Maximal Airway Response in Adolescents With Long-term Asthma Remission and Persisting Airway Hypersensitivity: Discussion
All subjects in the budesonide/ symptomatic group attained a maximal response plateau on the dose-response curve to methacholine during the treatment period. In this group, inhaled budesonide markedly decreased the maximal response plateau from the baseline value (42.9 ± 3.7%) to 35.4 ± 5.0% and 33.7 ± 6.1% at 3 months and 6 months of treatment, respectively (both p < 0.01).
This study has shown that the levels of maximal airway response on the dose-response curves to methacholine were significantly lower in adolescents with asthma remission than in symptomatic asthmatic adolescents with a similar degree of airway hypersensitivity. Maximal airway responses in adolescents with asthma remission were not reduced by regular treatment with inhaled corticosteroids, in contrast to the reduction that did occur in adolescents with symptomatic asthma.
In normal subjects, the dose-response curve achieves a plateau at mild degrees of airway narrowing, whereas in asthmatic subjects increasing doses of inhaled pharmacologic agents usually lead to progressive airway narrowing without the achievement of a plateau response. We have found that adolescents with asthma remission had a higher frequency of plateau on the dose-response curves to methacholine than adolescents with symptomatic asthma to a similar degree of airway sensitivity to methacholine. It is arguable that some subjects who had FEV1 falls of > 50% without evidence of plateau might present a plateau beyond a 50% fall from baseline FEV1. However, we do not believe that this factor had predilection for the group of adolescents with symptomatic asthma. Furthermore, the level of maximal airway response was significantly lower in adolescents with asthma remission than in those with symptomatic asthma, despite a possible underestimation of the difference between the two groups resulting from the more frequent inclusion of subjects without a plateau in the latter group.