Efficacy of venom immunotherapy given every 3 or 4 months: a prospective comparison with the conventional regimen.

Background: Standard venom immunotherapy involves the administration of the maintenance dose every 4 to 6 weeks. This regimen may have adherence problems, especially in the long term; thus, extended intervals have been proposed.

Objective: We prospectively compared the efficacy of 3- or 4-month extended maintenance dose vs the conventional regimen.

Methods: Patients receiving immunotherapy with a single venom were offered the extended maintenance dose (EMD) 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 comparable group of patients receiving the conventional maintenance dose (CMD) was used for comparison by logistic regression analysis.

Results: Seventy-six patients (60 male; mean age, 48 years) receiving the EMD were re-stung on 247 occasions by the insect for which they were receiving immunotherapy. The group receiving CMD included 110 patients (82 male; mean age, 44 years) certainly re-stung on 167 occasions by the specific insect. The percentage of re-sting without reaction was 93.5% in the EMD group and 81.5% in the CMD group, with a significant difference in favor of the former (P=.001). At logistic regression analysis, only age, but not maintenance dose protocol, was predictive of subsequent systemic reactions.

Conclusion: The EMD is as effective and safe as the CMD. An increased maintenance seems to be the best option in term of convenience and economic savings.