Partial Economic Evaluation and Clinical Impact of a Stewardship Quality-Improvement Intervention to Reduce Intravenous Antibiotic Duration: A Quasi-Experimental Study.

OBJECTIVES: Surgical site and community-acquired osteoarticular infections cause prolonged hospitalization, high costs, and health system burden. Although early intravenous-to-oral (IV-to-PO) antibiotic switch is internationally established, adoption remains limited in Brazil. OBJECTIVE: To evaluate the effectiveness and direct medical costs of a structured IV-to-PO switch protocol targeting ≤5 days of IV therapy for these infections. METHODS: Quasi-experimental before-after study in a public tertiary hospital in southern Brazil. Microbiologically confirmed adult patients were included in retrospective control (January-October 2023; n = 60) or prospective intervention cohort (December 2023-May 2024; n = 29) after protocol implementation by infectious disease specialists and clinical pharmacists. PRIMARY OUTCOME: therapeutic success (clinical improvement, declining inflammatory markers, oral tolerance). Antimicrobial costs were estimated from public health system perspective using microcosting (2024 Brazilian reais [BRL]). RESULTS: Median hospital length of stay decreased from 12 days (IQR 8-17) to 8 days (IQR 6-13; P = .019). IV antibiotic duration was halved-from 10 days (IQR 7-14) to 5 days (IQR 4-8; P < .001), with increased oral use (P = .007). Therapeutic success was numerically higher in the intervention group (88.9% vs 71.7%; P = .140). Median antimicrobial costs declined from BRL 707.32 (IQR 438.25-1141.92) to BRL 351.40 (IQR 193.82-588.34; P < .001). A 4-day stay reduction may yield significant savings because bed-days are the primary cost of complex infections in public health system. CONCLUSIONS: A structured ≤5-day IV-to-PO protocol in a Brazilian public hospital safely reduced stays and costs without compromising outcomes, supporting stewardship in resource-constrained settings. Future studies should include hospital bed-day costs beyond antimicrobial expenses.