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

Differentiating severe asthma by age at onset and presence or absence of eosinophils identifies phenotypes of asthma, which could benefit subsequent genetic and therapeutic studies.