Evaluation of piperacillin-tazobactam appropriateness and underlying drivers of inappropriate prescribing in a Belgian University Hospital: a retrospective study.

[en] BACKGROUND: Varying from 30% to 50% depending on the study, the high rate of inappropriate antimicrobial prescriptions is a major concern. These inappropriate prescriptions contribute to antibiotic resistance and associated morbidity and mortality. Prospective audit and feedback interventions is one of the core strategies recommended by the Infectious Diseases Society of America to improve antibiotic use. In line with this guidance, this approach was selected to evaluate piperacillin-tazobactam (PTZ) use within our institution.
METHODS: A prospective audit of PTZ prescribing was conducted over an 11-week period at the CHU of Liège. Prescriptions were reviewed weekly by an infectious diseases specialist and a clinical hospital pharmacist. The primary outcome was the appropriateness of PTZ prescriptions across three main evaluation criteria -indication, spectrum and duration- and one minor criterion -notification of the indication in the medical records-. The secondary outcome was to identify potential drivers of inappropriate prescribing. Interventions involved antibiotic discontinuation, de-escalation, oral step-down therapy and optimizing the pharmacokinetic and pharmacodynamic (PK/PD) profile.
RESULTS: Overall, 91.8% of the prescriptions were deemed appropriate for indication, 74.5% for spectrum, and 50% for duration. Notification was adequate in 65.5% of cases. However, most prescriptions were empirical (nearly 90%). Regarding stewardship interventions, broad-spectrum antibiotics were discontinued or de-escalated in 33.6% and 19.1% of cases, respectively, with intravenous-to-oral switch and PK/PD optimization suggested in 17.3% and 11.8% of cases. Our study identified several statistically significant determinants of inappropriate antibiotic use, including the type of care unit and the Charlson Comorbidity Index.
CONCLUSIONS: Our findings point out the role of an antimicrobial stewardship program in improving antibiotic use, especially in surgical units where inappropriate indication and poor notification were most common. Importantly, antibiotic treatment duration remains problematic across all hospital units. By linking patient characteristics to outcomes, our study identifies key drivers of inappropriate use, which could be further confirmed and refined in future research.