The value of an in-hospital insect sting challenge as a criterion for application or omission of venom immunotherapy

Background: Venom immunotherapy is a generally accepted treatment for serious allergy to bee and yellow jacket venom. However, It is not precisely known to whom venom immunotherapy should be offered. Objective: The purpose of this study was to determine whether an in-hospital insect sting challenge (IHC) can be used as a criterion for application or omission of venom immunotherapy. Methods: An IHC was carried out in a group of 479 patients (136 sensitized to bee venom and 343 sensitized to yellow jacket venom). The patients with a negative IHC response were interviewed about their experience with subsequent stings under natural circumstances. Results: A total of 76 of 136 bee-sensitized patients (56%) and 284 of 343 yellow jacket-sensitized patients (83%) had a negative IHC response. All of the patients who had a systemic reaction after the IHC were advised to receive venom immunotherapy. The success rate of this therapy was 96.4% for patients allergic to bee venom (54 of 56) and 91.4% for patients allergic to yellow jacket venom (53 of 58). Of a total of 76 bee-sensitized patients with negative IHC responses, 41 were subsequently stung in the field; six patients had a mild (Mueller grade I) systemic reaction (14.6%). Of a total of 284 yellow jacket-sensitized with negative IHC responses, 127 were subsequently stung in the field; nine patients had a mild (Mueller grade I) systemic reaction (14.6%). Of a total of 284 yellow jacket-sensitized with negative IHC responses, 127 were subsequently string in the field; nine patients had a mild (Mueller grades I and II) systemic reaction (7.1%), and four patients had a severe (Mueller grades III and IV) systemic reaction (3.1%). Without IHC as a selection criterion for venom immunotherapy, the percentage of patients unnecessarily treated was calculated to be 48% for bee venom-sensitized patients and 74% for yellow jacket-sensitized patients. However, with a negative test IHC response as a selection criterion for the omission of venom immunotherapy, 14.6% of the bee venom-sensitized patients and 10.2% of the yellow jacket-sensitized patients were proven to be at risk for systemic reactions on subsequent field stings. Conclusion: Venom immunotherapy with bee or yellow jacket venom is justifiable only after a positive response to an IHC is observed.