Predictors of Severe Anaphylaxis In Hymenoptera Venom Allergy: The Importance of Absence of Urticaria/Angioedema.

Background: Severe anaphylaxis (SA) in Hymenoptera venom allergy has been associated with a number of risk factors. However, the effect of several of those risk factors on the severity of anaphylaxis is poorly defined. Objective: To evaluate risk factors for SA in Hymenoptera venom allergy. Methods: We evaluated data from 500 patients who were referred to our department for the diagnosis of Hymenoptera venom allergy during a period of 11 years to identify risk factors for SA. Results: Six significant risk factors for SA were identified (P <.05): short interval from sting to reaction, absence of urticaria or angioedema (U/A) during anaphylaxis, older age, male sex, elevation of baseline serum tryptase (BST) level, and diagnosis of systemic mastocytosis. Moreover, elevation in BST level was significantly associated with the absence of U/A and older age. No association could be established between SA and comorbidities, concurrent cardiovascular medication, or the severity of the systemic reaction during the initiation of venom immunotherapy. Conclusion: Apart from BST and older age, male sex, short interval from sting to reaction, and absence of U/A are also risk factors for SA. The association between elevated BST level and SA was largely confined to those who had an absence of U/A after field sting, possibly because of the higher risk of concurrent systemic mastocytosis. Patients with an SA after a field sting do not have an elevated risk of systemic reactions during the initiation of venom immunotherapy compared with patients with mild anaphylaxis; therefore, additional preventive measures are not necessary. (C) 2020 American College of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.