D2.57 - Evidence of Lower Airway Inflammation in Children with Allergic Rhinitis without Asthma

The concept of “one airway, one disease” suggests that the upper and lower airways constitute a single continuous inflammatory pathway. Despite this, population-based evidence regarding the presence of lower airway inflammation in children with allergic rhinitis but without asthma remains limited.

A cross-sectional study was conducted in a community-based paediatric cohort comprising 71 classrooms from 20 public schools in the city of Porto, Portugal, during 2014. Children underwent clinical assessment, measurement of fractional exhaled nitric oxide (FeNO), and spirometry. Current allergic rhinitis was identified by self-reported medical diagnosis. Children with physician-diagnosed asthma were excluded. FeNO and lung function parameters were compared between children with and without current allergic rhinitis. Given the non-normal distribution of FeNO, results are presented as median (interquartile range, IQR) and compared using non-parametric tests. Spirometric parameters were analysed descriptively and compared between groups.

Among children without asthma (n = 559), 84 (15%) had current allergic rhinitis and 475 (85%) had no rhinitis. Children with allergic rhinitis exhibited significantly higher FeNO levels compared with their non-rhinitic peers (median 15 ppb [IQR 7–37.50] vs 10 ppb [IQR 6–16], p = 0.0001), indicating increased eosinophilic inflammation in the lower airways. In contrast, lung function did not differ meaningfully between groups. Median pre-bronchodilator FEV₁ was 1.80 L (IQR 1.65–1.95) in children with rhinitis and 1.74 L (IQR 1.58–1.96) in those without (p = 0.131), while median post-bronchodilator FEV₁ was 1.88 L (IQR 1.70–2.06) in children with rhinitis and 1.82 L (IQR 1.63–2.00) in those without (p = 0.120). Similar findings were observed for FVC and peak expiratory flow, all of which remained within normal ranges and showed no statistically significant differences.

Among children without asthma, allergic rhinitis is associated with increased lower airway eosinophilic inflammation, as evidenced by higher FeNO levels, despite preserved lung function in both groups. These results provide population-based evidence supporting the “one airway, one disease” paradigm by demonstrating that allergic rhinitis in childhood is associated with lower airway inflammation even in the absence of asthma. These findings highlight the importance of integrated assessment of the upper and lower airways in paediatric allergic respiratory disease.