Effect of an educational antimicrobial stewardship programme on antibiotic prescriptions' appropriateness in three medical units of a large university hospital: an interrupted time series analysis

Background: Antimicrobial stewardship (AMS) programmes aim to enhance antibiotic prescription quality, reduce antibiotic use, and combat multi-drug-resistant pathogens. However, the optimal AMS intervention for different clinical settings remains unclear, with previous studies predominantly focusing on antibiotic consumption rather than prescription appropriateness. Aim: This study aimed to evaluate the impact of an education-based AMS intervention on antibiotic prescription appropriateness in three medical units of a 1500-bed university hospital. Methods: We conducted a retrospective interventional, interrupted time series study, to test the effect of an educational programme in three medical units of our 1500-bed university hospital in Rome, from June 2018 to October 2019. The intervention comprised six educational meetings held over 3 months (December 2018 to February 2019). The primary outcome was the appropriateness of antibiotic prescriptions, with in-hospital survival as a secondary outcome. Findings: Of 609 antibiotic prescriptions evaluated, the programme led to a significant and sustained reduction in inappropriate prescriptions in one unit (change in level: -18.15%, P<0.01; change in trend: -3.21%, P=0.01), while it failed to demonstrate a significant reduction in the other two units and globally in the three units. Conclusion: The same educational AMS programme led to variable results in terms of antibiotic appropriateness in three medical units with similar structural and organizational features. Larger and more tailored high-quality AMS interventional studies are needed to better understand the impact of educational programmes on the appropriateness of antibiotic prescriptions.