ABSTRACT
Background: Hong Kong experienced four epidemic waves caused by the ancestral strain of SARS-CoV-2 in 2020-2021 and a large Omicron wave in 2022. Few studies have assessed antibacterial drug prescribing for COVID-19 inpatients throughout the pandemic. Objectives: To describe inpatient antibacterial drug prescribing for COVID-19 patients throughout the pandemic and to determine factors associated with their prescription. Methods: This cohort study used electronic health records of COVID-19 cases admitted to public hospitals in Hong Kong from 21 January 2020 to 30 September 2022. We assessed the prevalence and rates of inpatient antibacterial drug use, using days of therapy/1000 patient days (DOT/1000PD), and examined the association of baseline factors and disease severity with receipt of an inpatient antibacterial drug prescription. Results: Among 65,810 inpatients, 54.0% were prescribed antibacterial drugs at a rate of 550.5 DOT/1000PD. Antibacterial use was lowest during wave 4 (28.0%; 246.9 DOT/1000PD), peaked in early wave 5 (64.6%; 661.2 DOT/1000PD), and then modestly declined in late wave 5 (43.2%; 464.1 DOT/1000PD) starting on 23 May 2022. Older age, increased disease severity, and residing in an elderly care home were strongly associated with increased odds of prescription, while receiving [≥] 2 doses of COVID-19 vaccines and pre-admission use of coronavirus antivirals were associated with lower odds. Conclusions: The rate of inpatient antibacterial prescribing initially declined during the pandemic, but increased during the Omicron wave when hospital capacity was overwhelmed. Despite the availability of COVID-19 vaccines and antiviral drugs, antibacterial drug use among COVID-19 inpatients remained high into late 2022.