# Patterns of antimicrobial use among hospitalized Veterans with and without a penicillin-class allergy

## TL;DR

This study examines how often Veterans with a penicillin allergy label receive different antibiotics and finds that antibiotic use patterns are becoming more similar between those with and without the allergy label.

## Contribution

The study provides updated evidence on the impact of penicillin allergy labels on antibiotic prescribing trends in hospitalized Veterans.

## Key findings

- The prevalence of penicillin-class allergies on admission decreased from 12.99% to 11.20% between 2011 and 2022.
- Use of certain antibiotics like cefazolin increased regardless of allergy status, while others like aztreonam decreased.
- Prescribing differences are decreasing except for aminoglycosides, clindamycin, and fluoroquinolones.

## Abstract

To explore the progress that the Veterans Health Administration has made to minimize the impact of the penicillin (PCN) allergy label, we determined the proportion of Veterans who reported a PCN-class allergy at the time of hospitalization and described antibiotic use in hospitalizations with and without a PCN-class allergy.

Cross-sectional study.

National sample of 6,541,299 acute care admissions between 2011 and 2022.

We calculated the prevalence of PCN-class allergies on admission and used Poisson regression to compare patterns of antibiotic use between hospitalizations with and without a PCN-class allergy.

The prevalence of PCN-class allergies on admission decreased from 12.99% to 11.20%. Use of cefazolin and non-pseudomonal third-generation cephalosporins increased regardless of PCN-class allergy status (“PCN-class allergy only” +11.46%, “No antibiotic allergy” +4.92%). The prevalence ratio (PR) for antibiotic use in hospitalizations with a PCN-class allergy compared to hospitalizations without antibiotic allergies, decreased for anti-Methicillin Resistant Staphylococcus aureus agents (1.26 [1.25, 1.28] to 1.15 [1.13, 1.17]), carbapenems (1.59 [1.54, 1.65] to 1.47 [1.41, 1.53]), and aztreonam (23.89 [22.45, 25.43] to 17.57 [15.90, 19.42]); and increased for fluoroquinolones (1.58 [1.56, 1.60] to 2.15 [2.09, 2.20]).

Prevalence of PCN-class allergies is declining and narrow-spectrum βL use is rising among hospitalized Veterans. Prescribing differences are decreasing between hospitalizations with and without a reported PCN-class allergy, except for aminoglycosides, clindamycin, and fluoroquinolones. These findings can serve to identify areas of focus for future analyses or interventions related to the impact of the PCN allergy label on antibiotic selection.