Cost-Effectiveness of Allergen Immunotherapy for Allergic Rhinitis: A Systematic Review

Allergic rhinitis imposes a substantial clinical and socioeconomic burden globally. While symptomatic pharmacotherapy such as oral antihistamines and intranasal corticosteroids offers temporary relief, allergen immunotherapy provides disease-modifying benefits but requires higher upfront costs. This systematic review synthesises cost-effectiveness evaluations of subcutaneous (SCIT) and sublingual immunotherapy (SLIT) compared to symptomatic pharmacotherapy (SP). A systematic search of electronic databases was undertaken, identifying 35 eligible economic evaluations. Due to methodological heterogeneity, a narrative synthesis was performed. Thirty-two evaluations (91%) concluded that allergen immunotherapy represents a cost-effective intervention, with incremental cost-effectiveness ratios predominantly falling below jurisdictional willingness-to-pay thresholds. Both SCIT and SLIT demonstrated economic value, particularly in patients with co-morbid asthma and when models incorporated sustained post-treatment benefits. Future clinical research should prioritise endpoints that facilitate direct estimation of health utility. Despite diverse healthcare settings and modelling approaches, the evidence supports allergen immunotherapy (AIT) as an economically rational investment. Policymakers should utilise these findings to inform reimbursement decisions. Trial Registration: PROSPERO registration number: CRD42024530911.