Ritz Beate, Wilhelm Michelle, Hoggatt Katherine J, Ghosh Jo Kay C
Department of Epidemiology, School of Public Health, University of California, Los Angeles, CA 90095, USA.
Am J Epidemiol. 2007 Nov 1;166(9):1045-52. doi: 10.1093/aje/kwm181. Epub 2007 Aug 4.
The authors conducted a case-control survey nested within a birth cohort and collected detailed risk factor information to assess the extent to which residual confounding and exposure misclassification may impact air pollution effect estimates. Using a survey of 2,543 of 6,374 women sampled from a cohort of 58,316 eligible births in 2003 in Los Angeles County, California, the authors estimated with logistic regression and two-phase models the effects of pregnancy period-specific air pollution exposure on the odds of preterm birth. For the first trimester, the odds of preterm birth consistently increased with increasing carbon monoxide exposures and also at high levels of exposure to particulate matter less than or equal to 2.5 microm in diameter (>21.4 microg/m(3)), regardless of type of data (cohort/sample) or covariate adjustment (carbon monoxide exposures of >1.25 ppm increased the odds by 21-25%). Women exposed to carbon monoxide above 0.91 ppm during the last 6 weeks of pregnancy experienced increased odds of preterm birth. Crude and birth certificate covariate-adjusted results for carbon monoxide differed from each other. However, further adjustment for risk factors assessed in the survey did not change effect estimates for short-term pollutant averages appreciably, except for time-activity patterns, which strengthened the observed associations. These results confirm the importance of reducing exposure misclassification when evaluating the effect of traffic-related pollutants that vary spatially.
作者在一个出生队列中开展了一项病例对照研究，并收集了详细的风险因素信息，以评估残余混杂和暴露错误分类可能对空气污染效应估计产生的影响程度。作者对从加利福尼亚州洛杉矶县2003年符合条件的58316例出生队列中抽取的6374名女性中的2543名进行了调查，采用逻辑回归和两阶段模型估计孕期特定空气污染暴露对早产几率的影响。在孕早期，早产几率随着一氧化碳暴露量的增加以及直径小于或等于2.5微米的颗粒物（>21.4微克/立方米）高暴露水平持续增加，无论数据类型（队列/样本）或协变量调整如何（一氧化碳暴露量>1.25 ppm使几率增加21%-25%）。在怀孕最后6周暴露于一氧化碳浓度高于0.91 ppm的女性早产几率增加。一氧化碳的粗效应和出生证明协变量调整后的结果彼此不同。然而，对调查中评估的风险因素进行进一步调整并没有明显改变短期污染物平均值的效应估计，除了时间-活动模式，它强化了观察到的关联。这些结果证实了在评估空间变化的交通相关污染物的影响时减少暴露错误分类的重要性。
