# PEN-DEL: implementing penicillin allergy de-labeling in hospitalized older adults – a quality improvement initiative

## TL;DR

This study shows that removing incorrect penicillin allergy labels in elderly hospitalized patients is safe and effective, improving antibiotic use.

## Contribution

A pharmacy-led initiative for penicillin allergy de-labeling in older adults using PEN-FAST scores and interdisciplinary collaboration.

## Key findings

- 71% of eligible patients were successfully de-labeled using oral amoxicillin challenge or information gathering.
- 42% of de-labeled patients received beta-lactam antibiotics safely within four weeks.
- Only one patient had a delayed reaction to amoxicillin-clavulanate.

## Abstract

Erroneously labeled penicillin allergies can lead to prolonged hospitalization, increased adverse effects and infection rates with alternative antibiotics. Although elderly patients are more vulnerable to these negative outcomes, penicillin allergy assessments and de-labeling remain underutilized in this population.

To assess the efficacy and challenges of implementing penicillin allergy de-labeling in hospitalized elderly patients.

Between March 2024 and April 2025, we conducted a quality improvement study on patients who were 65 years and older, had a penicillin allergy, and were admitted to Burnaby Hospital Acute Care for Elderly (ACE) Unit. Patients were proactively screened, interviewed, and assessed for eligibility in allergy de-labeling based on PEN-FAST score ≤1, predefined criteria, clinical judgment, and patient consent. If penicillin challenge was given, patients received pharmacist follow-up and 4-week outcomes were documented. A post-implementation survey was distributed to ward healthcare staff to identify barriers to implementation.

Out of 105 patients screened, 87 patients met study inclusion criteria. Among 34 patients deemed eligible for de-labeling, 24 patients (71%) were de-labeled from either oral amoxicillin challenge or information gathering alone. Within four weeks after de-labeling, 10 patients (42%) received beta-lactam antibiotics, and no patients received guideline-discordant broad-spectrum antibiotics. Only 1 patient experienced a delayed reaction to amoxicillin-clavulanate. From surveying ACE unit nursing, physician, and pharmacy staff, frequently reported barriers to allergy assessment and de-labeling included time and staffing constraints, and patient complexity.

Our pharmacy-driven interdisciplinary penicillin allergy de-labeling initiative is effective and safe for eligible hospitalized older adults with low PEN-FAST scores (≤1).