Background: Subjects with allergic rhinitis but no clinical evidence of asthma have greater bronchial hyperresponsiveness (BHR), and several factors have been implicated as its determinants. However, studies in young children are lacking. The aims of this study were to evaluate the prevalence of BHR in young children with allergic rhinitis and to investigate its risk factors.
Methods: Methacholine bronchial challenges were performed in 4- to 6-year-old nonasthmatic children with allergic rhinitis (n = 83) and in healthy nonatopic controls (n = 32), using a modified auscultation method. The end-point was defined as the appearance of wheezing and/or oxygen desaturation. Subjects were considered to have BHR when they had end-point concentrations of methacholine <or=8 mg/mL. Clinical and laboratory data in allergic rhinitis patients and a history of allergic diseases in their parents were collected.
Results: BHR was observed in 27 subjects with allergic rhinitis (32.5%) and three controls (9.4%). Among subjects with allergic rhinitis, serum total IgE, the number and pattern of skin-prick test responses, blood eosinophil markers, and parental history of allergic rhinitis and atopic dermatitis were not different between the BHR(+) and BHR(-) groups, whereas the persistent type of rhinitis and parental history of asthma were more frequent in the BHR(+) group than in the BHR(-) group. These associations remained significant in a multivariable logistic regression.
Conclusions: Young children with allergic rhinitis alone showed an increased prevalence of BHR. Both persistent type of rhinitis and parental history of asthma were significant and independent risk factors for BHR in these children.