Contributions of asthma, rhinitis and IgE to exhaled nitric oxide in adolescents

Exhaled nitric oxide fraction (FeNO) is an indicator of allergic airway inflammation. However, it is unknown how asthma, allergic rhinitis (AR) and allergic sensitisation relate to FeNO, particularly among adolescents and in overlapping conditions. We sought to determine the associations between asthma, AR, and aeroallergen immunoglobulin (Ig)E and FeNO in adolescents. We measured FeNO among 929 adolescents (aged 11–16 years) in Project Viva, an unselected prebirth cohort in Massachusetts, USA. We defined asthma as ever asthma physician diagnosis plus wheezing in the past year or taking asthma medications in the past month, AR as a physician diagnosis of hay fever or AR, and aeroallergen IgE as any IgE >0.35 IU·mL−1 among 592 participants who provided blood samples. We examined associations of asthma, AR and IgE with percent difference in FeNO in linear regression models adjusted for sex, race/ethnicity, age and height, maternal education and smoking during pregnancy, and household/neighbourhood demographics. Asthma (14%) was associated with 97% higher FeNO (95% CI 70–128%), AR (21%) with 45% higher FeNO (95% CI 28–65%), and aeroallergen IgE (58%) with 102% higher FeNO (95% CI 80–126%) compared to those without each condition, respectively. In the absence of asthma or AR, aeroallergen IgE was associated with 75% higher FeNO (95% CI 52–101), while asthma and AR were not associated with FeNO in the absence of IgE. The link between asthma and AR with FeNO is limited to those with IgE-mediated phenotypes. FeNO may be elevated in those with allergic sensitisation alone, even in the absence of asthma or AR