Chest
Clinical Investigations: Occupational/Pulmonary FunctionEmphysema in Silica- and Asbestos-Exposed Workers Seeking Compensation: A CT Scan Study
Section snippets
Subjects
The 207 patients of the study were consecutive subjects referred to our two committees in Montréal and Sherbrooke by the Workers' Compensation Board of Québec for diagnosis of possible lung disease associated with long-term exposure to mineral dusts. On request by a worker claiming possible occupational lung disease, the Board refers all claimants to the nearest committee, without any winnowing process. Their chest radiographs were read by the three-member committees in the International Labor
RESULTS
The anthropometric and clinical data presented in Table 1 documented that distribution of exposed subjects was balanced among exposure type, industry type, and smoking index (no significant differences by χ2 or ANOVA statistics). There were small differences in age, the asbestos-exposed subjects being slightly older, and those with asbestosis having restrictive lung function changes. Separate analyses of primary or secondary industry workers documented changes in the same direction, with lower
Potential Sources of Bias
Our study has the bias of a population selected on the basis of referral for possible Workman's Compensation and on the ILO category 0 or 1 chest radiographs. It is neither a cross-sectional nor cohort epidemiologic study. The criterion ILO category 0 or 1 chest radiograph was used to avoid the subjects with the most advanced silicosis, in whom emphysema is a well-accepted complication21,22 and contributes to the worker's disability. The population of this study is fairly representitive of the
CONCLUSION
In Workers Compensation Board-referred subjects with category 0 or 1 pneumoconiosis, we found a significant excess of CT scan emphysema, associated with lung dysfunction. Prevalence of emphysema was increased in those with pneumoconioses and in smokers with silica exposure. These changes contributed to the lung function impairment of these subjects. In lifetime nonsmokers, emphysema was a component of the pneumoconioses. Simple mineral dust exposure, in absence of smoking, pneumoconiosis, or
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Supported by MRC Canada.