Efficacy and safety of hymenoptera venom immunotherapy

Background: Being stung by Hymenoptera species can cause life-threatening anaphylaxis. Although venom immunotherapy (VIT) seems to be the most effective treatment, its long-term efficacy, and risk factors for adverse events remain unclear. Objective: The objective was to investigate the long-term efficacy of VIT and evaluate adverse events and risk factors related to this. Method: Patients who received VIT in a tertiary-care adult allergy clinic between January 2005 and July 2022 were included. Patients' data were compared with those of individuals who had been diagnosed with bee and/or wasp venom allergy during the same period but had not received VIT and experienced field re-stings. Results: The study included 105 patients with venom allergy, of whom 68 received VIT and 37 did not receive VIT. Twenty-three patients (34%) completed 5 years of VIT, and the overall mean ± standard deviation VIT duration was 46.9 ± 20.9 months. Re-stings occurred in 5 of 23 patients who completed 5 years of VIT, and none of them developed a systemic reaction. Eighteen patients (40%) experienced re-stings after prematurely discontinuing VIT, of whom eight (44%) developed a systemic reaction. In the control group of patients who did not receive VIT, 26 patients (70.3%) experienced re-stings, and all had systemic reactions (100%), with no change in their median Mueller scores. There was a significant difference in the median Mueller score change between the patients who received VIT and the controls who did not (p = 0.016). A total of 13 patients (19%) experienced adverse events while receiving VIT, which were systemic reactions in nine honeybee VIT. The use of β-blockers was determined as the most important risk factor (odds ratio 15.9 [95% confidence interval, 1.2-208.8]; p = 0.035). Conclusion: It was confirmed that VIT was effective in both reducing the incidence and the severity of re-sting reactions. These effects were more pronounced in the patients who completed 5 years of VIT.