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

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.

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.

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.

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.