Influence of smoking on radiographic profusion and pleural changes in asbestos-exposed subjects

The influence of smoking on pleural and parenchymal radiographic changes, particularly in asbestos-exposed cohorts, has been debated. We studied this issue in 440 asbestos-exposed subjects referred for evaluation between 1981 and 1985. Information was obtained on age, exposure, and smoking. Chest radiographs were independently read by three "B" readers under blind conditions and it was determined that 80.5% of the subjects had a history of smoking. The odds ratio for smoking and parenchymal opacities greater than or equal to 1/0 was 1.98 (95% confidence interval, 1.2 to 3.3); this association was not affected by adjustment for asbestos exposure and/or age. A dose-response pattern emerged between increasing pack-years and parenchymal opacities greater than or equal to 1/0; the effect between asbestos exposure and smoking appeared to be additive. No associations were found between smoking and pleural abnormalities. The findings in this investigation are consistent with prior studies showing an influence of smoking on radiographic parenchymal, but not pleural, changes, at least in asbestos-exposed groups. The anatomical equivalent of these radiographic changes and their impact, if any, on the natural history of asbestos-associated disease remains unclear.