When Is the Difference Method Conservative for Assessing Mediation?
When Is the Difference Method Conservative for Assessing Mediation?
复制标题
DOI：
10.1093/aje/kwv059
复制
发表时间：
2015-07-15
影响因子：
5
通讯作者：
VanderWeele, Tyler J.
中科院分区：
文献类型：
--
作者：
Jiang, Zhichao;VanderWeele, Tyler J.
间接效应的评估对于有兴趣了解发病率-结果关系机制的流行病学家是有用的。估计间接影响的传统方法是使用“差异法”，该方法基于回归分析，即在回归模型中加入一个可能的中介因素，并检查暴露系数是否发生变化。差异法被批评为缺乏因果解释时，它与逻辑回归。在本文中，我们使用反事实框架来定义自然间接效应（NIE），并评估NIE和差异方法之间的关系。我们表明，在适当的假设下，差分方法一致地估计NIE连续的结果，总是保守的二元结果。因此，差异法可以用来证明存在调解，但不能证明不存在调解。
Assessment of indirect effects is useful for epidemiologists interested in understanding the mechanisms of exposure-outcome relationships. A traditional way of estimating indirect effects is to use the "difference method," which is based on regression analysis in which one adds a possible mediator to the regression model and examines whether the coefficient for the exposure changes. The difference method has been criticized for lacking a causal interpretation when it is used with logistic regression. In this article, we use the counterfactual framework to define the natural indirect effect (NIE) and assess the relationship between the NIE and the difference method. We show that under appropriate assumptions, the difference method consistently estimates the NIE for continuous outcomes and is always conservative for binary outcomes. Thus, the difference method can be used to provide evidence for the presence of mediation but not for the absence of mediation.