Safety of a two-day ultrarush insect venom immunotherapy protocol in comparison with protocols of longer duration and involving a larger number of injections

Background: Insect venom inmunotherapy (VIT) is initiated by a dose increase protocol administered usually over 7 to 9 days. Shorter protocols have the advantage of reducing the patient's stay in the hospital. Very few data are currently available on the safety of shorter VIT dose increase protocols. Objective: The aim of this study was to investigate whether a reduction in the duration of the VIT dose increase protocol from 7 to 9 days to 2 days causes an increase in the incidence and severity of adverse reactions. Methods: Between 1992 and 1997 we administered VIT to 1055 patients allergic to bee or wasp venom. We shortened the 7- to 9-day rush protocol stepwise to 2 days by reducing the number of injections and increasing the initial dose and compared the incidence and severity of adverse reactions. The patients were retrospectively divided into 3 cohorts: 20 injections over 7 to 9 days (cohort 1, 317 patients), 10 to 14 injections over 3 to 6 days (cohort 2, 335 patients), and 9 injections over 2 days (cohort 3, 403 patients). Results: We observed no severe adverse reactions in any of the cohorts during VIT. Adverse reactions were treated in 7.1% of the patients by oral and in 2.9% by intravenous antihistamines and in 0.8% by systemic corticosteroids. The incidence of adverse reactions declined significantly from 22.4% in cohort 1 to 13.7% in cohort 2 and 10.7% in cohort 3 with reduced number of injections (P < .001). Conclusion: The incidence and severity of adverse reactions decline if the VIT dose increase protocol is shortened to 2 days.