Comparative analysis of Australian hospital antimicrobial utilization, using the WHO AWaRe classification system and the adapted Australian Priority Antimicrobial List (PAL)

BACKGROUND: In 2020 the Australian Priority Antibacterial List (PAL) was developed to support national surveillance of antibacterial usage. OBJECTIVES: To compare the WHO AwaRe classification system with the Australian PAL to analyse antibacterial utilization in Australian acute care hospitals. METHODS: Monthly antibacterial usage rates (defined daily dose per 1000 occupied bed days) were calculated using pharmacy dispensing records together with patient occupancy data for all acute care hospitals contributing to the National Antimicrobial Utilisation Surveillance Program for 2015–19. Annual usage rates as a proportion were determined using the WHO AWaRe and Australian PAL categorization systems. RESULTS: In 2019, 70.0% of total-hospital aggregate antibacterial use in Australian acute-care hospitals fell into the WHO Access category, with 29.4% of usage in Watch and 0.6% in the Reserve category. Analysis using the PAL classification system showed 40.1% of hospital usage fell into the Access category, 55.6% in Curb and 3.8% in the Contain categories. On average, cefazolin usage comprised 12.5% of acute hospital usage. CONCLUSIONS: Cefazolin, a first-line agent for surgical prophylaxis in Australia, was identified as a key antibacterial driving the differing results seen between the two classification systems. Data on the proportions of day surgery relative to inpatient surgical cases would assist the accuracy of benchmarking usage between hospitals using the PAL categorization system. The use of a targeted, nationally approved prioritized classification system can provide a focus for antimicrobial stewardship at a national level, however a clear understanding of the consumption metric used, as well as its limitations, are required for interpretation.