The long-term sustainability of a pharmacist-led antimicrobial stewardship penicillin allergy delabelling ward round: A prospective cohort study

<h2>Abstract</h2><h3>Objectives</h3> Inpatient penicillin allergy is associated with inappropriate antibiotic prescribing and adverse patient outcomes. We reviewed the long-term effectiveness, safety and antimicrobial stewardship impacts of a pharmacist-led penicillin allergy delabelling ward round. <h3>Methods</h3> Adult inpatients with a penicillin allergy label were evaluated during a pharmacist-led penicillin allergy ward round implemented within a tertiary referral health service in Melbourne, Australia for more than three years. Using the validated Antibiotic Allergy Assessment Tool (AAAT) and PEN-FAST clinical decision rule, patients with a low-risk penicillin allergy or PEN-FAST score <3, were offered a single-dose direct oral challenge. Inpatient antimicrobial prescribing was reviewed pre-allergy assessment, post-delabelling, and three months post-discharge. <h3>Results</h3> Between 21 January 2019 and 24 August 2022, 477 inpatients were reviewed. Direct oral challenge was effective, with 158/166 (95.2%) low-risk inpatients delabelled. One hundred eleven (23.2%) patients had a non-immune mediated penicillin allergy label and were directly delabelled. No serious adverse events occurred. Penicillin prescribing was increased during the index admission (OR 12.06, 95% CI [5.10–28.47]) and at three months post-intervention (OR 16.45, 95% CI [3.90–69.30]) for delabelled patients, compared with those not delabelled. <h3>Conclusions</h3> Inpatient penicillin allergy delabelling was deemed effective, safe and sustainable in a pharmacist-led program, with improved inpatient antimicrobial prescribing during the index admission and following discharge.