Weiss W
Hahnemann University, Philadelphia, PA.
J Occup Med. 1989 Feb;31(2):102-5.
The mortality risks of respiratory cancer and of all other causes of death combined were studied in two types of cohort: (1) a cross-sectional cohort composed of all employees working in a chemical plant building in January 1963 when the occupational cause (chloromethyl ethers) of a suspected lung cancer epidemic was unknown, and (2) an inception cohort composed of all workers ever exposed in the building from the beginning of exposure, registered after the cause was recognized. Selection bias led to an overestimate of the risk in the cross-sectional cohort. The bias was due to overrepresentation of workers with moderate and high cumulative exposure to chloromethyl ethers in the cross-sectional cohort. The results indicate that a more valid assessment of an epidemic is obtained from a study of an inception cohort than from a study of a cross-sectional cohort.
（1）一个横断面队列，由1963年1月在一座化工厂大楼工作的所有员工组成，当时疑似肺癌流行的职业病因（氯甲醚）尚不清楚；（2）一个起始队列，由自接触开始就在该大楼中接触过的所有工人组成，在病因被确认后进行登记。选择偏倚导致横断面队列中的风险被高估。该偏倚是由于横断面队列中氯甲醚累积暴露量中等和高的工人比例过高所致。结果表明，与横断面队列研究相比，起始队列研究能对疫情做出更有效的评估。
