Single-step direct drug provocation testing is safe for delabelling selected non–low-risk penicillin allergy labels

Abstract

BackgroundPenicillin allergy labels are prevalent, and removal of incorrect labels improves patient outcomes and health economics. Labels may be classified as “low-risk” or “non–low-risk,” of which the symptoms of the latter chiefly suggest immunoglobulin E–mediated etiology. Traditionally, “non–low-risk” allergy labels are evaluated by penicillin skin testing followed by graded multistep penicillin drug provocation testing (DPT). ObjectiveTo evaluate the safety of assessing “non–low-risk” labels with single-step direct DPT. MethodsWe consecutively enrolled inpatients and outpatients of a teaching hospital in Sydney, Australia, with penicillin allergy labels requiring penicillin for first-line treatment. Patients were classified as “low-risk” or “non–low-risk” based on the allergy labels. All patients proceeded directly to amoxicillin DPT, unless there was a history of anaphylaxis within 10 years of assessment to a beta-lactam (except for cefazolin) or Gell and Coombs type 2, type 3, or severe type 4 reaction. This was followed by a course of amoxicillin. ResultsA total of 149 patients (41 inpatients, 108 outpatients) were enrolled. No patient was excluded from the study. No patient experienced life-threatening reactions to the protocol. There were 85 patients who reported “non–low-risk” allergy labels. One patient developed generalized pruritus and rash that resolved with standard-dose antihistamines, 2 developed delayed benign maculopapular exanthem, and 3 experienced diarrhea during the course of amoxicillin. ConclusionIn our cohort, direct single-step DPT was safe, with only 6 patients with “non–low-risk” allergy experiencing benign reactions. We hope that further studies can be performed into single-step direct DPT to evaluate “non–low-risk” penicillin allergy labels. Trial RegistrationClinicalTrials.gov Identifier: LNR/16/HAWKE/452.