Clinical Outcome Associated With Beta‐Lactam Allergy Labels in Hospitalized Patients in Belgium

BACKGROUND: In the United States, beta-lactam allergy labels (BLAL) are documented in 9%-16% of hospitalized patients and associated with worse clinical outcomes such as increased mortality, length of hospital stay (LOS), intensive care unit (ICU) admission, and use of alternative antibiotics, providing an incentive for broad delabeling protocols. In Europe, BLAL prevalences are lower (0.6%-5%) and the association with clinical outcomes insufficiently explored. Therefore, we assessed the association between BLAL and penicillin allergy label (PenAL) and clinical outcomes and antibiotic use in hospitalized patients in Belgium. METHODS: Retrospective population-based cohort study of all patients admitted to the University Hospitals Leuven between 2010 and 2018 for pneumonia, pyelonephritis (therapeutic indications), or appendectomy, coronary artery bypass grafting, total knee or hip replacement (prophylactic indications) or heart, kidney, liver, or lung transplantation (mixed indications). Multivariable regression analysis was performed, using BLAL or PenAL as independent variable, and age, gender, Charlson Comorbidity Index, and diagnosis as a priori hypothesized confounders. RESULTS: We included 21,999 patients accounting for 23,842 admissions. A BLAL was recorded in 1394 (6.3%) patients, with 1113 (5.1%) having an unspecified PenAL. An increased use of next-line antibiotics was observed among patients with BLAL or PenAL. However, BLAL or PenAL were not associated with altered in-hospital or 3-month post-hospitalization mortality, LOS or ICU admission. CONCLUSION: Despite altered antibiotic use, we observed no association of BLAL or PenAL with clinical outcome parameters, highlighting regional differences and limiting transferability of non-EU findings to guide EU delabeling protocols.