Asthma–COPD overlap syndrome (ACOS) in primary care of four Latin America countries: the PUMA study

BACKGROUND Asthma-COPD overlap syndrome (ACOS) prevalence varies depending on the studied population and definition criteria. The prevalence and clinical characteristics of ACOS in an at-risk COPD primary care population from Latin America was assessed. METHODS Patients ≥40 years, current/ex-smokers and/or exposed to biomass, attending routine primary care visits completed a questionnaire and performed spirometry. COPD was defined as post-bronchodilator forced expiratory volume in 1 s/forced vital capacity (FEV1/FVC) < 0.70; asthma was defined as either prior asthma diagnosis or wheezing in the last 12 months plus reversibility (increase in post-bronchodilator FEV1 or FVC ≥200 mL and ≥12%); ACOS was defined using a combination of COPD with the two asthma definitions. Exacerbations in the past year among the subgroups were evaluated. RESULTS One thousand seven hundred forty three individuals completed the questionnaire, 1540 performed acceptable spirometry, 309 had COPD, 231 had prior asthma diagnosis, and 78 asthma by wheezing + reversibility. ACOS prevalence in the total population (by post-bronchodilator FEV1/FVC < 0.70 plus asthma diagnosis) was 5.3 and 2.3% by post-bronchodilator FEV1/FVC < 0.70 plus wheezing + reversibility. In the obstructive population (asthma or COPD), prevalence rises to 17.9 and 9.9% by each definition, and to 26.5 and 11.3% in the COPD population. ACOS patients defined by post-bronchodilator FEV1/FVC < 0.7 plus wheezing + reversibility had the lowest lung function measurements. Exacerbations for ACOS showed a prevalence ratio of 2.68 and 2.20 (crude and adjusted, p < 0.05, respectively) (reference COPD). CONCLUSIONS ACOS prevalence in primary care varied according to definition used. ACOS by post-bronchodilator FEV1/FVC < 0.7 plus wheezing + reversibility represents a clinical phenotype with more frequent exacerbations, which is probably associated with a different management approach.