PURPOSE:Though asbestos inhalation has been associated histologically with small airways narrowing, a link between occupational asbestos exposure and clinically meaningful airflow obstruction has not been established.
METHODS:We evaluated spirometry and tobacco use histories from 362 males with long-term workplace asbestos exposure and at least one radiographic marker of asbestos-related disease observed by a certified B reader. From the NHANES I database, a comparison group of 1347 males without X-ray evidence of pneumoconiosis was identified. For the purposes of this study, clinically meaningful airflow obstruction was defined as a ratio of FEV1/FVC < 0.70 and FEV1 percent predicted <0.65.
RESULTS:Overall, the prevalence of airflow obstruction was similar in asbestos exposed individuals (43 of 362, 11.9%) and controls (146 of 1347, 10.8%), p=0.58. Among persons who never smoked, the frequency of obstruction was also similar between the two groups, p=0.57. Among smokers, stratified by lifelong tobacco use, there remained no statistically significant difference in the frequency of obstruction. We used logistic regression to examine the influence of asbestos exposure, age, and pack-years on the presence or absence of airflow obstruction. The overall model was statistically significant, p<0.001. Model odds ratios indicated that, adjusted for tobacco use and age, asbestos exposed individuals were no more likely than controls to have clinically meaningful airflow obstruction, OR=1.09, p=0.65. Smoking history, however, was strongly associated with airflow obstruction. Specifically, persons with 20–40 pack-year and greater than 40 pack-year smoking histories were significantly more likely to have airflow obstruction than those who smoked less than 20 pack-years, OR=2.08, p=0.01 and OR=4.04, p<0.001, respectively. Analyses where obstruction was defined as FEV1/FVC < 0.70 and FEV1 percent predicted < 0.80 yielded similar results.
CONCLUSION:Workplace asbestos exposure sufficient to produce radiographic evidence of asbestos-related disease is not associated with measurable airflow obstruction.
CLINICAL IMPLICATIONS:In patients with occupational exposure to asbestos, measures aimed at preventing obstructive lung disease should focus on known risk factors, particularly cigarette smoke exposure.
DISCLOSURE:John Battaile, No Financial Disclosure Information; No Product/Research Disclosure Information