Background: Allergic rhinitis (AR) is increasingly recognized as a systemic airway disease that may involve the lower respiratory tract even in the absence of overt asthma symptoms. Impulse oscillometry (IOS) is a sensitive and noninvasive method for detecting peripheral airway dysfunction in children. This cross-sectional study aimed to characterize peripheral airway function in non-asthmatic children with moderate-to-severe persistent allergic rhinitis during the early phase of allergen immunotherapy using impulse oscillometry. Methods: This cross-sectional case–control study included 69 children with moderate-to-severe persistent allergic rhinitis and 65 age- and sex-matched healthy controls. All patients had grass pollen sensitization and were receiving subcutaneous allergen immunotherapy. Children with clinical asthma symptoms, abnormal baseline spirometry, or chronic pulmonary disease were excluded. IOS parameters including R5, R20, R5–R20, X5, AX, and Fres were measured and compared between groups. Results: Demographic and anthropometric characteristics were similar between the groups. The allergic rhinitis group demonstrated significantly higher R5 values [0.41 (0.20) vs. 0.37 (0.18) kPa·L⁻¹ s, p = 0.019], R5–R20 values [0.140 (0.13) vs. 0.10 (0.08) kPa·L⁻¹ s, p = 0.001], and AX values [1.05 (1.14) vs. 0.86 (0.61) kPa·L⁻¹, p = 0.035] compared with healthy controls. No significant differences were observed in R20, X5, X20, or Fres parameters. Conclusions: Children with moderate-to-severe persistent allergic rhinitis may exhibit subclinical small airway dysfunction despite the absence of asthma symptoms. IOS appears to be a useful tool for detecting early peripheral airway involvement and may help identify children at increased risk for future asthma development.

Comment on the article ‘Burden and risk of asthma and rhinitis in people with atopic dermatitis: global estimates from a hierarchical Bayesian model’ by Liu et al.