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J Allergy Clin Immunol Pract. 2017 May - Jun;5(3):676-683. doi: 10.1016/j.jaip.2017.03.014.

Positive Skin Test or Specific IgE to Penicillin Does Not Reliably Predict Penicillin Allergy.

Author information

1
Odense Research Center for Anaphylaxis, Odense, Denmark; Department of Dermatology and Allergy Center, Odense University Hospital, Odense, Denmark. Electronic address: line.tannert@rsyd.dk.
2
Odense Research Center for Anaphylaxis, Odense, Denmark; Department of Dermatology and Allergy Center, Odense University Hospital, Odense, Denmark.
3
Odense Research Center for Anaphylaxis, Odense, Denmark; Department of Dermatology and Allergy Center, Odense University Hospital, Odense, Denmark; RefLab Aps., Copenhagen, Denmark.

Abstract

INTRODUCTION:

According to guidelines, patients are diagnosed with penicillin allergy if skin test (ST) result or specific IgE (s-IgE) to penicillin is positive. However, the true sensitivity and specificity of these tests are presently not known.

OBJECTIVE:

To investigate the clinical relevance of a positive ST result and positive s-IgE and to study the reproducibility of ST and s-IgE.

METHODS:

A sample of convenience of 25 patients with positive penicillin ST results, antipenicillin s-IgE results, or both was challenged with their culprit penicillin. Further 19 patients were not challenged, but deemed allergic on the basis of a recent anaphylactic reaction or delayed reactions to skin testing. Another sample of convenience of 18 patients, 17 overlapping with the 25 challenged, with initial skin testing and s-IgE (median, 25; range, 3-121), months earlier (T-1), was repeat skin tested and had s-IgE measured (T0), and then skin tested and had s-IgE measured 4 weeks later (T1).

RESULTS:

Only 9 (36%) of 25 were challenge positive. There was an increased probability of being penicillin allergic if both ST result and s-IgE were positive at T0. Positive ST result or positive s-IgE alone did not predict penicillin allergy. Among the 18 patients repeatedly tested, 46.2% (12 of 25) of positive ST results at T-1 were reproducibly positive at T0. For s-IgE, 54.2% (14 of 24) positive measurements were still positive at T0 and 7 converted to positive at T1.

CONCLUSIONS:

The best predictor for a clinically significant (IgE-mediated) penicillin allergy is a combination of a positive case history with simultaneous positive ST result and s-IgE or a positive challenge result.

KEYWORDS:

Penicillin allergy; Penicillin challenge; Skin test reproducibility; Specific IgE to penicillin reproducibility

Comment in

PMID:
28483318
DOI:
10.1016/j.jaip.2017.03.014
[Indexed for MEDLINE]

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