The Effectiveness of a Hospital-Based Antimicrobial Stewardship Program: A Three-Year Observational Study

Objective: The aim of the study was to evaluate the impact of a policy-driven Antimicrobial Stewardship Program (AMSP) on antibiotic consumption, prescribing compliance, infection control, resistance trends, and clinical outcomes in a tertiary care hospital in India over a 3-year period.

A retrospective cross-sectional study compared pre-AMS (nurse-led) and post-AMS (multidisciplinary) phases (2022-2025). Indicators included antibiotic use, defined daily doses (DDD), days of therapy (DOT), policy compliance, resistance rates, and clinical outcomes. Statistical significance was set at p < 0.05.

Overall antibiotic use decreased, with DDD/1,000 patient-days declining from 2,599.3 to 2,413.3 with p = 0.974>0.05 and DOT from 1,474.4 to 1,394.6 with p = 0.991>0.05. Policy compliance rose marginally (78%-80%; p = 0.412) but declined in the second post-AMS year. De-escalation improved initially (46%-80.3%) but later dropped to 65.2%. Surgical prophylaxis agent selection improved (88%-94%; p = 0.044), while duration adherence remained low. Resistance rates for vancomycin-resistant Enterococcus and CRE decreased (44%-26% and 47%-42%, respectively) without statistical significance. Standardized mortality ratio (SMR) declined (1.28-0.62; p < 0.001), but all-cause mortality slightly increased (3.54%-3.63%). Readmissions (60.7-126.5/1,000 discharges) and intensive care unit (ICU) transfers (0.319-0.381/1,000 admissions) rose post-AMS.

AMSP implementation was associated with process improvements and favourable trends in resistance and SMR, but most changes were not statistically significant. Increased readmissions, ICU transfers, and inconsistent compliance highlight the need for sustained interventions and patient-level risk adjustment.