Factors associated with exhaled nitric oxide in children with asthma and allergic rhinitis.

Background: Factors attributable to the level of fraction of exhaled nitric oxide (FeNO) in different age groups of asthmatic children are still lack of report. Objective: To evaluate factors associated with FeNO and the response of FeNO to inhaled steroid in different age groups of asthmatic children with allergic rhinitis. Methods: Asthmatic children aged 5 to 12 years were recruited. FeNO, lung function and bronchial hyperresponsiveness (BHR) to methacholine, skin prick testing to a panel of aeroallergens, total immunoglobulin E (T‐IgE) in serum and eosinophils in blood were tested. Correlations between FeNO and the measured parameters were assessed. FeNO was measured again after the treatment of combined inhaled corticosteroid and long‐acting beta‐agonist (ICS/LABA) for 4 weeks. Changes in FeNO between different age groups were compared. Results: A total of 121 eligible subjects were enrolled in and completed this study. Asthmatic children aged 10 to 12 years old had significantly higher FeNO than those between 8 and 9 years and 5 to 7 years of children (both P < 0.01). Greater height/age (P < 0.01) and higher level of total allergen IgE (P < 0.01) are associated with a higher value of FeNO. After 4 weeks of treatment with ICS/LABA, asthma control test scores were significantly increased in all age groups (P < 0.01), while the level of FeNO significantly decreased in the elder age group only (P < 0.01). Conclusions: Height and T‐IgE are well correlated with FeNO in asthmatic children aged 5 to 12 years. Measurement of FeNO is more suitable for evaluating the efficacy of ICS/LABA in elder asthmatic children. [ABSTRACT FROM AUTHOR]