Background: Eosinophilic airway inflammation is a key pathophysiological feature of asthma that can predict treatment response. However, the prognostic value of sputum eosinophilia is not established.
Objective: The aim of this study was to determine the influence of induced sputum eosinophilia on the prognosis of childhood asthma.
Methods: A cohort of children with asthma was evaluated by induced sputum analysis at inception and classified as having either eosinophilic asthma (EA) (sputum eosinophils >2.5%) or non-eosinophilic asthma (NEA). After a mean follow-up period of 5 years, eligible subjects (n=83) were contacted and 69 subjects (33 EA, 36 NEA) evaluated. The children had a mean age of 15.9 years, and 61% were male.
Results: Children with EA reported more wheeze during the follow-up period (27% vs. 6% wheezed most years; P<0.0001), increased night waking during the past 12 months (28% vs. 3% reported weekly waking; P=0.01), and greater impairment of quality of life due to asthma (P=0.04). Subsequent beta2-agonist use was increased in children with EA (P=0.02), although there was no difference in corticosteroid use. In EA, subsequent forced expiratory volume in 1 s/forced vital capacity was lower (79% vs. 86%; P=0.01) and grass pollen allergy was more prevalent (77% vs. 27%; P=0.006).
Conclusion: In children, eosinophilic airway inflammation is associated with deteriorating asthma over time. This is consistent with the hypothesis that airway inflammation has an adverse impact on the prognosis of childhood asthma, and suggests a role for monitoring inflammation in asthma management.