Objective: Fractional exhaled nitric oxide (FeNO) is a non-invasive biomarker of airway inflammation. Our aim was to analyze the interrelationship and differentiate the predicting effects of asthma, allergic rhinitis (AR), and atopic dermatitis (AD) on the FeNO levels in children from mainland China.
Methods: A case-control study with age- and gender matched 1:1 was designed based on a larger cross-sectional survey on asthma, AR, and AD in Shanghai. A self-administered questionnaire was used to collect information on children's health information. Children with positive reports on physician-diagnosed asthma and/or AR and/or AD were recruited as cases, and children with no report of any of the diseases were designated as controls. The FeNO measurement was performed online, using the NIOX MINO® instrument (Aerocrine AB, Solna, Sweden) at 50 ml/min.
Results: A total of 130 subjects (65 cases and 65 controls, average age = 10 years) were recruited in this study. The average FeNO level was significantly higher in the cases (29.8 ± 1.9 ppb) than that in the controls (13.3 ± 1.7 ppb) (p < .001). Using multiple linear regression analysis controlling for confounding factors, including parental asthma/allergic diseases and home exposure, asthma (β = 0.330, p < .001) and AR (β = 0.157, p = .006) showed significant predicting effects for high FeNO levels, whereas AD was not related to the FeNO levels.
Conclusions: Both asthma and AR could independently increase the FeNO levels in Chinese schoolchildren. Other diseases besides asthma should be considered when applying FeNO as a screening tool for asthma in Chinese children.