Asthma with allergic comorbidities in adolescence is associated with bronchial responsiveness and airways inflammation.

BACKGROUND: Childhood asthma frequently has allergic comorbidities. However, there is limited knowledge of the longitudinal development of asthma comorbidites and their association to bronchial hyper-responsiveness (BHR) and airway inflammation markers. We therefore aimed to assess the association between childhood asthma with allergic comorbidities and BHR and fractional exhaled nitric oxide (FE(NO)) and the impact of gender on these associations.

METHODS: Based on data from 550 adolescents in the prospective birth cohort 'Environment and Childhood Asthma' study, asthma was defined for the three time periods 0-2, 2-10 and 10-16 years of age, using recurrent bronchial obstruction (rBO) 0-2 years of age as a proxy for early asthma. Asthma comorbidities included atopic dermatitis (AD) and allergic rhinitis (AR) from 10 to 16 years. At age 16 years BHR, assessed by metacholine bronchial challenge, and airway inflammation, assessed by FE(NO), were compared between the groups of asthma with or without the two comorbidities, to a reference group with no never asthma, and subsequently stratified by gender.

RESULTS: Boys with asthma and AR, regardless of AD had significantly more severe BHR and higher FE(NO) than the other asthma phenotypes. Almost half of the children remained in the asthma and AR category from 10 to 16 years, the entire difference being determined by new incident cases from 10 to 16 years.

CONCLUSIONS: Asthma phenotypes characterized by allergic comorbidities and AR in particular appears closely associated with BHR and FE(NO), especially among boys.