Lung function decline in bronchial asthma.

Study Objective: We evaluated the longitudinal changes in lung function and the factors associated with FEV(1) changes over time in a sample of asthmatic subjects.

Setting: FEV(1) measures were recorded every 3 months over a 5-year follow-up period. To compare all subjects independently of body size, FEV(1) values were normalized for the subject's height at the third power.