Hallas HW, Chawes BLK, Arianto L, et al. - Researchers compared asthmatic children with and without exacerbations with respect to lung function trajectories from birth till adolescence. Repeat evaluations of lung function and bronchial reactivity were performed from 1mo to 13yrs in children with asthma from the Copenhagen Prospective Studies on Asthma in Childhood₂₀₀₀ (COPSAC₂₀₀₀) birth cohort. At the COPSAC clinic, exacerbations (defined as symptoms needing hospitalization, oral or high-dose inhaled corticosteroid treatment) were diagnosed. Since infancy through childhood, increased airway obstruction was seen in children with asthma with exacerbations vs asthma children without exacerbations. The airway obstruction represents a fixed trajectory without progression because of exacerbations, indicating that exacerbations are a result rather than a cause of diminished airway caliber in childhood.