Winged hymenoptera: Discordance between In vitro and In vivo sensitization

<b>Background:</b> An Hymenoptera venom allergy diagnosis requires sting-triggered systemic reaction symptoms and evidence of venom-specific immunoglobulin E (IgE) through skin or serologic testing. A lack of concordance between skin and serologic testing has been reported previously; using these tests in a complementary fashion has been emphasized in published guidelines. <b>Objective:</b> We assessed skin and serologic venom-specific IgE testing discordance and factors that impact the testing. <b>Methods:</b> A retrospective review of patients with allergist-diagnosed winged Hymenoptera venom allergy prescribed venom immunotherapy at one center from 2005 to 2023 was completed. Record review included demographics, Mueller grading reaction severity, and venom testing results. Patients were included if they had both skin and serologic testing results. <b>Results:</b> A total of 125 records were reviewed, with 33 meeting inclusion criteria. Patients were 7-69 years old, 55% female, and Mueller grade 2 and above reactions occurred in 94%. Kappa coefficients for both tests for individual winged Hymenoptera were all <0.35. Discordance occurred 37% of the time overall; no venom was found to be more or less discordant than the others. Skin testing results were found to be positive more frequently than were serologic testing results overall (p = 0.0126), in male individuals (p = 0.007), when the initial sting was at >18 years old (p = 0.016), when testing was completed at >30 years old (p = 0.006), and when there were >5 years between the initial sting and testing (p = 0.007). <b>Conclusion:</b> Skin and serologic testing for winged Hymenoptera are frequently discordant, and both should be tested to confirm or refute negative results. In certain populations, skin testing should be completed first.