Western Journal of Emergency Medicine: Integrating Emergency Care with Population Health

Introduction: Penicillin allergy is one of the most reported drug allergies, but studies have shown that patients who report an allergy frequently do not have a significant reaction when challenged. Avoidance of penicillin or beta-lactam antibiotics in these patients results in increased hospitalization costs, suboptimal antibiotic therapy, and risk for subsequent infection with multidrug resistant organisms. 

Methods: This was a single-center, retrospective chart review that included patients ≥ 18 years of age with documented penicillin allergy who presented to the emergency department (ED) over a one-year period. Clinical pharmacy specialists in the ED reviewed and stratified patient allergy risk. Patients with low-risk allergy histories who were to be admitted and gave formal consent were given an oral amoxicillin challenge and then observed in the ED for at least one hour. Patients who were eligible for challenge but were to be discharged from the ED were given the option to be seen in the allergy clinic. The primary outcome was the incidence of adverse reactions related to the oral amoxicillin challenge for patients. An exploratory secondary outcome was the average length of stay (LOS) in the ED for oral amoxicillin-challenged patients compared to the average LOS for non-oral amoxicillin-challenged patients. We performed descriptive statistics on all variables. 

Results: A total of 144 patients received an allergy assessment in the ED, 20 who received an oral amoxicillin challenge and 124 who did not. Baseline characteristics were similar in both groups. The average total LOS in the oral amoxicillin-challenged patients was a non-significant 36 minutes longer compared to the non-challenged patients (P = 0.4). Of 144 patients, 71 (49%) had their penicillin allergy removed as a result of the challenge.. One patient experienced a mild and self-limited reaction to the oral amoxicillin challenge (0.7%; 95% CI, 0.02-3.8%). 

Conclusion: An ED pharmacist-led, penicillin de-labeling protocol was safe and feasible. A secondary exploratory analysis showed no significant difference in length of stay between patients who received the oral amoxicillin challenge in the ED vs those who did not. Performing a proper penicillin allergy evaluation in the ED can have lasting benefits for patients and antimicrobial stewardship.