There has been debate on whether the hazard function should be used for causal inference in time-to-event studies. The main criticism is that there is selection bias because the risk sets beyond the first event time are comprised of subsets of survivors who are no longer balanced in the risk factors, even in the absence of unmeasured confounding, measurement error, and model misspecification. In this short communication we use the potential outcomes framework and the single-world intervention graph to show that there is indeed no selection bias when estimating the average treatment effect, and that the hazard ratio over time can provide a useful interpretation in practical settings.

翻译：在时间至事件研究中，关于是否应将风险函数用于因果推断一直存在争议。主要批评在于，即便不存在未测量的混杂因素、测量误差和模型设定错误，由于首个事件时间之后的风险集由不再具有风险因素平衡性的存活者子集构成，因此会存在选择偏倚。在本短讯中，我们利用潜在结果框架和单世界干预图证明，在估计平均处理效应时实际上不存在选择偏倚，并且随时间变化的危险比在实际情境中能够提供有意义的解释。