Tse Lap Ah, Yu Ignatius Tak-Sun
Department of Community & Family Medicine, The Chinese University of Hong Kong, HKSAR.
Zhonghua Liu Xing Bing Xue Za Zhi. 2007 Jan;28(1):88-91.
Previously documented indirect adjustment methods could only adjust for the confounding effects from cigarette smoking. The aim of this paper is to introduce a novel method for dealing with the effects of smoking in occupational, epidemiological cohort studies using a 'smoking adjustment factor'.
A retrospective cohort study among male silicotic workers purely exposed to silica dusts in Hong Kong (1981 - 1999) was used as an example. 'Smoking adjustment factor' in occupationally exposed smoking and nonsmoking sub-cohorts was expressed as 1/(1- PAR% )xRR and 1/1- PAR% respectively. Relative exposure effect and Synergy index were estimated to assess the multiplicative and additive interactions.
'Smoking adjustment factor' for non-smoking and smoking silicotic workers was 1/0.33 and 1/1.62 respectively. Lung cancer standardized mortality ratio(SMR) of all cohort members was reduced from 1.61(95% CI: 1.22-2.10) to 1.08(95% CI:0.81-1.41) after indirectly adjusted for smoking effect. Results from our novel indirect method were in line with that from Axelson' s approach. Relative silicosis effect and synergy index were estimated to be 0.63 (95% CI:0.08-0.79) and 0.90 (95 % CI:0.42-1.94) ,suggesting a significant but negative multiplicative interaction between smoking and silicosis on the risk of lung cancer mortality.
The merit of this new method was the ability to adjust for the confounding effect and evaluate the interactive effect with smoking. However, comparability of age distribution between occupationally exposed smoking and nonsmoking sub-cohorts was a prerequisite for the accurate estimations of the smoking indirectly adjusted SMR, relative exposure effect, and/or synergy index.
先前记录的间接调整方法只能调整吸烟的混杂效应。本文的目的是介绍一种在职业性、流行病学队列研究中使用“吸烟调整因子”来处理吸烟影响的新方法。
以香港（1981 - 1999年）纯接触矽尘的男性矽肺工人的回顾性队列研究为例。职业暴露吸烟和非吸烟亚队列中的“吸烟调整因子”分别表示为1/(1 - PAR%)×RR和1/(1 - PAR%)。估计相对暴露效应和协同指数以评估相乘和相加相互作用。
非吸烟和吸烟矽肺工人的“吸烟调整因子”分别为1/0.33和1/1.62。在对吸烟效应进行间接调整后，所有队列成员的肺癌标准化死亡比（SMR）从1.61（95%CI：1.22 - 2.10）降至1.08（95%CI：0.81 - 1.41）。我们新的间接方法的结果与Axelson方法的结果一致。估计相对矽肺效应和协同指数分别为0.63（95%CI：0.08 - 0.79）和0.90（95%CI：0.42 - 1.94），表明吸烟和矽肺在肺癌死亡风险上存在显著但为负的相乘相互作用。
这种新方法的优点是能够调整混杂效应并评估与吸烟的交互效应。然而，职业暴露吸烟和非吸烟亚队列之间年龄分布的可比性是准确估计吸烟间接调整的SMR、相对暴露效应和/或协同指数的前提条件。
