Real-world benefits of allergen immunotherapy for birch pollen-associated allergic rhinitis and asthma

Background: Real-world evidence is sparse on the benefits of allergen immunotherapy [AIT; subcutaneous/sublingual immunotherapy (SCIT/SLIT)], the only disease-modifying intervention for allergic rhinitis (AR) with long-term efficacy. This real-life study evaluated the effect of six AITs (native pollen SLIT/SCIT, four allergoid SCITs) vs symptomatic medication use, on AR symptoms and asthma symptoms/onset, in patients with birch pollen-associated AR and/or asthma.

Methods: In this retrospective cohort analysis of a German longitudinal prescription database, AIT patients received ≥2 successive seasonal treatment cycles; non-AIT patients had ≥3 AR prescriptions in three seasons or previous month. Patients were matched for: index year, age, gender, main indication at index, number of seasonal cycles within treatment period, baseline AR/asthma treatment prescriptions. Multiple regression analysis compared prescription data in AIT and non-AIT groups as proxy for clinical status/disease progression.

Results: Up to 6 years of follow-up, significantly more AIT (65.4%) vs non-AIT (47.4%) patients were AR medication-free; odds ratio (OR) [95% confidence interval (CI)]: 0.51 [(0.48-0.54); P < 0.001] (28.6% covariate-adjusted reduction vs non-AIT; P < 0.001), and significantly more AIT (49.1%) vs non-AIT (35.1%) patients were asthma medication-free [OR (95% CI): 0.59 (0.55-0.65); P < 0.001] (32% reduction vs non-AIT; P < 0.001), or reduced existing asthma medication use (32% covariate-adjusted reduction vs non-AIT; P < 0.001). During treatment, new-onset asthma risk was significantly reduced in the AIT vs non-AIT group (OR: 0.83; P = 0.001).

Conclusions: Birch pollen AIT demonstrated real-world benefits up to 6 years post-treatment cessation through significantly reduced AR and asthma medication intake, and significantly decreased risk of new-onset asthma medication use on-treatment.