Evaluation of the risk of anaphylactic reactions by wasp venom-extract challenges in children

Diagnostic sting challenges have been shown to provide information on the r isk of further anaphylactic reactions to bee stings. We present a. follow-u p study in wasp venom-hypersensitive children after diagnostic venom extrac t challenges to analyze their risk of further anaphylactic reactions. Respo nses were obtained from 104 patients with wasp venom hypersensitivity out o f 115 former patients. Only one of the 104 patients showed more than a seve re local reaction to the sting challenge irrespective of the performance of a single or sequential challenge; therefore, only one patient received ven om immunotherapy. The performance of a diagnostic sting challenge with wasp venom extract in children had a high negative predictive value of 94.6% fo r the risk of further systemic reactions. This was shown by analysis of lat er field stings, since 37 children experienced further field stings and onl y two of these children (5.4%) developed a mild systemic reaction (urticari a) equal to or less severe than the index sting. The value of the venom ext ract challenge can be interpreted in two ways: either it is less sensitive than a native sting challenge since the rate of systemic reactions to the c hallenge was very low, or the prognosis of wasp venom hypersensitivity in c hildren is extremely favorable. Since the latter hypothesis is supported by the low incidence of systemic field sting reactions, we postulate that ven om immunotherapy is necessary only in a minority of children with wasp veno m hypersensitivity with an index sting reaction of Mueller grade I or II. H owever, the value of venom extract challenges as a general diagnostic instr ument in children with Mueller I and II reactions due to wasp venom hyperse nsitivity may be questioned. It may have a place as a safe procedure in dem onstrating to parents and physicians the often self-limiting natural course in most of these children.