Background The sting challenge test (SCT) is regarded as the most reliable method for assessing the effectiveness of venom immunotherapy (VIT). However, its predictive value in patients undergoing VIT is still unclear. This study aims to evaluate the predictive value of the SCT. Methods A multicenter retrospective observational study was conducted on patients receiving VIT who underwent SCT. The study gathered data on patient demographics, diagnosis, immunotherapy details, outcomes of the SCT and their comparison to subsequent field sting (FS) results. Results A total of 261 patients were included, and 372 SCT were recorded. The majority of the patients (75.1%) were men. A diagnosis of mastocytosis was confirmed in 7.7%. The final diagnoses were allergy to Apis mellifera (48.7%), Polistes dominula (36.8%), Vespula spp. (2.7%) and Polistes dominula plus Vespula spp. (10,7%). Sting challenge tests were performed with Apis in 61.6% of the overall tests, Polistes in 34.1% and Vespula in 4.3%. The majority (95.7%) of the SCT were negative. Regarding FS, 146 patients (56.2%) experienced 306 FS of which 95.1% were negative. Among these 146 patients, 137 had a negative SCT, and 130 of these also had a subsequent negative FS, resulting in a 94.9% of negative predictive value (NPV) of the test. Of the patients who experienced FS, 9 had a positive SCT and only 3 of them had a positive FS, resulting in a positive predictive value of 33,3%. Conclusions SCT is a safe procedure, and its high NPV emphasizes the usefulness of this test in assessing the effectiveness of VIT.

Insect venom allergy is the most frequent cause of anaphylaxis in Europe and possibly worldwide. The majority of systemic allergic reactions after insect stings are caused by Hymenoptera and among these, vespid genera induce most of the systemic sting reactions (SSR). Honey bees are the second leading cause of SSR. Depending on the global region, other Hymenoptera such as different ant genera are responsible for SSR. Widely distributed hornets and bumblebees or local vespid or bee genera rarely induce SSR. Hematophagous insects such as mosquitoes and horse flies usually cause (large) local reactions while SSR occasionally occur. This position paper aims to identify either rare or locally important insects causing SSR as well as rarely occurring SSR after stings or bites of widely distributed insects. We summarized relevant venom or saliva allergens and intended to identify possible cross-reactivities between the insect allergens. Moreover, we aimed to locate diagnostic tests for research and routine diagnosis, which are sometimes only regionally available. Finally, we gathered information on disposable immunotherapies. Major allergens of most insects were identified, and cross-reactivity between insects was frequently observed. While some diagnostics and immunotherapies are locally available, standardized skin tests and immunotherapies are generally lacking in rare insect allergy.