Estimation of controlled direct effects in time-varying treatments using structural nested mean models: application to a primary prevention trial for coronary events with pravastatin
Estimation of controlled direct effects in time-varying treatments using structural nested mean models: application to a primary prevention trial for coronary events with pravastatin
复制标题
使用结构嵌套均值模型估计时变治疗中的受控直接效应：在普伐他汀冠状动脉事件一级预防试验中的应用
DOI：
10.1002/sim.6162
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发表时间：
2014
影响因子：
2
通讯作者：
Ohashi Y
中科院分区：
文献类型：
--
作者：
Shinozaki T;Matsuyama Y;Ohashi Y
对于受控直接效应的估计（即，直接效应控制中间变量，中间变量为所有人群设定在一个固定的水平上）而无偏倚，两个基本假设必须成立：治疗和结果以及中间变量和结果不存在不可测量的混杂因素。即使这些假设成立，当治疗影响混杂因素时，仍然无法使用标准方法（例如分层或回归建模）估计直接效应。对于这种情况，已经开发了结构嵌套平均模型的序贯g估计方法，用于估计点治疗情况下的受控直接效应。在这项研究中，我们证明了这种方法可以应用于具有时变处理和重复测量中间变量的纵向数据。我们顺序估计两个结构嵌套均值模型中的参数：一个用于重复测量的中间体，另一个用于时变处理的直接效应。该方法被应用于一个大型的一级预防试验的数据，其中普伐他汀用于降低中度高胆固醇血症患者的胆固醇水平。版权所有© 2014约翰威利父子有限公司.
For the estimation of controlled direct effects (i.e., direct effects controlling intermediates that are set at a fixed level for all members of the population) without bias, two fundamental assumptions must hold: the absence of unmeasured confounding factors for treatment and outcome and for intermediate variables and outcome. Even if these assumptions hold, one would nonetheless fail to estimate direct effects using standard methods, for example, stratification or regression modeling, when the treatment influences confounding factors. For such situations, the sequential g‐estimation method for structural nested mean models has been developed for estimating controlled direct effects in point‐treatment situations. In this study, we demonstrate that this method can be applied to longitudinal data with time‐varying treatments and repeatedly measured intermediate variables. We sequentially estimate the parameters in two structural nested mean models: one for a repeatedly measured intermediate and the other one for direct effects of a time‐varying treatment. The method was applied to data from a large primary prevention trial for coronary events, in which pravastatin was used to lower the cholesterol levels in patients with moderate hypercholesterolemia. Copyright © 2014 John Wiley & Sons, Ltd.