Analysis of safety, risk factors and pretreatment methods during rush hymenoptera venom immunotherapy

The safety profile of venom immunotherapy is a relevant issue. We evaluated the frequency of severe adverse events (SAE), associated risk factors, retrospective comparison of pretreatment protocols including solely H1 receptor blockers and a combination of H1 and H2 receptor blockers during rush Hymenoptera venom immunotherapy.

The study group comprised 118 patients. The treatment was initiated according to a 5-day rush protocol with the use of standardized venom allergens of either wasp or honeybee.

During the rush induction, side effects occurred in 18 patients (15.2%), whereas SAE were present in 7 patients (5.9%). Twelve out of 18 (66.6%) developed anaphylactic reactions on the fourth day of the rush protocol, with the majority of cases at a dose of 40 or 60 microg of the venom extract (p = 0.001). The frequency of SAE was also significantly higher on the fourth day than thereafter (p = 0.0001) as well as in patients allergic to bee venom (p = 0.049). All systemic side effects were more frequent in women (p = 0.0065). However, this relation was not true when SAE were consider (p = 0.11). A higher percentage of SAE was observed in the subjects pretreated with both H1 and H2 receptor antagonists than in those pretreated with H1 blocker only (8.8 vs. 4.1%); however, the difference was not significant.

Considerable severity of allergic adverse events requires particular attention to patients allergic to bee venom and during rush phase, especially when rapidly increasing doses are administered. Pretreatment with H2 blockers is debatable and warrants further investigation.