Wang Ziwen, Wang Chenguang, Wang Xiaoguang
School of Mathematical Sciences, Dalian University of Technology, Dalian, Liaoning, China.
Division of Biostatistics and Bioinformatics, Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University, Baltimore, Maryland, USA.
Biom J. 2023 Dec;65(8):e2100357. doi: 10.1002/bimj.202100357. Epub 2023 Sep 6.
In observational studies, covariates are often confounding factors for treatment assignment. Such covariates need to be adjusted to estimate the causal treatment effect. For observational studies with survival outcomes, it is usually more challenging to adjust for the confounding covariates for causal effect estimation because of censoring. The challenge becomes even thornier when there exists a nonignorable cure fraction in the population. In this paper, we propose a causal effect estimation approach in observational studies for survival data with a cure fraction. We extend the absolute treatment effects on survival outcomes-including the restricted average causal effect and SPCE-to survival outcomes with cure fractions, and construct the corresponding causal effect estimators based on propensity score stratification. We prove the asymptotic properties of the proposed estimators and conduct simulation studies to evaluate their performances. As an illustration, the method is applied to a stomach cancer study.
在观察性研究中,协变量往往是治疗分配的混杂因素。为了估计因果治疗效果,需要对这些协变量进行调整。对于具有生存结局的观察性研究,由于存在删失,在调整混杂协变量以估计因果效应时通常更具挑战性。当总体中存在不可忽略的治愈比例时,这一挑战变得更加棘手。在本文中,我们提出了一种针对具有治愈比例的生存数据的观察性研究中的因果效应估计方法。我们将生存结局的绝对治疗效果(包括受限平均因果效应和标准化比例因果效应)扩展到具有治愈比例的生存结局,并基于倾向得分分层构建相应的因果效应估计量。我们证明了所提出估计量的渐近性质,并进行了模拟研究以评估它们的性能。作为一个例证,该方法被应用于一项胃癌研究。