Changes in forced expiratory volume in 1 second over time in patients with controlled asthma at baseline

A predominant feature of asthma is an accelerated rate of decline in forced expiratory volume in 1 s (FEV1), but data on the variability and factors associated with this change in patients with controlled asthma are largely unknown.

140 patients with controlled asthma were enrolled based on the Global Initiative for Asthma guidelines. We examined the data of a prospective analysis of the association between asthma control and change in FEV1 over time.

A 3-year follow-up assessment was completed in 128 patients. The mean rate of change in FEV1 was a decline of 22.2 mL yr(-1), with significant variation in the levels of change. The between patient standard deviation for the rate of decline was 34.1 mL yr(-1). We next classified the subjects of less than the 25th percentile as rapid decliners, and greater than the 25th percentile as non-rapid decliners. The decrease in the Asthma Control Test score over a 3-year period was higher for rapid decliners than that for non-rapid decliners (p < 0.001). The rapid decliner was more likely to be older, to have higher levels of FeNO, and to have had severe exacerbations during the study. Patients with severe exacerbations had a greater annual decline in FEV1 compared to patients with no exacerbations (-13.6 vs. -53.2 mL yr(-1), p < 0.0001).

Among patients with controlled asthma at baseline, the rate of change in FEV1 is highly variable. Severe exacerbations are strongly associated with a rapid loss of lung function.