The VISYT trial: Venom Immunotherapy Safety and Tolerability with purified vs nonpurified extracts

Background: Venom immunotherapy (VIT) is a highly effective treatment but can induce systemic adverse effects. Objective: To evaluate the safety and tolerability of VIT with purified and nonpurified extracts for treating yellow jacket and honeybee allergy. Methods: Ninety-four patients (mean age, 46 years) with a history of insect venom allergy were randomly allocated to undergo purified extract VIT (group A [44 patients]) or nonpurified extract VIT (group B [50 patients]). Fifty-six patients were allergic to yellow jacket venom (group A: 25; group B: 3 1) and 38 to honeybee (19 per group). The induction phase was performed using a 2- or 7-day ultrarush scheme. The maintenance phase lasted 11 weeks. Local and systemic reactions were recorded after each injection. Results: A total of 1,401 VIT injections were performed. Six systemic reactions were observed in 4 patients (honeybee-allergic patients only) (4% of patients; 0.4% of injections): 1 patient in group A (2%) and in 3 in group B (6%) (P = .57). Local extensive reactions were recorded after 5 injections in 4 patients (9%) in group A (2 yellow jacket- and 2 honeybee-allergic patients) and after 17 injections in 12 patients (24%) in group B (8 yellow jacket- and 4 honeybee-allergic patients) (P = .02). Total reactions (systemic and large local) numbered 6 in group A (0.9% of injections; 11% of patients) and 20 in group B (2.7% of injections; 30% of patients) (P = .001). Conclusion: In patients with honeybee or yellow jacket venom allergy, VIT with purified extracts has a significantly lower propensity toward severe local reactions compared with VIT with nonpurified extracts. Ann Allergy Asthma Immunol. 2009; 103:57-61.