In medical and epidemiological studies, one of the most common settings is studying the effect of a treatment on a time-to-event outcome, where the time-to-event might be censored before end of study. A common parameter of interest in such a setting is the marginal hazard ratio (MHR). When a study is based on observational data, propensity score (PS) based methods are often used, in an attempt to make the treatment groups comparable despite having a non-randomized treatment. Previous studies have shown censoring to be a factor that induces bias when using PS based estimators. In this paper we study the magnitude of the bias under different rates of non-informative censoring when estimating MHR using PS weighting or PS matching. A bias correction involving the probability of event is suggested and compared to conventional PS based methods.

翻译：在医学和流行病学研究中，最常见的场景之一是评估治疗对事件发生时间结局的影响，其中事件发生时间可能在研究结束前被删失。此类场景中的常见目标参数是边际风险比（MHR）。当研究基于观察性数据时，通常采用基于倾向性评分（PS）的方法，以在非随机化治疗的情况下使治疗组具有可比性。既往研究表明，在使用基于PS的估计量时，删失是导致偏倚的因素。本文研究了在使用PS加权或PS匹配估计MHR时，不同非信息性删失率下的偏倚程度。我们提出了一种涉及事件概率的偏倚校正方法，并将其与传统基于PS的方法进行了比较。