Acute bronchodilator responsiveness in subjects with and without airflow obstruction in five Latin American cities: The PLATINO study

BackgroundAcute bronchodilator responsiveness is an area of discussion in COPD. No information exists regarding this aspect of the disease from an unselected COPD population. We assessed acute bronchodilator responsiveness and factors influencing it in subjects with and without airway obstruction in an epidemiologic sample.MethodsCOPD was defined by GOLD criteria (post-bronchodilator FEV₁/FVC < 0.70). In this analysis, subjects with pre-bronchodilator FEV₁/FVC <0.70 but ≥0.70 post-bronchodilator were considered to have reversible obstruction. Bronchodilator responsiveness after albuterol 200 μg was assessed using three definitions: a) FVC and/or FEV₁ increment ≥12% plus ≥200 mL over baseline; b) FEV₁ ≥ 15% increase over baseline; and c) FEV₁ increase ≥10% of predicted value.ResultsThere were 756 healthy respiratory subjects, 481 subjects with reversible obstruction and 759 COPD subjects. Depending on the criterion used the proportion of person with acute bronchodilator responsiveness ranged between 15.0–28.2% in COPD, 11.4–21.6% in reversible obstructed and 2.7–7.2% in respiratory healthy. FEV₁ changes were lower (110.6 ± 7.40 vs. 164.7 ± 11.8 mL) and FVC higher (146.5 ± 14.2 mL vs. ?131.0 ± 19.6 mL) in COPD subjects compared with reversible obstructed. Substantial overlap in FEV₁ and FVC changes was observed among the groups. Acute bronchodilator responsiveness in COPD persons was associated with less obstruction and never smoking.ConclusionsOver two-thirds of persons with COPD did not demonstrate acute bronchodilator responsiveness. The overall response was small and less than that considered as significant by ATS criteria. The overlap in FEV₁ and FVC changes after bronchodilator among the groups makes it difficult to determine a threshold for separating them.