Factors influencing symptom expression in children with bronchial hyperresponsiveness at 10 years of age

Objectives: We sought to identify factors associated with wheezing symptoms in children found to have bronchial hyperresponsiveness (BHR) at 10 years of age. Methods: Children were seen at birth, 1, 2, 4 and 10 years of age in an entire population birth cohort study (n = 1456). At each stage information was collected prospectively on genetic and environmental risk factors for BHR. Skin prick testing was performed at 4 and 10 years of age. Spirometry and methacholine bronchial challenge were conducted at 10 years of age when BHR was considered present If PC20 FEV1 was < 4.0 mg/mL. In children with BHR at 10 years of age, factors independently associated with current wheezing were determined by logistic regression. Results: BHR was identified in 169 10-year-olds at bronchial challenge, 55.6% of whom manifested current wheeze. In children with BHR, current wheezers had higher Log(10) total IgE and greater BHR than those who had never wheezed. Symptomatic BHR was independently associated with atopic sensitization (P < .001) and maternal asthma (P = .011) at 10 years of age. If only factors present in the first 4 years of life were considered, parental smoking at 4 years of age (P = .021), maternal asthma (P = .017), and atopic sensitization at 4 years of age (P = .004) were independently associated with symptomatic BHR at 10 years of age. Conclusions: Symptomatic BHR is associated with greater degrees of BHR and higher total IgE. Heredity, atopy, and environmental exposure might influence symptom expression in children with BHR.