Antibiotic use in hospitalized patients with COVID-19: a population-based study in Hong Kong.

Background: Hong Kong experienced four epidemic waves caused by the ancestral strain of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in 2020-2021 and a large Omicron wave in 2022. Few studies have assessed antibacterial prescribing for coronavirus disease 2019 (COVID-19) inpatients throughout the pandemic. Objectives: To describe inpatient antibacterial prescribing and explore factors associated with their prescription. Methods: Electronic health records of patients with COVID-19 admitted to public hospitals in Hong Kong from 21 January 2020 to 30 September 2022 were used to assess the prevalence and rates of inpatient antibacterial drug use (days of therapy/1,000 patient days [DOT/1,000 PD]). We used multivariable logistic regression to investigate potential associations between patients' baseline characteristics and disease severity and prescription of an antibacterial drug during hospital admission. Results: Among 65,810 inpatients with COVID-19, 54.0% were prescribed antibacterial drugs (550.5 DOT/1,000 PD). Compared to waves 1-2 (46.7%; 246.9 DOT/1,000 PD), the prescriptions were lowest during wave 4 (28.0%; 246.9; odds ratio (OR): 0.39, 95% CI: 0.31-0.49) and peaked in early wave 5 (64.6%; 661.2; 0.82, 0.65-1.03). Older age (≥80 years: OR 2.66, 95% CI, 2.49-2.85; 60-79 years: 1.59, 1.51-1.69, compared with 20-59 years), more severe disease (fatal: 3.64, 3.2-4.16; critical: 2.56, 2.14-3.06, compared with severe), and COVID-19 vaccine doses (two doses: 0.74, 0.69-0.78; three doses: 0.69, 0.64-0.74; four doses: 0.52, 0.44-0.62, compared with unvaccinated) were associated with inpatient antibacterial drug use. Conclusions: Antibacterial prescribing changed over time for hospitalized patients with confirmed COVID-19 and was potentially related to patients' demographics, medical conditions, and COVID-19 vaccination status as well as healthcare capacity during epidemic waves.