The Use of Penicillin Allergy Clinical Decision Rule to Enable Direct Oral Penicillin Challenge

Patient-reported penicillin allergies result in poor health outcomes for patients and drive inappropriate antibiotic prescribing, antimicrobial resistance and healthcare costs. Our group has internally and externally validated a novel penicillin allergy clinician decision rule (PEN-FAST) that is able to identify low risk penicillin allergies with a negative predictive value of 96% (95%; 94-98%). Therefore, whilst validated tools exist to enable inpatient penicillin assessment and de-labelling, limited evidence is available regarding the safety and efficacy in the outpatient clinic. The ability to deliver point-of-care penicillin allergy testing for a large cohort of patients, without skin testing, will improve patient access to testing and utilization of preferred penicillin antibiotics.

Inclusion criteria

• Adult patients referred to the outpatient allergy clinic for a penicillin allergy history;
• Willing and able to give consent.

Exclusion criteria

• Patient age is < 18 years;
• Patients with a PEN-FAST score less than 3
• Pregnancy;
• Any other illness that, in the investigator's judgement, will substantially increase the risk associated with subject's participation in this study;
• Patients with history of type A adverse drug reaction, drug-associated anaphylaxis, idiopathic urticaria/anaphylaxis, mastocytosis, serum sickness, blistering skin eruption or acute interstitial nephritis;
• Patients where the allergy history was not able to be confirmed with patient;
• Patients on concurrent antihistamine therapy;
• Patients receiving more than stress dose steroids (i.e. > 50mg QID hydrocortisone [or steroid equivalent]).