2025 Southeastern Residency Conference

Title: Pharmacist Driven Penicillin Allergy De-escalation using the PEN-FAST Allergy Decision Rule
Authors: Ny'Asia Cleckley, Molly Thompson, Jessica Sutton
Background: 
β-lactam allergies, specifically allergies to penicillin, are the most commonly reported antibiotic medication allergies in the hospital setting. However, according to the American Academy of Asthma, Allergy, and Immunology (AAAAI) Joint Task Force, 90% of patients with a reported penicillin allergy are able to tolerate the penicillin drug class.
The PEN-FAST penicillin allergy assessment is a clinical decision-making tool designed to be a quick and low burden method to identify patients with low-risk penicillin allergies who would likely have a negative result if formal penicillin allergy testing was conducted. The mnemonic PEN-FAST describes the risk score of true penicillin allergy based on the following queries: five years or fewer since the reaction (2 points), anaphylaxis/angioedema or severe cutaneous adverse reaction (SCAR) (2 points), and treatment required for the reaction (1 point).  Trubiano et al (2020) validated the PEN-FAST assessment with results showing it to have a high negative predictive value of 96.3% in scores less than 3 points, coinciding with the cutoff for low risk penicillin allergies.  
Methods: A single-center, retrospective, cohort analysis conducted on adult (>18 years old) patients with a documented penicillin allergy admitted to Trident Medical Center from February 2025 to April 2025. The study is pending exempt review by the health system’s Institutional Review Board. Eligible patients included non-pregnant adults with a penicillin allergy documented in electronic medical record (EMR) who were screened during an admission within the defined timeframe using the PEN-FAST assessment. Patients were excluded from the study if there was a documented allergic reaction of anaphylaxis (throat/mouth swelling, trouble breathing) or SCAR to penicillin in the EMR or were unable/unwilling to participate in the interview. The primary outcome of this study is the incidence of patients with a PEN-FAST score less than 3 points correlating with low risk of true penicillin allergy. Secondary outcomes include penicillin allergy de-labeling, post-screening oral amoxicillin challenge, antibiotic selection, antibiotic-associated adverse events and the time required for patient interview. The patients’ electronic medical record will be used to collect data on patient demographics, PEN-FAST screening result, antibiotic selection, antibiotic-associated adverse events and use of a post-documentation amoxicillin oral challenge.
Results: In progress
Conclusion: In progress