Abstract Purpose Approximately 10% of US patients report a penicillin allergy, yet fewer than 1% have a true immunoglobulin E–mediated reaction. Mislabeled allergies contribute to unnecessary use of broad-spectrum antibiotics, increasing healthcare costs, hospital stays, antimicrobial resistance, and mortality. Despite guideline recommendations for risk stratification and allergy delabeling, implementation remains limited. PEN-FAST is a validated clinical tool used to facilitate delabeling without resource-intensive skin testing. This study aimed to determine the prevalence of low-risk penicillin allergy among adult patients using the PEN-FAST tool within a pharmacist-led medication reconciliation process. Methods A multicenter, retrospective prevalence study was conducted at 2 community hospitals. Patients admitted or seen in the emergency department from September 16 through December 16, 2024, with a documented penicillin allergy who underwent a pharmacist-performed PEN-FAST assessment were included. The primary outcome was the proportion of patients classified as having low-risk penicillin allergy (PEN-FAST score of 3). Secondary outcomes included allergy delabeling rates and the frequency of direct oral penicillin challenges. Descriptive analysis was used to evaluate the results. Results Of 95 patients assessed, 74% (n = 70) were classified as low risk. Among these low-risk patients, 10% (n = 7) had their allergy label removed and 3% (n = 2) underwent a direct oral penicillin challenge, with both tolerating penicillin without adverse reactions. Conclusion These findings suggest that pharmacist-led PEN-FAST implementation is a feasible strategy to identify low-risk penicillin allergies, but allergy delabeling and oral challenge rates remain low. Further efforts are needed to integrate PEN-FAST into clinical workflows and enhance antimicrobial stewardship.
Linville et al. (Fri,) studied this question.