Maximal Airway Response in Adolescents With Long-term Asthma Remission and Persisting Airway Hypersensitivity: Symptomatic asthma
Another major finding of this study was that inhaled budesonide did not cause a significant reduction in the level of the maximal response plateau in adolescents with asthma remission. However, inhaled budesonide was observed to reduce it in patients with symptomatic asthma, in accordance with previous studies.- This is the first study to evaluate the effects of inhaled corticosteroids on the level of maximal airway response to inhaled methacholine, among symptom-free asthmatic adolescents with persistent BHR. A randomized placebo-controlled design enabled the examination of the longitudinal changes in maximal response during adolescence. Although some fluctuations occurred in individual subjects, a small but nonsignificant improvement was observed in the placebo/remission group. A similar trend was observed in the budesonide/remission group, and there was no significant difference in these observed changes between the two groups, It is unlikely that the potential for reduction was limited by confounding factors, such as allergen exposure, or viral respiratory infections, since the methacholine challenges were timed to avoid the peak house dust mite season and were not performed within 4 weeks of viral respiratory infection. The absence of significant improvement with corticosteroid treatment might be attributable to inadequate budesonide dosing or duration. However, this is also unlikely, since the same treatment regimen significantly reduced the maximal response in the budesonide/symptomatic group. Meanwhile, another study has demonstrated a marked effect with the same dose of budesonide and over a period as short as 4 weeks in patients with symptomatic asthma. Other factors that might have reduced the effect of budes-onide include insufficient bioavailability of the drug, poor patient compliance with therapy, and relatively mild degree of maximal response in our subjects. Because we used the novel multiple-dose dry-powder inhaler, insufficient bioavailability of budesonide seems unlikely. Following a careful check of the degree of compliance with the recommended use of budesonide, the subjects with poor compliance were excluded. Finally, it can be argued that the potential benefits of inhaled budesonide on the maximal airway response may be more evident in subjects with unlimited airway narrowing, rather than in those with maximal response plateau. However, the selection of subjects with maximal response plateau was necessary to allow estimation of change in repeated measurements.