Occupational Exposures and COPD: An Ecological Analysis of International Data
P.D. Blanc 1*,
A.M.B. Menezes 2,
E. Plana 3,
D.M. Mannino 4,
P.C. Hallal 2,
K. Toren 5,
M.D. Eisner 1,
J-P. Zock 3
1 Division of Occupational and Environmental Medicine University of California San Francisco
2 Federal University of Pelotas, Pelotas, Brazil
3 Centre for Research in Environmental Epidemiology, (CREAL), Barcelona, Spain; Municipal Institute of Medical Research (IMIM-Hospital del Mar), Barcelona, Spain; and CIBER Epidemiología y Salud Pública (CIBERESP), Spain
4 University of Kentucky, Lexington, KY, USA
5 Dept of Occupational and Environmental Medicine, Sahlgrenska University Hospital, Göteborg, Sweden
* To whom correspondence should be addressed. E-mail: paul.blanc{at}ucsf.edu.
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Abstract |
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The occupational contribution to chronic obstructive pulmonary disease (COPD) has yet to be put in a global perspective. We used an ecological approach to this question, analyzing group-level data from 90 gender-specific strata from 45 sites of the Burden of Obstructive Lung Disease (BOLD) study; the Latin American Project for the Investigation of Obstructive Lung Disease (PLATINO); and the European Community Respiratory Health Survey follow-up (ECRHS II). We used these data to study the association between occupational exposures and COPD Stage II or above (Global Obstructive Lung Disease [GOLD]). We regressed the gender- specific group-level prevalence rates of COPD at each site against the prevalence of occupational exposure and ever smoking, taking into account mean smoking pack years and mean age by site, gender, study cohort, and sample size. For the entire data set, the prevalence of exposures predicted COPD prevalence (0.8% increase in COPD prevalence per 10% increase in exposure prevalence, p=0.003). By comparison, for every 10% increase in the proportion of the ever smoking population, the prevalence of COPD GOLD Stage II or above increased by 1.3% (p<0.0001). Given the observed median population COPD prevalence of 3.4%, the model predicts that a 20% relative reduction in the disease burden (i.e., to a COPD prevalence of 2.7%) could be achieved by a 5.4% reduction in overall smoking rates or an 8.8% reduction in the prevalence of occupational exposures. When the data set was analyzed by sex-specific site data , among men, the occupational effect was a 0.8% COPD prevalence increase per 10% change in exposure prevalence (p=0.004); among women, a 1.0% increase in COPD per 10% change in exposure prevalence (p=0.03). Within the limitations of an ecological analysis, these findings support a worldwide association between dusty trades and COPD for both women and men, placing this within the context of the dominant role of cigarette smoking in COPD causation.
