Chu Fang-I, Wang Yuedong
Department of Radiation Oncology, University of California, Los Angeles, Los Angeles, CA, US.
Department of Statistics and Applied Probability, University of California, Santa Barbara, Santa Barbara, CA, US.
Commun Stat Theory Methods. 2023;52(15):5145-5154. doi: 10.1080/03610926.2021.2004423. Epub 2021 Nov 30.
Vascular access for hemodialysis is of paramount importance. Although studies have found that central venous catheter (CVC) is often associated with poor outcomes and switching to arteriovenous fistula (AVF) and arteriovenous grafts (AVG) is beneficial, it has not been fully elucidated how the effect of switching of access on outcomes changes over time and whether the effect depends on switching time. In this paper we propose to relate the observed survival time for patients without access change and the counterfactual time for patients with access change using an AFT model with time-varying effects. The flexibility of AFT model allows us to account for baseline effect and the prognostic effect from covariates at access change while estimating the effect of access change. The effect of access change overtime is modeled nonparametrically using a cubic spline function. Simulation studies show excellent performance. Our methods are applied to investigate the effect of vascular access change over time in dialysis patients. It is concluded that the benefit of switching from CVC to AVG depends on the time of switching, the sooner the better.
血液透析的血管通路至关重要。尽管研究发现中心静脉导管（CVC）常常与不良预后相关，且转为动静脉内瘘（AVF）和动静脉移植物（AVG）有益，但接入方式转换对预后的影响如何随时间变化以及这种影响是否取决于转换时间尚未完全阐明。在本文中，我们建议使用具有时变效应的加速失效时间（AFT）模型，将未改变接入方式患者的观察生存时间与改变接入方式患者的反事实时间联系起来。AFT模型的灵活性使我们在估计接入方式改变的影响时，能够考虑基线效应以及接入方式改变时协变量的预后效应。接入方式随时间的变化效应使用三次样条函数进行非参数建模。模拟研究显示出良好的性能。我们的方法被应用于研究透析患者血管通路随时间的变化效应。得出的结论是，从CVC转换为AVG的益处取决于转换时间，越早越好。
