Childhood fractional exhaled nitric oxide as a predictor of asthma symptoms in adolescence

[[abstract]]Background : Asthma is a common disease in pediatric populations. It affects approximately 350 million people worldwide. Fraction of exhaled nitric oxide (FeNO) is recognized as a clinical marker of airway inflammation. However, it remains unclear whether childhood FeNO levels can be served as a predictor of subsequent asthma symptoms in adolescence. This study aims to investigate the relationship between childhood FeNO levels and subsequent asthma symptoms in adolescence. Method : The study children were enrolled from the Prediction of Allergies in Taiwanese CHildren (PATCH) study, a prospective population- based cohort study launched in 2007. We measured FeNO level of each participant using a single- breath online method at enrollment, and employed a modified International Study of Asthma and Allergies in Childhood (ISAAC) questionnaire to collect demographic data, general health information, and clinical data (e.g., clinical symptoms and diagnosis of allergic diseases) at enrollment and the 6- year follow- up, respectively. Multiple logistic regression models with covariates adjustment were carried out to evaluate the association of between childhood FeNO levels and longitudinal change of asthma symptoms in adolescence. Results : A total of 1210 study children were included. Among those, there were 54 (4.5%) children without physician- diagnosed asthma at enrollment, but with physician- diagnosed asthma at follow- up, defined as incidence of physician- diagnosed asthma; 113 (9.3%) children with physician- diagnosed asthma at both enrollment and follow- up, defined as persistence of physician- diagnosed asthma; and 165 (13.6%) children with physician- diagnosed asthma at enrollment, but without physician- diagnosed asthma at follow- up, defined as remission of physician- diagnosed asthma. There were positive associations between FeNO levels at enrollment and longitudinal change of asthma symptoms at follow- up (adjusted odds ratio (AOR) = 2.33, 95% confidence interval (CI):1.82- 2.99 for wheeze ever; AOR = 2.39, 95%CI:1.60- 3.56 for current wheeze; and AOR = 2.16, 95%CI:1.65- 2.84 for physician- diagnosed asthma). Positive associations between FeNO levels at enrollment and persistent asthma symptoms at follow- up, including wheeze ever (AOR = 1.82; 95%CI:1.23- 2.70), current wheeze (AOR = 2.30; 95%CI:1.06- 4.98) and physician- diagnosed asthma (AOR = 1.73; 95%CI:1.01- 2.96) were also observed