How to ‘SAVE’ antibiotics: effectiveness and sustainability of a new model of antibiotic stewardship intervention in the internal medicine area

Background: Antibiotic stewardship (AS) is a cornerstone of the fight against antimicrobial resistance. However, evidence on the best practice to improve antibiotic prescription in various hospital settings is still scarce. Aim of this study was to measure the efficacy of a non-restrictive AS intervention in the internal medicine area of a tertiary-care hospital across a three-year period. Methods: The intervention was composed of a three-month 'intensive phase' based on education and guidelines provision, followed by nine-month of audits-and-feedbacks activities. The primary outcome was the overall antibiotic consumption measured as Days-Of-Therapy (DOTs), Defined-Daily-Doses (DDDs). Secondary outcomes were carbapenems and fluoroquinolones consumption, all-cause in-hospital mortality, length-of-stay, incidence of Clostridioides difficile (CDIs) and carbapenem-resistant Enterobacterales bloodstream infections (CRE-BSIs). All outcomes were measured in the intervention wards comparing the pre- with the post- phase using an interrupted-time-series model. Results: A total of 145337 patient-days and 14159 admissions were included in the analysis. The intervention was associated with reduced DOTs*1000PDs (-162.2/P=0.005) and DDDs*1000PDs (-183.6/P=<0.001). A sustained decrease in ward-related antibiotic consumption was detected also during the post-intervention phase and in the carbapenems/fluoroquinolones classes. The intervention was associated with an immediate reduction in length-of-stay (-1.72 days/P<0.001) and all-cause mortality (-3.71 deaths*100 admissions/P=0.002) with a decreasing trend over time. Rates of CDIs and CRE-BSIs were not significantly impacted by the intervention. Conclusions: The AS intervention was effective and safe in decreasing antibiotic consumption and LOS in the internal medicine area. Enabling prescribers to judicious use of antimicrobials through active participation in AS initiatives is key to reach sustained results over time.