Smoke, Biomass Exposure, and COPD Risk in the Primary Care Setting: The PUMA Study

BACKGROUND: The evidence indicates that risk factors other than smoking are important in the development of COPD. It has been postulated that less traditional risk factors (eg, exposure to coal and/or biomass smoke) may interact with smoking to further increase COPD risk. This analysis evaluated the effect of exposure to biomass and smoking on COPD risk in a primary care setting in Latin America.

METHODS: Subjects attending routine primary care visits, ≥40 y old, who were current or former smokers or were exposed to biomass smoke, completed a questionnaire and performed spirometry. COPD was defined as post-bronchodilator FEV₁/FVC < 0.70 and the lower limit of normal. Smoking was defined by pack-years (≤ 20, 20−30, or > 30), and biomass exposure was defined as an exposure to coal or wood (for heating, cooking, or both) for ≥ 10 y.

RESULTS: One thousand seven hundred forty-three individuals completed the questionnaire, and 1,540 performed spirometry. Irrespective of COPD definition, approximately 40% of COPD subjects reported exposure to biomass versus 30% of those without COPD. A higher proportion of COPD subjects (post-bronchodilator FEV₁/FVC < 0.70) than those without COPD smoked > 30 pack-years (66% vs 39%); similar results were found with the lower limit of normal definition. Analysis of exposure to biomass > 10 y plus smoking > 20 pack-years (reference was no exposure) found that tobacco smoking (crude odds ratio [OR] 4.50, 95% CI 2.73−7.41; adjusted OR 3.30, 95% CI 1.93−5.63) and biomass exposure (crude OR 3.66, 95% CI 2.00−6.73; adjusted OR 2.28, 95% CI 1.18−4.41) were risk factors for COPD, with smoking a possible confounder for the association between biomass and COPD (post-bronchodilator FEV₁/FVC < 0.70); similar results were found with the lower limit of normal definition.

CONCLUSIONS: Subjects with COPD from primary care had a higher exposure to biomass and smoking compared with non-COPD subjects. Smoking and biomass are both risk factors for COPD, but they do not appear to have an additive effect.