Exhaled nitric oxide measures allergy not symptoms in children with allergic rhinitis in primary care: a prospective cross-sectional and longitudinal cohort study.

Background: Allergic rhinitis (AR) and asthma are both inflammatory diseases and are often associated. Relationships between fractional exhaled nitric oxide (FeNO) and asthma, atopy, and quality of life have been shown.

Aims: This study aimed to determine whether FeNO in children with AR (n=158) or combined AR and asthma (n=93) was associated with clinical symptoms, house dust mite (HDM)-specific IgE, and rhinitis-specific quality of life, both cross-sectionally and longitudinally.

Methods: Children with AR aged 6-18 years (n=251) in primary care were assessed for FeNO, nasal symptom scores, asthma symptom scores, quality of life, and HDM-specific IgE at baseline and 2 years later.

Results: We found similarly elevated FeNO in children with only AR and in those with combined AR and asthma. No correlations were found between FeNO and nasal or asthma symptoms and rhinitis-related quality of life. Longitudinal correlations were strongest for HDM-specific IgE (r=0.91, p<0.0001).

Conclusions: FeNO was similar in a selected group of children with AR with and without asthma in primary care and was unrelated to symptoms or quality of life in both groups. FeNO is unlikely to be a useful biomarker of the clinical severity of upper or lower airway disease in primary care.