The prevalence of bronchial hyperresponsiveness in elementary school children and its associated factors

ABSTRACT

PURPOSE: We investigated the prevalence of bronchial hyperresponsiveness (BHR) and its associated factors in population-based elementary school children. METHODS: Methacholine bronchial provocation tests were performed on 1,151 elementary school children and BHR was defined as PC20 (provocative concentration of methacholine causing a 20% fall in forced expiratory volume in 1 second [FEV1]) or =25 ppb (aOR, 2.118; P=0.025), and sensitization to mites (aOR, 1.705; P=0.034) were associated with BHR. Preterm birth (aOR, 2.056; P=0.068) showed borderline significance. The associated factors for BHR with atopy were lower body mass index (aOR, 0.838; P=0.005), preterm birth (aOR, 4.361; P=0.003), and FeNO > or =25 ppb (aOR, 2.161; P=0.043). Younger age (aOR, 0.810; P=0.037) and higher blood eosinophil % (aOR, 1.296; P<0.001) were associated with BHR without atopy. CONCLUSION: The prevalence of BHR decreased with age in elementary school children. Younger age, preterm birth, eosinophilia, sensitization to mites, lower lung function, and higher FeNO level were independently associated with BHR.