Department of Environmental Medicine and Behavioral Science, Kinki University School of Medicine, 377-2 Ohno-higashi, Osakasayama, Osaka, Japan.
Am J Epidemiol. 2011 Apr 1;173(7):745-51. doi: 10.1093/aje/kwq418. Epub 2011 Feb 25.
In randomized trials with follow-up, outcomes such as quality of life may be undefined for individuals who die before the follow-up is complete. In such settings, restricting analysis to those who survive can give rise to biased outcome comparisons. An alternative approach is to consider the "principal strata effect" or "survivor average causal effect" (SACE), defined as the effect of treatment on the outcome among the subpopulation that would have survived under either treatment arm. The authors describe a very simple technique that can be used to assess the SACE. They give both a sensitivity analysis technique and conditions under which a crude comparison provides a conservative estimate of the SACE. The method is illustrated using data from the ARDSnet (Acute Respiratory Distress Syndrome Network) clinical trial comparing low-volume ventilation and traditional ventilation methods for individuals with acute respiratory distress syndrome.
在随访的随机试验中，对于在随访完成前死亡的个体，生活质量等结局可能无法定义。在这种情况下，将分析仅限于存活者可能会导致有偏的结局比较。另一种方法是考虑“主要层效果”或“存活者平均因果效应”（SACE），定义为治疗对两种治疗组中任何一组均存活的亚人群的结局的影响。作者描述了一种非常简单的技术，可用于评估 SACE。他们给出了一种敏感性分析技术和在何种条件下，粗略比较可提供 SACE 的保守估计。该方法使用来自 ARDSnet（急性呼吸窘迫综合征网络）临床试验的数据进行了说明，该试验比较了急性呼吸窘迫综合征患者的低容量通气和传统通气方法。
