Evaluation of the Impact of Pharmacist-Led Penicillin Allergy Assessments on Antibiotic Utilization in a Large Community Teaching Hospital

Abstract

Rationale: Penicillins are the most common cause of allergic drug reactions with a prevalence of up to 20% in hospitalized patients. To date, there are limited Canadian publications describing pharmacist involvement in penicillin skin-testing. The purpose of this study is to evaluate the impact of a pharmacist-led initiative at Hôpital Montfort on de-labelling penicillin allergies and reducing the use of two broad spectrum antibiotics, meropenem and vancomycin. Objectives: To determine the proportion of patients in whom an antibiotic change was made as a result of a penicillin allergy assessment and identify barriers for not de-escalating therapy in patients deemed non penicillin allergic. Potentially drug cost savings were also examined for skin-tested patients. Methods: This is an observational cohort study conducted at Hôpital Montfort between October 1st 2016 and May 31st 2017, following the implementation of a policy allowing pharmacists to refer patients to an inpatient allergist for skin testing. Results: Pharmacists recommended a penicillin skin test (PST) for 15 of 32 identified patients (46.9%) with a penicillin allergy who were prescribed meropenem or vancomycin. Nine of 15 eligible patients (60%) underwent a PST, with five patients having their antimicrobial therapy de-escalated to a penicillin or cephalosporin antibiotic. Four patients had their therapy modified based only on the pharmacist assessment. De-escalation of therapy led to a range of cost saving between -$81.04 to $390.34 for patients switched to a penicillin or cephalosporin after PST.