Siemiatycki J, Wacholder S, Dewar R, Wald L, Bégin D, Richardson L, Rosenman K, Gérin M
Epidemiology and Preventive Medicine Research Centre, Institut Armand-Frappier, Laval-des-Rapides, Quebec, Canada.
Am J Ind Med. 1988;13(1):59-69. doi: 10.1002/ajim.4700130105.
Occupational cohort studies are usually carried out without the benefit of information on smoking habits of cohort members. One common approach to avoid confounding bias related to smoking habits is to carry out an internal analysis, comparing workers with different degrees of occupational exposure. The premise behind this approach is that within a cohort there is unlikely to be correlation between degree of exposure and smoking habits. If this were untrue, smoking could confound the disease-exposure relationships. Our purpose was to verify the premise. The study sample consisted of 857 French-Canadian men born between 1910 and 1930, with 11 or fewer years of education, and interviewed around 1980 in the context of an occupational cancer case-control study. For each man we had information on smoking habits, job history, and a history of the chemicals he was exposed to in each of his jobs. We computed two indices of the dirtiness of workers' job histories: one based on the job titles held by the man and a second based on the degree of exposures to workplace substances. There was no correlation between these indices of job dirtiness and smoking history. We also examined the smoking-exposure relationship among the subsets of men who had been occupationally exposed to ten especially noticeable substances. Within the subsets, there was no indication of a consistent difference among the smoking subgroups in level or duration of exposure to these index substances. These findings do not support the view that nonsmokers sought out cleaner job environments than smokers; they imply that internal analyses of "dose-response" in cohort studies are unlikely to be seriously confounded by smoking habits.
职业队列研究通常在没有队列成员吸烟习惯信息的情况下进行。避免与吸烟习惯相关的混杂偏倚的一种常见方法是进行内部分析，比较不同职业暴露程度的工人。这种方法背后的前提是，在一个队列中，暴露程度与吸烟习惯之间不太可能存在相关性。如果这不是真的，吸烟可能会混淆疾病与暴露之间的关系。我们的目的是验证这一前提。研究样本包括857名1910年至1930年出生的法裔加拿大男性，他们接受的教育年限为11年或更少，并在1980年左右的一项职业癌症病例对照研究中接受了访谈。对于每名男性，我们都有其吸烟习惯、工作经历以及他在每份工作中接触的化学物质的历史信息。我们计算了两个反映工人工作经历“脏污程度”的指标：一个基于男性担任的职位，另一个基于对工作场所物质的暴露程度。这些工作“脏污程度”指标与吸烟史之间没有相关性。我们还研究了职业接触十种特别明显物质的男性子集中的吸烟与暴露关系。在这些子集中，没有迹象表明吸烟亚组在这些指标物质的暴露水平或持续时间上存在一致差异。这些发现不支持非吸烟者比吸烟者寻求更清洁工作环境的观点；它们意味着队列研究中“剂量反应”的内部分析不太可能因吸烟习惯而受到严重混淆。
