Marsh G M, Youk A O, Collins J J
Department of Biostatistics, Graduate School of Public Health, University of Pittsburgh, Pennsylvania 15261, USA.
Scand J Work Environ Health. 2001 Feb;27(1):5-13. doi: 10.5271/sjweh.581.
The present study provides additional analyses of data obtained earlier on lung cancer risk among workers with acrylonitrile exposure.
The original authors provided the data. For total mortality and the cancer sites of a priori interest (lung, stomach, brain, breast, prostate, and the lymphatic and hematopoietic systems), standardized mortality ratios (SMR) and 95% confidence intervals (95% CI) were computed, the total United States and surrounding counties being used as standard populations. Regional rate-based SMR values were also computed between lung cancer and cumulative acrylonitrile exposure.
Except for lung cancer, the external comparisons corroborated the earlier internal comparisons (no increased cancer mortality risk). For lung cancer, the external comparisons revealed death deficits for the unexposed workers (SMR 0.68, 95% CI 0.5-0.9) and all categories of acrylonitrile-exposed workers. The SMR obtained using external rates and the most exposed group (SMR 0.92. 95% CI 0.6-1.4) differed from the corresponding relative risk (RR) of the internal rates (RR 1.5, 95% CI 0.9-2.4).
The analysis of the present study provides little evidence that acrylonitrile exposure increases the mortality risk of cancers of a priori interest, including lung cancer. The lung cancer findings of the external comparison differed from the earlier findings of the internal comparisons. Selection bias (as the healthy worker effect) was probably not responsible. Additional follow-up and analyses, especially of the unexposed workers with low lung cancer rates, may help elucidate the internal and external comparison differences. Results from both comparisons should be presented when the relative risks differ markedly, as both have advantages and disadvantages.
本研究对早期获得的丙烯腈接触工人肺癌风险数据进行了补充分析。
原始作者提供了数据。对于总死亡率和预先关注的癌症部位（肺癌、胃癌、脑癌、乳腺癌、前列腺癌以及淋巴和造血系统），计算了标准化死亡比（SMR）和95%置信区间（95%CI），以美国总体人群和周边县作为标准人群。还计算了肺癌与累积丙烯腈接触之间基于区域发病率的SMR值。
除肺癌外，外部比较证实了早期的内部比较结果（癌症死亡风险未增加）。对于肺癌，外部比较显示未接触工人（SMR 0.68，95%CI 0.5 - 0.9）以及所有丙烯腈接触类别的工人存在死亡不足情况。使用外部发病率和最高接触组获得的SMR（SMR 0.92，95%CI 0.6 - 1.4）与内部发病率的相应相对风险（RR 1.5，95%CI 0.9 - 2.4）不同。
本研究分析几乎没有证据表明丙烯腈接触会增加预先关注的癌症（包括肺癌）的死亡风险。外部比较的肺癌研究结果与早期内部比较结果不同。选择偏倚（如健康工人效应）可能不是原因。额外的随访和分析，特别是对肺癌发病率较低的未接触工人进行分析，可能有助于阐明内部和外部比较的差异。当相对风险有显著差异时，应同时呈现两种比较的结果，因为两者都有优缺点。
