Janson C, et al. - Different methods for measuring bronchodilator response (BDR) in participants with asthma and COPD were compared. In addition, the extent to which BDR was related to symptom burden and phenotypic characteristics, was examined. From three large international population studies, 35,628 subjects (aged 16 years and older) were examined for forced expiratory volume in one second (FEV1) and forced vital capacity (FVC) before and 15 min after 200 μg of salbutamol. Categorization of the subjects into three groups was done: current asthma (n=2833), COPD (n=1146), and no airway disease (n=31 649). Researchers used three definitions for flow related (increase in FEV1) and three for volume related (increase in FVC). Outcomes revealed that participants with COPD had bronchodilator reversibility at least as common as those with asthma indicating a limited value of measures of reversibility for distinguishing asthma from COPD in population studies. However, bronchodilator reversibility may be a phenotypic marker in asthma.