The impact of residual and unmeasured confounding in epidemiologic studies: A simulation study
The impact of residual and unmeasured confounding in epidemiologic studies: A simulation study
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DOI：
10.1093/aje/kwm165
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发表时间：
2007-09-15
影响因子：
5
通讯作者：
Sterne, Jonathan A. C.
中科院分区：
文献类型：
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作者：
Fewell, Zoe;Smith, George Davey;Sterne, Jonathan A. C.
在流行病学研究中，解释变量的测量误差和未测量的混杂因素会引起相当大的问题。众所周知，在某些条件下，曝光变量中的非微分测量误差会产生零偏。混杂因素中的测量误差将导致剩余混杂，但这不是一个简单的问题，也不清楚偏倚将指向哪个方向。不可测量的混杂因素使问题更加复杂。由于残留或未测量的混杂因素，暴露效应估计值中可能出现的偏倚量已进行了讨论。在本文中，作者使用模拟研究和逻辑回归分析，调查的规模明显的风险结果的关联，可以发生时，在事实上的曝光没有因果关系的结果。作者考虑了两个正态分布暴露和两个或四个正态分布混杂因素的病例。当混杂因素不相关时，暴露效应估计的偏倚随着剩余和未测量混杂因素的增加而增加。相关混杂因素的模式更为复杂。在合理的假设下，观察性流行病学研究中经常报告的效应量大小可以单独由残差和/或未测量的混杂因素产生。
Measurement error in explanatory variables and unmeasured confounders can cause considerable problems in epidemiologic studies. It is well recognized that under certain conditions, nondifferential measurement error in the exposure variable produces bias towards the null. Measurement error in confounders will lead to residual confounding, but this is not a straightforward issue, and it is not clear in which direction the bias will point. Unmeasured confounders further complicate matters. There has been discussion about the amount of bias in exposure effect estimates that can plausibly occur due to residual or unmeasured confounding. In this paper, the authors use simulation studies and logistic regression analyses to investigate the size of the apparent exposure-outcome association that can occur when in truth the exposure has no causal effect on the outcome. The authors consider two cases with a normally distributed exposure and either two or four normally distributed confounders. When the confounders are uncorrelated, bias in the exposure effect estimate increases as the amount of residual and unmeasured confounding increases. Patterns are more complex for correlated confounders. With plausible assumptions, effect sizes of the magnitude frequently reported in observational epidemiologic studies can be generated by residual and/or unmeasured confounding alone.