Dehbi Hakim-Moulay, Royston Patrick, Hackshaw Allan
Cancer Research UK and UCL Cancer Trials Centre, 90 Tottenham Court Road, London, W1T 4TJ, UK
MRC Clinical Trials Unit at UCL, Aviation House, 125 Kingsway Road, London, WC2B 6NH, UK.
BMJ. 2017 May 25;357:j2250. doi: 10.1136/bmj.j2250.
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.
风险比（HR）是在使用生存等事件发生时间结局的临床试验中衡量治疗效果最常用的指标。当生存曲线交叉或仅在相当长的时间后才分开时，Cox模型的比例风险假设就会被违反，此时HR可能会产生误导。对于HR随时间变化的情况，我们提出了两种治疗效果的衡量指标：预期寿命差异（LED）和预期寿命比（LER）。LED是干预组和对照组平均生存时间的差值。LER是这两个时间的比值。在试验期间至少可以针对两个时间间隔计算LED和LER，适用于治疗效果随时间变化的曲线。这两个指标很容易被解释为预期寿命的绝对和相对增减。
