Improving Antimicrobial Treatment in Terms of Antimicrobial Stewardship and Health Costs by an Opat Service a Single Centre Prospective Cohort Study

Abstract

Purpose: Outpatient parenteral antimicrobial therapy (OPAT) is a standard for antimicrobial therapy internationally. With this prospective cohort study, we aimed to assess the impact of an OPAT service as part of antimicrobial stewardship (ABS) and evaluate the safety and efficiency of the program while illuminating the financial benefit for the hospital. Methods: Socio-demographic data, treatment regimen and outcomes were prospectively recorded for all patients assigned to the program of the OPAT unit of the University Hospital of Zurich between November 2018 and September 2022. Results: In total, we recorded 303 OPAT assignments of which 260 resulted in effective OPAT episodes. The 260 OPAT episodes were further optimized towards the choice of antimicrobial substance (n=18) and length of therapy (n=6). Moreover, OPAT resulted in alteration of patient assessment and care led by ABS strategies in 247 of 260 episodes (95%). While the bed days saved per year increased consistently with time, a total of 3934 in-hospital treatment days were saved amounting to a cost saving of 9’835’000 CHF over 47 months. Adverse events were recorded in 46 cases whilst only two of these have been the reason for readmission during OPAT treatment. Clinical cure was noted in 77% (199/260) and was negatively associated with Charlson Comorbidity Index (CCI; OR per 1 unit higher 0.85 (95% CI 0.78-0.93)). Conclusion: This study demonstrates the impact of an OPAT service in the framework of ABS as well as its benefits for the hospital whilst preserving safety and efficacy for the patient’s parenteral antimicrobial treatment.