91 Efficacy of Venom Immunotherapy Given Every 3 or 4 Months. A Direct Prospective Comparison With the Conventional Regimen

BACKGROUND: The standard venom immunotherapy involves the administration of the maintenance dose every 4 to 6 weeks. This regimen may have compliance problem especially in the long term, thus extended intervals have been proposed. We prospectively compared the efficacy of 3- or 4-month extended maintenance dose and the conventional regimen. METHODS: Patients receiving immunotherapy of a single venom were offered the delayed maintenance dose, and were then followed-up for field re-stings. Only the re-stings by the insect for which the patients received immunotherapy were considered. A matched group of patients receiving the conventional maintenance were used for comparison, by univariate and multivariate analysis. RESULTS: Fifty-two patients (44 male, 8 female, mean age 52 years) were certainly re-stung on 113 occasions by the insect for which they were receiving immunotherapy. 90 re-stings occurred during the 3- month maintenance and 23 during the 4-month maintenance. The control group, on conventional protocol with one single venom, included 103 patients (79 male, 24 female, mean age 41 years) certainly re-stung on 160 occasions by the specific insect. The rate of re-sting without reaction was 97% in the delayed maintenance and 82% in the conventional group with a significant difference in favour of the former (P = 0.01). None of the variables considered resulted predictive for systemic reactions by logistic regression analysis CONCLUSIONS: The delayed maintenance dose approach is al least as effective and safe as the conventional one. The 4-month maintenance seems to be the best option in term of convenience and economic save.