Distinguishing severe asthma phenotypes☆Role of age at onset and eosinophilic inflammation

Asthma is a heterogeneous process, yet little is understood regarding phenotypes.To determine whether phenotypic differences exist between early-onset, severe asthma as compared with late-onset disease and whether the presence or absence of eosinophilia influences the phenotypes.Cross-sectional analysis of integrated clinical, physiologic, and pathologic data collected from 80 subjects with severe asthma. Subjects were divided into those with asthma onset before age 12 years (n = 50) versus after age 12 (n = 30) and by the presence or absence of lung eosinophils.Subjects with early-onset, severe asthma had significantly more allergen sensitivity (skin test positivity, 98% vs 76%, P <.007) and more allergic symptoms (P values all