Epidemiology of penicillin allergy labels in a general Swedish population

Background: Penicillin allergy prevalence is reported in up to 10% of patients and is linked to broad-spectrum antibiotic overuse, extended hospitalizations, and higher mortality. Its prevalence has not previously been evaluated in Sweden. Objective: The aim of this study was to investigate the prevalence and characteristics of penicillin allergy labels (PALs) in the electronic medical records of 3 Swedish regions (1,088,000 inhabitants). Methods: A retrospective analysis of PALs in the electronic medical records in the Southeast Healthcare Region of Sweden and estimation of point prevalence were performed. Two nonoverlapping cohorts were defined by label complexity: a simple cohort with pre-2017, nonstandardized labels identified by keywords (n = 7,514), and a complex cohort (n = 22,736) with post-2017, standardized labels identified using Anatomical Therapeutic Chemical codes. Conclusion: Overall, 2.8% of the study population carried a PAL. Labels need to be better documented: Up to two thirds lacked sufficient information to determine the phenotype and other characteristics of the reactions. Moreover, antimicrobial resistance was more prevalent among patients with a PAL.