Crucial Factors for Bronchial Hyperresponsiveness in Children with Mild Asthma

Chang, Ji Young; Shin, Su A; Oh, Jae Won; Lee, Ha Baik

Abstract

PURPOSE
Bronchial hyperresponsiveness (BHR) is one of the key components of childhood asthma phenotype. Patients with mild asthma may have coexisting severe BHR, although the reasons for this are uncertain. The factors of any relationship between BHR has been identified as a central issue in our understanding of asthma. METHODS: To investigate the factors that determine the presence of BHR in mild childhood asthmatics, 62 children (49 boys and 13 girls) with mild asthma were studied. Patients were characterized by skin prick tests, spirometry and bronchial challenge with methacholine. BHR to methacholine was expressed as the provocative methacholine concentration causing a 20 percent fall in FEV1 (PC20), PC20 value of 8 mg/mL was used as a cut-off for defining a BHR to methacholine. RESULTS: This cohort of 62 children with mild asthma was classified into two groups according to the results of methacholine challenge test (MCT). A positive MCT group was obtained for 33 subjects (53.2 percent). The proportion of children sensitized to house-dust mites (HDM) was significantly higher in the MCT-positive group than the negative one. Results showed a, a positive rate of skin prick test: 47% vs. 23% (P< 0.05) and HDM-specific IgE: 68% vs. 43% (P< 0.05). CONCLUSION: Asthmatics with positive MCT were clearly accompanied by increased sensitization to house-dust mites and reduced small airway calibers. Therefore, sensitization to common aeroallergens and changed small airway calibers might be crucial factors in the successful management of asthma.