Survival of patients with chronic obstructive pulmonary disease due to biomass smoke and tobacco

Rationale: Women exposed chronically to biomass develop airflow limitation, as tobacco smokers do, but their clinical profile and survival have not been described in detail. Objective: To determine the clinical profile, survival, and prognostic factors of chronic obstructive pulmonary disease associated with biomass exposure and tobacco smoking. Methods: During a 7-yr period (1996-2003), a consecutive series of 520 patients were recruited and followed up at the COPD Clinic of the National Institute of Respiratory Diseases. Prognostic factors of survival were evaluated taking into account the interaction between sex and exposure. Measurements: Spirometry, arterial blood gases and oxygen saturation, body mass index, exercise capacity, and health-related quality of life were performed at baseline. The main outcome was survival. Main Results: A total of 481 patients were followed up. The patients in the biomass group, mainly women (84%), were older and shorter and had a greater body mass index than those in the tobacco group (p < 0.0001). Airflow obstruction was more severe in smokers (p < 0.001). Quality of life and distance walked showed similar abnormalities in both groups. In the multivariable Cox regression analysis including an interaction term exposure-sex, we found that age (relative risk [RR], 1.02; 95% confidence interval [CI], 1.02-1.07), FEV1 as percentage of predicted (RR, 0.96; 95% CI, 0.96-0.99), body mass index (RR, 0.95; 95% CI, 0.90-1.01), and oxygen saturation (RR, 0.96; 95% CI, 0.92-0.99) were predictors of mortality but not exposure or sex. Conclusions: Women exposed domestically to biomass develop chronic obstructive pulmonary disease with clinical characteristics, quality of life, and increased mortality similar in degree to that of tobacco smokers.