Relationship between airway hyperresponsiveness and duration of asthma in children

Shin, Su A; Oh, Jae Won; Kim, Nam Su; Lee, Ha Baik

Abstract

BACKGROUND
Asthma is a chronic inflammatory disease. Clinical symptoms of asthmatics are triggered by various factors associated with allergic inflammation, airway remodeling and bronchial hyperreactivity, which were frequently related to the duration of asthma history. OBJECTIVES: To investigate the relationships between bronchial hyper-responsiveness and asthma duration thirty-five mild-to-moderate stable asthmatic children (28 boys and 7 girls), aged 6 to 18 years participated in this study. METHODS: By using cross-sectional analysis of data on variables as asthma duration, spiro-metry, results of bronchial responsiveness, symptomatology, and markers of atopy, univarate regression models were used to evaluate whether asthma duration was associated with asthma severity. Bronchial hyperresponsiveness to methacholine was expressed as provocative concentration of methacholine causing a 20% fall in FEV(1)[PC(20)mg/ml]. Exercise challenge consists of free outdoor running for 6 to 8 min at 80% of maximal predicted heart rate for age and a fall of 20% in FEV(1) associated with wheezing or cough was considered as positive. RESULTS: In all subjects methacholine and exercise challenge tests were performed, twenty-five children had atopic asthma(71.4%). Positive challenge tests were observed in 24 patients(68.6%) for methachol, 18(51.4%) for exercise, and 18(51.4%) for both, exercise in 18(51.4%) and both in 18(51.4%) of the 35 asthmatic children, respectively. In this cohort, the decrease of %FEV(1)/FVC was well correlated with the duration of asthma history. There was a significant relationship between %FEV(1)/FVC and %PEFR, %FEV(1), %FEF(25), %FEF(50), %FEF(75) or %MMEF(75/25). CONCLUSION: These data demonstrate that asthma duration is relevantly associated with lower lung function and greater responsiveness to both methacholine and exercise. Consequently, early intervention in childhood asthma management is definitely required.