Flexible approaches in the design of subcutaneous immunotherapy protocols for Hymenoptera venom allergy

Background: Venom immunotherapy is an effective method for the treatment of Hymenoptera venom allergy. Different extracts and treatment schedules are available. Objective: To compare the safety and efficacy of immunotherapy in 3 cohorts of patients sensitized to Vespula species. Methods: In this open study, 43 patients were treated with a subcutaneous aqueous extract for induction and maintenance (AA), 34 with a subcutaneous depot extract for induction and maintenance (DD), and 29 with subcutaneous aqueous and subcutaneous depot extracts for induction and maintenance, respectively (AD). Cluster schedules were followed to reach maintenance, and adverse effects during treatment and after naturally occurring stings were recorded. Results: Depot immunotherapy was better tolerated mainly owing to the lower frequency of local adverse effects in the induction phase (5.9% vs 42.5% and 1.3% vs 5.1% on a per patient and per dose basis, respectively; P < .001 for both) and for effects occurring within 60 minutes after vaccination (2.9% vs 19.2% and 0.2% vs 2.8% on a per patient and per dose basis; P = .03 and P < .001, respectively). Furthermore, 19 of 20 AA, 9 of 9 AD, and 10 of 10 DD patients who were restung experienced only minor local effects. Conclusions: Venom immunotherapy is efficacious. Although there was no decrease in systemic reactions, depot immunotherapy to Vespula venom induced fewer early local adverse effects. Patients undergoing an induction phase with an aqueous extract can benefit from switching to a depot extract during maintenance. Increasing the flexibility of the immunization schedules may improve compliance with this potentially lifesaving treatment.