Impact of the introduction of the national antimicrobial stewardship standard across Queensland Health hospitals: ecological observational study exploring patterns of antimicrobial use.

Background: Antimicrobial stewardship programmes are a critical tool for addressing the rising threat of antimicrobial resistance.

Aim: To determine changes in patterns of antimicrobial use in Queensland public hospitals following introduction of the National Safety and Quality Health Service antimicrobial stewardship standard.

Methods: A retrospective pre/post intervention study was conducted across Queensland public hospitals at the ecological level using Queensland Health's MedTRx database. An interrupted time-series analysis was performed using linear regression models to determine rates of antimicrobial use by quarterly aggregated defined daily dose per 1000 patient-days, for groups of hospitals stratified by peer group classification. Pre-defined time-periods for antimicrobial stewardship programme implementation in response to the introduction of the standard were analysed.

Findings: In the post-intervention period, there was a decrease in overall use of systemic antimicrobials, glycopeptides, carbapenems and fluoroquinolones in principal referral and public acute group A hospitals. A decrease in overall use was also observed for smaller regional and remote public acute group C and D hospitals; however, increases in glycopeptide and fluoroquinolone use were observed. Third-generation cephalosporin use was unchanged for all hospital peer groups. The proportion of overall use that was accounted for by narrow-spectrum penicillin was low for all facilities, with modest improvements in the post-intervention period observed in principal referral facilities only.

Conclusion: These findings add to current knowledge on the effectiveness of legislative quality standards on antimicrobial stewardship at the macro level and highlight gaps to target for future programmes.