Evaluation of a Pharmacist-Led Penicillin Allergy Assessment Program and Allergy Delabeling in a Tertiary Care Hospital.

Importance: Penicillin allergies are frequently mislabeled, which may contribute to use of less-preferred alternative antibiotics. Objective: To evaluate a pharmacist-led allergy assessment program's association with antimicrobial use and clinical outcomes. Design, Setting, and Participants: A pharmacist-led allergy assessment program was launched in 2 phases (June 1, 2015, and November 2, 2016) at a single-center tertiary referral hospital. The longitudinal cross-sectional study included all study period adult admissions; hospitalwide outcomes were assessed by segmented regression. Individual outcomes were assessed within an embedded propensity score-matched case-control study of inpatients undergoing comprehensive allergy assessment following self-report of penicillin allergy. Analysis occurred from March 1, 2020, to February 29, 2020. Exposures: The longitudinal study analyzed hospital-level outcomes over 3 periods: preintervention (15 months), phase 1 (structured allergy history alone, 16 months), and phase 2 (comprehensive assessment including penicillin skin testing, 52 months). The case-control study defined cases as individuals undergoing comprehensive allergy assessment. Main Outcomes and Measures: Hospital-level outcomes included antibiotic days of therapy per 1000 patient-days and hospital-acquired Clostridioides difficile infection (CDI) incidence per 10 000 patient-days. Individual outcomes included antibiotic selection, overall survival, and CDI-free survival. Results: Longitudinal analysis spanned 2014-2020 (median admissions, 46 416 per year; interquartile range [IQR], 46 001-50 091 per year). Hospitalwide, allergy histories were temporally associated with decreased use of nonpenicillin alternative antibiotics (rate ratio, 0.87; 95% CI, 0.79-0.97) and high-CDI-risk antibiotics (rate ratio, 0.91; 95% CI, 0.85-0.98). Penicillin skin testing was temporally associated with lower hospital-acquired CDI rates (rate ratio, 0.61; 95% CI, 0.43-0.86). The embedded case-control study included 272 cases and 819 controls. Median age was 63 years (interquartile range, 51-73 years), 553 (50.7%) patients were women, and 229 (21.0%) patients were Black. Allergy-assessed patients were less likely to receive high-CDI-risk antibiotics at discharge (odds ratio, 0.66; 95% CI, 0.44-0.98). Estimated reductions in mortality (hazard ratio, 0.77; 95% CI, 0.55-1.07) and hospital-acquired CDI risk (hazard ratio, 0.53; 95% CI, 0.18-1.55) were not statistically significant. Conclusions and Relevance: Pharmacist-led allergy assessments may be associated with reduced high-CDI-risk antibiotic use at both hospitalwide and individual levels. Although individual reductions in mortality and CDI risk did not achieve significance, divergence of survival curves suggest longer-term benefits of allergy delabeling warrant future study.

A prospective observational study of the effect of penicillin skin testing on antibiotic use in the intensive care unit.

BACKGROUND: Patients with penicillin allergy admitted to the intensive care unit (ICU) frequently receive non-beta-lactam antimicrobials for the treatment of infection. The use of these antimicrobials, more commonly vancomycin and fluoroquinolones, is associated with the emergence of multidrug-resistant infections. The penicillin skin test (PST) can help detect patients at risk of developing an immediate allergic reaction to penicillin and those patients with a negative PST may be able to use a penicillin antibiotic safely. METHODS: We determined the incidence of true penicillin allergy, the percentage of patients changed to a beta-lactam antimicrobial when the test was negative, the safety of the test, and the safety of administration of beta-lactam antimicrobials in patients with a negative test. Skin testing was performed using standard methodology. RESULTS: One hundred patients admitted to 4 ICUs were prospectively studied; 58 of them were male. The mean age was 63 years. Ninety-six patients had the PST: one was positive (1.04%), 10 (10.4%) were nondiagnostic, and 85 (88.5%) were negative. Of the 38 patients who received antimicrobials for therapeutic reasons, 31(81.5%) had the antibiotic changed to a beta-lactam antimicrobial after a negative reading versus 7 patients of the 57 (12%) who had received a prophylactic antimicrobial (P < .001). No adverse effects were reported after the PST or after antimicrobial administration. CONCLUSIONS: The PST is a safe, reliable, and effective strategy to reduce the use of non-beta-lactam antimicrobials in patients who are labeled as penicillin allergic and admitted to the ICU.