Laila M Castellino

Background Outpatient parenteral antimicrobial therapy (OPAT) is a safe and cost-effective transitional care approach administered via different delivery models. No standards exist for appropriate OPAT program staffing. We examined outcomes of patients receiving OPAT via different care models to identify strategies to improve safety while reducing healthcare overuse. Methods Retrospective demographic, clinical and outcome data of a cohort of patients discharged on OPAT reviewed in two times (April to June 2021 and January to March 2022), when staffing changed, and stratified by care model: Self-administered OPAT, healthcare-OPAT, and skilled nursing facility-OPAT. Results Of 342 patients included, 186 (54%) received OPAT in 2021, 156 (46%) received OPAT in 2022. Hospital length of stay increased from 12.4 to 14.3 days in 2022. In a Cox proportional hazards regression model, visits to the emergency department (ED) within 30-days of OPAT initiation (HR 1.76, 95% CI 1.13-2.73, p = 0.01) and readmissions (HR 2.34, 95% CI 1.22-4.49, p = 0.01) increased in 2022 compared to 2021, corresponding to decreases in OPAT team staffing. Increased readmissions in the 2022 cohort were for reasons unrelated to OPAT (p = 0.01) while readmissions related to OPAT did not increase (p = 0.08). Conclusion In a well-established OPAT program, increased healthcare utilization - length of stay, ED visits, and readmissions, were seen during periods of increased staff turnover and attrition. Rather than blunt metrics such as ED visits and readmissions which are influenced by multiple factors besides OPAT, our findings suggest the need to develop OPAT-specific outcome measures as a quality assessment tool, and to establish optimal OPAT program staffing ratios.