Safety and Effectiveness of Allergen Immunotherapy in Patients with Severe Allergic Asthma.

Objective: Allergen immunotherapy (AIT) is an established treatment for mild to moderate allergic asthma. However, limited data are available regarding its safety and efficacy in patients with severe asthma. This study aimed to gather real-world evidence (RWE) on the safety and effectiveness of AIT in individuals with severe asthma caused by sensitization to at least 1 allergen, who were either currently undergoing AIT or had received it within the past five years. Methods: A retrospective study was conducted in Spain, including patients aged ≥6 years with severe asthma (Spanish Guideline for Asthma Management [GEMA] steps 5-6 and Global Initiative for Asthma [GINA] step 5) sensitized to at least 1 allergen who had received AIT within the previous 5 years, to evaluate safety and effectiveness. Results: The study included 93 patients (54.8% female) with a median age of 40.3 years, including 5 under 14. A total of 16 systemic reactions (SRs) were reported in 8 patients (8.6%), mostly immediate (13/16) and occurring during the initiation phase (12/16), all in patients receiving subcutaneous immunotherapy. Most SRs were mild to moderate, except for 2 severe reactions in 1 patient. Only 3 patients discontinued treatment. Significant improvements in both FeNO and FEV Conclusion: This study confirms the safety and effectiveness of AIT in patients with well-controlled severe asthma in routine clinical practice. Additional prospective real-world studies are needed to better understand the efficacy of AIT in severe asthma.