title: Improving the Effectiveness of Penicillin Allergy De-labeling.
abstract: BACKGROUND
  Approximately 10-20% of hospitalized patients are labeled as penicillin allergic, and this is associated with significant health and economic costs.
  
  
  OBJECTIVE
  We looked at the effectiveness of penicillin allergy de-labeling in clinical practice with the aim of deriving risk stratification models to guide testing strategies.
  
  
  METHODS
  Consecutive patients aged 15 years or more, referred to a Western Australian public hospital drug allergy service between 2008 and 2013 for beta-lactam allergy, were included. Follow-up surveys were conducted. Results of skin prick testing and intradermal testing (SPT/IDT) and oral challenge (OC), and follow-up of post testing antibiotic usage were the main outcomes.
  
  
  RESULTS
  SPT/IDT was performed in 401 consecutive patients with immediate (IMM) (≤ 1 hour) (n = 151) and nonimmediate (NIM) (>1 hour) (n = 250) reactions. Of 341 patients, 42 (12.3%) were SPT/IDT+ to ≥ 1 penicillin reagents, including 35/114 (30.4%) in the IMM group and 7/227 (3.1%) in the NIM group (P < .0001). Of 355 SPT/IDT patients, 3 (0.8%), all in the IMM group, had nonserious positive OC reactions to single dose penicillin VK (SPT/IDT negative predictive value [NPV] 99.2%). Selective or unrestricted beta-lactam was recommended in almost 90% overall, including 238/250 (95.2%) in the NIM group and 126/151 (83.4%) in the IMM group (P = .0001). Of 182 patients, 137 (75.3%) were following the allergy label modifications (ALM) at the time of follow-up.
  
  
  CONCLUSIONS
  Penicillin SPT/IDT/OC safely de-labels penicillin-allergic patients and identifies selective beta-lactam allergies; however, incomplete adherence to ALM recommendations impairs effectiveness. Infrequent SPT/IDT+ and absent OC reactions in patients with NIM reactions suggest OC alone to be a safe and cost-effective de-labeling strategy that could improve the coverage of penicillin allergy de-labeling in lower risk populations.
authors.affiliation: Department of Clinical Immunology, Sir Charles Gairdner Hospital, Perth, Western Australia, Australia; Department of Clinical Immunology, Royal Perth Hospital, Perth, Western Australia, Australia.
authors.forename: Jack
authors.initials: J
authors.lastname: Bourke
authors.affiliation: Institute for Immunology & Infectious Diseases, Murdoch University, Perth, Western Australia, Australia.
authors.forename: Rebecca
authors.initials: R
authors.lastname: Pavlos
authors.affiliation: Institute for Immunology & Infectious Diseases, Murdoch University, Perth, Western Australia, Australia.
authors.forename: Ian
authors.initials: I
authors.lastname: James
authors.affiliation: Department of Clinical Immunology, Sir Charles Gairdner Hospital, Perth, Western Australia, Australia; Department of Clinical Immunology, Royal Perth Hospital, Perth, Western Australia, Australia; Institute for Immunology & Infectious Diseases, Murdoch University, Perth, Western Australia, Australia; Vanderbilt University School of Medicine, Nashville, Tenn. Electronic address: elizabeth.j.phillips@vanderbilt.edu.
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Phillips
mesh_terms: D000284:Administration, Oral; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000900:Anti-Bacterial Agents / Q000008:administration & dosage / Q000009:adverse effects*; D004342:Drug Hypersensitivity / Q000175:diagnosis* / Q000276:immunology; D005260:Female; D019983:Guideline Adherence; D006779:Hospitals, Public; D006801:Humans; D007428:Intradermal Tests / Q000592:standards; D008297:Male; D008875:Middle Aged; D018579:Patient Selection; D010406:Penicillins / Q000008:administration & dosage / Q000009:adverse effects*; D017410:Practice Guidelines as Topic; D011237:Predictive Value of Tests; D018570:Risk Assessment; D012307:Risk Factors; D013997:Time Factors; D014904:Western Australia; D055815:Young Adult
chemical_list: D000900:Anti-Bacterial Agents; D010406:Penicillins
keywords: Allergy; De-labeling; Oral challenge; Penicillin; Skin testing; Stewardship