Usefulness of exhaled nitric oxide in newborns to predict asthma at school age

Abstract

Background: Fraction of exhaled nitric oxide (FeNO) is a biomarker of airway inflammation. Elevated FeNO measured in high-risk populations during early childhood is associated with school age asthma. It is unknown if assessment of FeNO shortly after birth is associated with asthma. Aim: We aimed to identify if postnatal, premorbid assessment of FeNO prior to viral infections is associated with asthma diagnosis at school age. Methods: In a population-based birth cohort, FeNO was measured in healthy term infants aged 5 weeks during quiet tidal breathing in unsedated sleep. At the follow-up with 6 years, we assessed the asthma and atopy diagnoses and a skin prick test (SPT) was performed. Associations between FeNO and diagnosis of asthma, atopy and positive (SPT) were calculated using regression analysis. Results: From 234 enrolled infants, 208 (89%) were followed-up until 6 years. FeNO at infancy was not associated with asthma (n=27), atopy (n=62) or positive SPT (n=26) at the age of 6 years. Per 1 ppb increase, the odds ratio (95% CI) for asthma was 0.96 (0.89–1.05), atopy 0.99 (0.94–1.05) and positive SPT 0.95 (0.88–1.03). Associations were not modified by assessed risk factors (sex, parental atopy, parental asthma and smoking during pregnancy). Conclusions: In this cohort of unselected healthy infants, FeNO from newborns was not associated with diagnoses of asthma or atopy at school age. We speculate that alterations in nitric oxide metabolism may occur during infancy, under conditions that should be further investigated.