Effects of Age on 1-Second Forced Expiratory Volume Response to Bronchodilation

Background: The bronchodilation test is used to detect reversible airways obstruction, considered important for diagnosing asthma. However, little is known about the effects of age on the bronchodilation response. The aim of this study was to evaluate the effects of age on the bronchodilation response by determining changes in the 1-second forced expiratory volume (FEV1) in a Chinese population. Methods: All patients underwent pulmonary function testing to evaluate forced vital capacity, peak expiratory flow, and FEV1. We assessed bronchodilation by measuring the change in FEV1 (ΔFEV1) before and after inhalation of 0.4mg of fenoterol (two puffs) delivered by a metered-dose inhaler with a spacer. Results: Of the 1,616 patients tested in the clinic, the 333 (21%) who had a positive bronchodilator test, defined as ΔFEV1 > 12% and 200mL, were enrolled in the study. For this population, the ΔFEV1 was +360.8 ± 138.6mL (mean ± standard deviation) or + 21.0% ± 9.1%. In a multiple linear regression model, the absolute ΔFEV1 (expressed in milliliters) was independently and negatively predicted by age (p < 0.001), and baseline peak expiratory flow (p < 0.001), but positively predicted by height (p < 0.001). Conclusion: Age was an important determinant for response to bronchodilation as determined by the absolute change in FEV1