Impact of timing in prospective audit and feedback on broad-spectrum antibiotic use: a comparison between third-day and seventh-day interventions.

Prospective audit and feedback (PAF) is a key component of antimicrobial stewardship (AS) programs and has been shown to reduce the use of broad-spectrum antibiotics. However, the optimal timing of PAF intervention remains unclear. This quasi-experimental, single-center study investigated the impact of changing PAF timing from day 3 to day 7 after initiating empirical broad-spectrum antibiotics. Monthly days of therapy (DOT) for carbapenems (CAR), piperacillin-tazobactam (PIP/TAZ), and cefepime (PEF) were extracted from 2016 to 2024. Annual susceptibility rates of Pseudomonas aeruginosa and the time from blood culture submission to susceptibility results were also evaluated. Interrupted time series analysis assessed changes in DOT, while other data were descriptively analyzed. DOT for CAR and PIP/TAZ decreased significantly post-intervention (CAR: -0.68, P < 0.001; PIP/TAZ: -0.29, P = 0.031), despite no significant change in trend slopes. PEF showed no significant changes. Susceptibility rates of P. aeruginosa remained stable. Notably, 28.3 % of blood culture results exceeded 4 days to report, and 95 % were available by day 7. As causality cannot be inferred from this observational design, the mechanism underlying the observed reduction in DOT remains uncertain. Nevertheless, adjusting PAF timing may be feasible in settings with limited stewardship resources. Further studies are needed to determine the most effective timing of PAF interventions and to assess generalizability to other institutions.