Clinical Relevance of Specific IgE in Penicillin Allergy Investigation

Victor Lendal; Sara Fransson; Holger Mosbech; Jonas Bredtoft Boel; Natasha Kahlhofen; Lars H Blom; Lars K Poulsen; Lene H Garvey

doi:10.1159/000541243

Clinical Relevance of Specific IgE in Penicillin Allergy Investigation

Int Arch Allergy Immunol. 2024 Oct 25:1-8. doi: 10.1159/000541243. Online ahead of print.

Authors

Victor Lendal¹, Sara Fransson¹, Holger Mosbech¹, Jonas Bredtoft Boel², Natasha Kahlhofen¹, Lars H Blom¹, Lars K Poulsen¹, Lene H Garvey^{1

3}

Affiliations

¹ Allergy Clinic, Department of Dermatology and Allergy, Copenhagen University Hospital-Herlev and Gentofte, Copenhagen, Denmark.
² Department of Clinical Microbiology, Copenhagen University Hospital-Herlev and Gentofte, Copenhagen, Denmark.
³ Department of Clinical Medicine, University of Copenhagen, Copenhagen, Denmark.

PMID: 39462501
DOI: 10.1159/000541243

Abstract

Introduction: Patients with immediate type allergic reactions to penicillins are at risk of anaphylaxis on reexposure. Diagnostic gold standard is drug provocation test (DPT) if allergy is not diagnosed by other means, such as skin testing or in vitro testing with measurement of specific IgE. Specific IgE testing carries low risk for the patient and blood sampling can be performed in primary care, but it is reported to have low sensitivity. The aim of this study was to evaluate if clinical characteristics of patients with suspected allergic reactions to penicillin and elevated specific IgE to penicillins, differed from patients without specific IgE, to identify predictors for elevated specific IgE to penicillins.

Methods: Levels of specific IgE to five penicillins (penicillin G, penicillin V, amoxicillin, ampicillin, and penicillin minor determinants) were available for 9,100 patients. Using multiple logistic regression, clinical data from 430 patients in this group who had elevated specific IgE to one or more penicillins were compared to data from 4,094 patients without specific IgE to penicillins, who had undergone DPT with a penicillin.

Results: In total 5.2% of patients had elevated specific IgE to one or more penicillins. Significantly more patients with elevated specific IgE had a history of immediate type reactions (<2 h) (OR = 4.34, p < 0.001); circulatory symptoms (OR = 1.63, p = 0.03) or angioedema (OR = 1.46, p = 0.005). Also, significantly more patients with elevated specific IgE had been treated with adrenaline (OR = 2.21, p = 0.005), steroids (OR = 1.76, p < 0.001), or antihistamines (OR = 1.83, p < 0.001).

Conclusion: A history of an immediate type reaction requiring treatment, combined with elevated specific IgE to one or more penicillins is suggestive of an IgE mediated penicillin allergy and further allergy investigations may not be needed. Specific IgE to penicillins may be used early in allergy investigation of patients with severe immediate type reactions to penicillins.

Keywords: Drug allergy; Immediate type drug hypersensitivity; In vitro diagnostics; Penicillin allergy; Specific IgE.