Left Truncation Bias to Explain the Protective Effect of Smoking on Preeclampsia Potential, But How Plausible?
Left Truncation Bias to Explain the Protective Effect of Smoking on Preeclampsia Potential, But How Plausible?
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DOI：
10.1097/ede.0000000000000632
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发表时间：
2017-05-01
期刊：
影响因子：
5.4
通讯作者：
Keil, Alexander P.
中科院分区：
文献类型：
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作者：
Kinlaw, Alan C.;Buckley, Jessie P.;Keil, Alexander P.
背景：几十年来，流行病学研究中经常观察到母亲吸烟与先兆子痫之间存在负相关关系。在本杂志 2015 年 5 月号中，Lisonkova 和 Joseph 描述了一项模拟研究，表明左截断的偏差可能可以解释反向关联。这些模拟基于关于可能发生偏差的潜在机制的强有力的假设。方法：为了检查先前作者的结论对这些假设的敏感性，我们使用已发布的估计构建了一个新的蒙特卡洛模拟来构建我们的数据生成参数。我们评估了一系列包括异常胎盘和早期妊娠流产的情况下吸烟与先兆子痫之间的关联。结果：我们的结果证实，先前作者的研究结果高度依赖于关于异常胎盘与先兆子痫之间关联强度的假设。因此，他们描述的偏差可能没有建议的那么明显。结论：在这些关键假设的经验得出的约束下，左截断似乎不能完全解释吸烟与先兆子痫之间的负相关。此外，在考虑暴露可能导致左截断的过程时，在评估潜在偏差之前准确描述目标人群和感兴趣的参数非常重要。在将孕产妇吸烟和先兆子痫作为公共卫生问题进行评估时，我们对有意义的目标人群的规范进行了评论。我们描述了在围产期暴露研究中定义目标人群的考虑因素，当这些暴露导致主要结果的竞争事件（例如，早孕流产）时。
Background: An inverse association between maternal smoking and preeclampsia has been frequently observed in epidemiologic studies for several decades. In the May 2015 issue of this journal, Lisonkova and Joseph described a simulation study suggesting that bias from left truncation might explain the inverse association. The simulations were based on strong assumptions regarding the underlying mechanisms through which bias might occur.Methods: To examine the sensitivity of the previous authors' conclusions to these assumptions, we constructed a new Monte Carlo simulation using published estimates to frame our data-generating parameters. We estimated the association between smoking and preeclampsia across a range of scenarios that incorporated abnormal placentation and early pregnancy loss.Results: Our results confirmed that the previous authors' findings are highly dependent on assumptions regarding the strength of association between abnormal placentation and preeclampsia. Thus, the bias they described may be less pronounced than was suggested.Conclusions: Under empirically derived constraints of these critical assumptions, left truncation does not appear to fully explain the inverse association between smoking and preeclampsia. Furthermore, when considering processes in which left truncation may result from the exposure, it is important to precisely describe the target population and parameter of interest before assessing potential bias. We comment on the specification of a meaningful target population when assessing maternal smoking and preeclampsia as a public health issue. We describe considerations for defining a target population in studies of perinatal exposures when those exposures cause competing events (e.g., early pregnancy loss) for primary outcomes of interest.