Lisonkova Sarka, Joseph K S
From the aDepartment of Obstetrics & Gynaecology, University of British Columbia and the Children's and Women's Hospital and Health Centre of British Columbia, Vancouver, Canada; and bSchool of Population and Public Health, University of British Columbia, Vancouver, Canada.
Epidemiology. 2015 May;26(3):436-40. doi: 10.1097/EDE.0000000000000268.
We carried out a study to examine whether left truncation bias could explain the negative association between smoking and preeclampsia.
Monte Carlo and other simulation models were used to determine the effect of differential rates of early pregnancy loss among smokers on the relation between smoking and preeclampsia at ≥20 weeks' gestation. Assumptions included no association between smoking and the abnormal placentation that characterizes preeclampsia, and higher rates of early pregnancy loss among smokers, pregnancies with abnormal placentation, and smokers with abnormal placentation.
Monte Carlo simulation yielded a rate ratio for preeclampsia, given smoking of 0.85 (95% confidence interval = 0.73, 0.98). The protective effect of smoking was also evident in simulations that did not require assumptions about early pregnancy loss rates.
Left truncation bias due to differential rates of early pregnancy loss among smokers is a plausible explanation for the inverse association between maternal smoking and preeclampsia.
我们开展了一项研究，以检验左截断偏倚是否能够解释吸烟与子痫前期之间的负相关关系。
采用蒙特卡洛模拟和其他模拟模型，来确定吸烟者中早期妊娠丢失率差异对吸烟与妊娠≥20周时子痫前期之间关系的影响。假设包括吸烟与子痫前期特征性的胎盘异常植入之间无关联，以及吸烟者、胎盘异常植入的妊娠和胎盘异常植入的吸烟者中早期妊娠丢失率更高。
蒙特卡洛模拟得出，吸烟情况下子痫前期的率比为0.85（95%置信区间=0.73, 0.98）。在不需要对早期妊娠丢失率进行假设的模拟中，吸烟的保护作用也很明显。
吸烟者中早期妊娠丢失率差异导致的左截断偏倚，是孕产妇吸烟与子痫前期之间负相关关系的一个合理的解释。
