Yonsei Med J.  2018 Oct;59(8):968-974. 10.3349/ymj.2018.59.8.968.

Proper Cut-off Levels of Serum Specific IgE to Cefaclor for Patients with Cefaclor Allergy

  • 1Department of Internal Medicine, College of Medicine, Dong-A University, Busan, Korea.
  • 2Department of Allergy and Clinical Immunology, Ajou University School of Medicine, Suwon, Korea. ye9007@ajou.ac.kr
  • 3Pharmacovigilance Center, Ajou University Hospital, Suwon, Korea.


Cefaclor, a second-generation oral cephalosporin, is known to cause IgE-mediated hypersensitivity. Assays of serum-specific IgE (sIgE) to cefaclor are commercially available via the ImmunoCAP system (Thermo Fisher Scientific). While serum levels of sIgE >0.35 kU/L are considered indicative of an allergy, some patients with cefaclor allergy show low serum IgE levels. This study aimed to evaluate the proper cut-off levels of sIgE in the diagnosis of immediate hypersensitivity to cefaclor.
A total of 269 patients with drug allergy history, who underwent assays of sIgE to cefaclor at Ajou University hospital and Dong-A University Hospital, were reviewed retrospectively. Among them, 193 patients exhibited cefaclor-induced immediate hypersensitivity with certain or probable causality of an adverse drug reaction according to the WHO-UMC (the World Health Organization-the Uppsala Monitoring Centre) algorithm, and 76 controls showed delayed hypersensitivity reactions to non-antibiotics.
In total, 126 of the 193 patients (65.3%) experienced anaphylaxis; they had higher serum sIgE levels than patients with immediate hypersensitivity who did not experience anaphylaxis (6.36±12.39 kU/L vs. 4.28±13.61 kU/L, p < 0.001). The best cut-off value for cefaclor-induced immediate hypersensitivity was 0.11 kU/L, with sensitivity of 80.2% and specificity of 81.6%. A cut-off value of 0.44 kU/L showed the best sensitivity (75.4%) and specificity (65.7%) for differentiating anaphylaxis from immediate hypersensitivity reactions.
Patients with cefaclor anaphylaxis exhibit high serum IgE levels. A cut-off value of 0.11 kU/L of sIgE to cefaclor is proper for identifying patients with cefaclor allergy, and 0.44 kU/L may be useful to detect anaphylaxis.


Anaphylaxis; cefaclor; drug hypersensitivity; specific IgE

MeSH Terms

Drug Hypersensitivity
Drug-Related Side Effects and Adverse Reactions
Global Health
Hypersensitivity, Delayed
Hypersensitivity, Immediate
Immunoglobulin E*
Retrospective Studies
Sensitivity and Specificity
Immunoglobulin E


  • Fig. 1 Selection of study subjects.

  • Fig. 2 Levels of serum sIgE to cefaclor according to clinical phenotypes of cefaclor hypersensitivity. sIgE, specific IgE.

  • Fig. 3 ROC curves for determining immediate hypersensitivity to cefaclor (A) and discriminating anaphylaxis among patiens with cefaclor hypersensitivity (B). sIgE, specific IgE; CI, confidence interval; AUC, area under the curve; ROC, receiver operating characteristic.


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