Duration of asthma and lung function in life-long nonsmoking adults.

BACKGROUND The airways of adult or elderly asthmatics are likely candidates for airway remodeling, resulting in persistent airflow obstruction. This population can provide a good model for cross-sectional evaluation of the effect of asthma duration on airflow. METHODS We evaluated postbronchodilator airflow and lung volumes at baseline and after a short course of oral prednisone in a group of 42 never-smokers with persistent mild or moderate asthma aged 55 years or older. Patients were grouped as having short duration asthma (SDA, <14 years) or long duration asthma (LDA, > or =14 years) according to the median duration of the disease (14 years) of the sample. RESULTS There were no significant differences in patient characteristics or asthma severity indices between the groups. After a short course of prednisone, forced expiratory volume in 1 second (FEV1) and the ratio of FEV to forced vital capacity (FVC) were significantly higher for the SDA group. Only 3 patients presented persistent airflow limitation (FEV1/FVC% < 75%). An inverse correlation was demonstrated between duration of asthma and postbronchodilator FEV1 (% predicted) (r = -0.43, P = .01) and FEV1/FVC% (r = -0.50, P = .003). CONCLUSION Our data show a close relationship between duration of disease and loss of lung function, supporting the concept of asthma as a slow, progressive disease at least among those patients with a mild-to-moderate severity. Permanent airflow obstruction in mild or moderate asthma is unusual, but can occur in a small number suffering from the disease for years.