Sciences > Cancer Institute > CRUK Cancer Trials Centre
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Population Health Sciences > Inst of Clinical Trials and Methodology
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Population Health Sciences > Inst of Clinical Trials and Methodology > Comprehensive CTU at UCL
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Population Health Sciences > Inst of Clinical Trials and Methodology > MRC Clinical Trials Unit at UCL
URI: https://discovery.ucl.ac.uk/id/eprint/1558502
Downloads since deposit
0Downloads
Download activity - last month
Download activity - last 12 months
Downloads by country - last 12 months

Archive Staff Only

View Item View Item