Bronchial hyperresponsiveness in preschool children with allergic rhinitis.

BACKGROUND: Nonasthmatic subjects with allergic rhinitis often have bronchial hyperresponsiveness (BHR), characteristic of asthma. The presence and degree of atopy is suggested to be important for BHR in patients with asthma. We aimed to assess BHR to methacholine (direct stimulus) and to adenosine 5'-monophosphate (AMP; indirect stimulus) in preschool children with allergic rhinitis and to investigate their relationship with the degree of atopy. METHODS: Methacholine and AMP bronchial challenges were performed in preschool children with allergic rhinitis (n = 96), using a modified auscultation method. The end point concentration, resulting in audible wheezing and/or oxygen desaturation, was determined for each challenge. The degree of atopy was assessed using serum total IgE levels, the number of positive skin-prick tests, and atopic scores (sum of graded wheal size). RESULTS: BHR to methacholine (end point concentration, ≤8 mg/mL) and to AMP (end point concentration, ≤200 mg/mL) was observed in 32 (33.3%) and 26 (27.1%) subjects, respectively. No significant relationship was observed between BHR to methacholine and any atopy parameter. In contrast, the atopic scores were higher in the AMP-BHR(+) group compared with the AMP-BHR(-) group, and a significant association was found between the degree of atopic scores and the frequency of BHR to AMP (score for trend, p = 0.006). Such a relationship was not observed for serum total IgE levels and the number of positive SPTs. CONCLUSION: BHR to methacholine and BHR to AMP were detected in a significant proportion of preschool children with allergic rhinitis. The degree of atopy in terms of atopic scores seems to be an important factor for BHR to AMP but not for BHR to methacholine.