Lung function
The lung function test was evaluated by a spirometer (Koko DigiDoser, Louisville, KY, USA) coupled with a microcomputer. The technical procedure, eligibility criteria, and reproducibility were established in accordance with the American Thorax Society and European Respiratory Society recommendations (11). The following variables were assessed: FEV1, FVC, and the FEV1/FVC ratio. Spirometry was performed before and after 400 µg of salbutamol inhaled with an interval of 10 to 15 minutes to evaluate the BD response (11). A positive BD response was considered if a post-BD increase in FEV1 of >12% was predicted from the pre-BD value (11). Values were compared with the values predicted based on data from a Brazilian population, and the LLN was evaluated by a program provided by the Global Lung Initiative (11).