Evaluation of a modified skin prick test for diagnosis of Hymenoptera venom allergy

Abstract

Skin tests are an integral part in the diagnosis of allergy to Hymenoptera venom (HV). While usually these include skin prick tests (SPT) and intradermal tests (IDT) with venom extracts at a maximum concentration of 100 μg/ml and 1 μg/ml, respectively, in addition, a SPT with 300 μg/ml (SPT300) may be performed. The purpose of this study was to evaluate the diagnostic value of SPT300. In all, 75 patients with history of anaphylaxis to HV were evaluated by SPT and IDT, including SPT300, as well as measuring HV-specific IgE antibodies. In a subgroup of monosensitized patients with IgE antibodies to either only wasp (WV) or bee venom (BV) the specificity and sensitivity of SPT300 was assessed. While 64 % and 68 % patients showed positive test results in SPT with 100 μg/ml (SPT100) and IDT with 1 μg/ml (IDT1) HV, respectively, 82.7 % reacted to SPT300, considering a mean wheal diameter (MWD) of at least 3 mm a positive skin reaction. Choosing either a MWD of 4 or 5 mm as threshold, merely 69.3 % and 32 % had a positive test result. Evaluation of individuals monosensitized to only WV (n = 27) or BV (n = 10) by IgE analysis revealed an almost equally satisfactory sensitivity of more than 80 % for SPT300, but also for SPT100 and IDT1 with both allergens. Of note, while the specificity of SPT300 for WV exceeded 90 %, it was markedly lower for SPT300 with BV (51.9 %). Other factors like atopy, grade of anaphylaxis, and the time lag between index sting and skin testing had no influence on the test results. SPT300 shows a high but not substantially superior sensitivity utilizing both WV and BV extract for diagnosis of HV allergy compared to SPT100 and IDT1. However, since SPT300 with BV extract demonstrated a very low specificity, our results indicate that SPT300 has limited added value in the diagnosis of HV allergy.