Age-dependent sting recurrence and outcome in immunotherapy-treated children with anaphylaxis to Hymenoptera venom.

BACKGROUND Data on outcome of insect venom immunotherapy in children are rare. OBJECTIVE We investigated the rate of sting recurrence and outcome of Hymenoptera venom anaphylaxis in children of different age groups treated with immunotherapy. METHODS Data from children consecutively referred for anaphylaxis to Hymenoptera venom were collected using a standardized questionnaire. RESULTS During mean follow-up of 7.7 years after commencement of immunotherapy, 45 of 83 children (56%) were re-stung 108 times by the insect they were allergic to. This corresponds to a rate of 0.23 stings per child and year of follow-up. The younger the subject, the higher was the prevalence of re-stings, with rates of 0.41 in children < 6 years, 0.21 at school age and 0.15 in adolescents (P = 0.001). In contrast, prevalence of systemic allergic reactions to field stings was significantly lower in pre-school (3.4%) and school-age children (4.3%) compared with adolescents (15.6%; P < 0.05). Overall, prevalence of systemic allergic reactions at re-sting was 15.6% in the honey bee venom and 5.9% in the Vespula venom allergic group (P = ns). Younger boys with anaphylaxis to honey bee venom predominated in our cohort (P = 0.019). CONCLUSION AND CLINICAL RELEVANCE A majority of children with anaphylaxis to Hymenoptera venom (56%) in our cohort were re-stung, equally by honey bees or Vespula species. Younger children were more likely to be re-stung, but less likely to have a systemic reaction. Venom immunotherapy induces long-term protection in most children: 84.4% of subjects with anaphylaxis to honey bee and 94.1% of those to Vespula venom were completely protected at re-stings.