Long‐Term, Real‐World Effectiveness of Allergen Immunotherapy in Children and Adolescents With Allergic Rhinitis and Asthma

Background Respiratory allergies often begin in childhood and can progress over time, leading to increased disease burden. Allergen immunotherapy (AIT) is the only causal treatment for allergic respiratory diseases with disease‐modifying potential. While randomised trials support its efficacy in controlling allergic rhinitis (AR) and asthma symptoms, long‐term real‐world data in children remain limited. Methods This paediatric study ( n = 11,036) was conducted within the pre‐defined framework of the REACT study, based on protocol‐specified objectives. Children (< 18 years) with physician‐diagnosed AR, with or without pre‐existing asthma, were included. AIT‐treated patients were matched 1:1 to non‐AIT controls. Effectiveness was assessed over 9 years by comparing AR and asthma medication prescriptions, using a public database covering all reimbursable AIT products. Relative differences were calculated across the full observation period. Results AIT‐treated children (mean age 11.4 years; 62.1% male) exhibited greater reductions in AR medication use than controls (additional 9% reduction beyond 61% in controls). In children with asthma, AIT was associated with additional reductions in asthma medication use (−21% beyond −48% in controls), severe exacerbations (−21% beyond −36%), and new oral corticosteroid prescriptions (−33% beyond −41%). Age stratification revealed more pronounced AR medication reductions in younger children (0–11 years) than in adolescents (12–17 years). Conclusion This large‐scale, real‐world study supports the long‐term effectiveness of AIT in children with AR, with or without asthma. The findings reflect improved disease control and suggest a disease‐modifying effect of AIT. Early intervention, particularly in younger children, may help mitigate the progression of allergic disease.