Exhaled nitric oxide and bronchial hyperresponsiveness in atopic asthmatic children with and without allergic rhinitis

ABSTRACT

PURPOSE: Children with asthma frequently have allergic rhinitis (AR) as a comorbidity. Asthmatic children with AR have a higher exhaled nitric oxide (eNO) level and bronchial hyperresponsiveness (BHR) than those without. The purpose of this study is to investigate the difference in lung function, eNO, and BHR between atopic asthma with and without AR, and the association of eNO and BHR with atopic intensity in total asthmatics. METHODS: We recruited 69 atopic asthmatic children with AR, 19 atopic asthmatic children without AR, 38 children with AR, and 43 nonatopic controls. We measured forced expiratory volume in one second (FEV1) and forced expiratory flow at 25% to 75% of forced vital capacity (FEF(25%-75%)), dose response slope (DRS) of bronchial challenge with methacholine and adenosine 5'-monophosphate (AMP), the levels of eNO, and the ratio of sum of allergen wheal diameter to histamine using skin prick tests. RESULTS: Atopic asthmatic children with AR had a higher eNO level compared to those without AR (P<0.05). However, there was no difference in FEV1 %predicted, FEF(25%-75%) %predicted, methacholine DRS, and AMP DRS between asthmatic children with and without AR. In total asthmatics, methacholine DRS and AMP DRS significantly correlated with eNO levels (r=0.338, P<0.001; r=0.365, P<0.001), but not with total IgE levels. However, eNO significantly correlated with total IgE levels (r=0.479, P<0.001). CONCLUSION: These results suggest that AR may enhance airway inflammation but may not lead to enhanced BHR in children with asthma.