Beta-Lactam Allergy Assessment And Management Service: a Pharmacist-led Approach

Background: Inaccurate allergy labeling results in inappropriate antimicrobial management of the patient, which may affect clinical outcome, increase the risk of adverse events, and increase costs. Inappropriate use of alternative antibiotics has implications for antimicrobial stewardship programs, and microbial resistance. As part of an antimicrobial stewardship program there is scope for a pharmacist-led program promoting appropriate antimicrobial allergy labeling through history and directed testing and challenge.

Methods: A specialist pharmacist identified all adult in-patients labeled as penicillin allergic, consented for the study and screened them for eligibility. The pharmacist took an accurate allergy and medication history. If deemed appropriate and safe an oral challenge was performed or the patient was referred to an Immunology clinic. All patients included in the study were followed-up one year after intervention.

Results: 250 eligible patients were identified as labeled as penicillin allergic. The prevalence of reported penicillin allergy at our hospital was 8.06%. We found that 79.6% of patients could be delabeled in our study population. Of those, 80.4% were delabelled after consultation with a specialsit pharmacist, 15.6% had an uneventful oral challenge, and 4% were deemed inappropriately labelled after referral to the Immunology clinic. The patients who were deemed to be appropriately labeled accounted for 20.4% of the study population. These patients had longer length of stays (8.6 vs. 6.5 days), more ICU admissions (11/51 vs. 1/199 admissions) and were prescribed more courses of antibiotics in the community (4.8 vs. 2.6 courses). The cost associated with treating penicillin allergic labeled patients is 2.8 times greater in the community and 4 times more in the hospital setting. Changes in antibiotic therapy were recommended in132 (66.3%) delabeled patients, of which 97.7% had no adverse events after commencing on a penicillin antibiotic. At the one-year follow-up, 84.2% of patients who were delabeled had no adverse events to repeated administration of penicillin antibiotics.

Conclusion: This study showed that a pharmacist-led allergy management service is a safe and cost effective option to promote appropriate antimicrobial prescribing and play an integral role in antimicrobial stewardship.