Difference in Airway Reactivity in Children With Atopic vs Nonatopic Asthma

Study objective: To examine the difference in the mechanisms of bronchial hyperresponsiveness (BHR) in nonatopic asthma and in atopic asthma, we studied bronchial reactivity against nonspecific stimuli in children with atopic asthma and nonatopic asthma. Design and participants: Fourteen children with nonatopic asthma, 24 children with atopic asthma, and 20 age-matched controls participated in this study. Measurements: Inhalation challenge was performed by administering progressively doubling doses of methacholine with a continuous inhalation provocation method. The speed of bronchoconstriction to methacholine (Sm) and the speed of reversal of bronchoconstriction to methacholine after inhalation of a b2-agonist (r-Sm), which was considered to represent the effect of the b2-agonist, were calculated from the dose-response curve. Results: The value of Sm was higher in the nonatopic asthma group than in the atopic asthma group and the control group. The value of r-Sm was also higher in the nonatopic asthma group than in the atopic asthma group, but did not differ from that in the control group. Conclusion: These results indicate that bronchial reactivity against methacholine and the b2-agonist was greater in nonatopic asthma than in atopic asthma, and that the mechanism of BHR in children with nonatopic asthma may differ from that in children with atopic asthma. (CHEST 1999; 116:619 ‐ 624)