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

Objective: 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 three-year period. Subject and Methods: A retrospective cross-sectional study compared pre-AMS (nurse-led) and post-AMS (multidisciplinary) phases (2022–2025). Indicators included antibiotic use defined dailydoses (DDD), days of therapy (DOT), policy compliance, resistance rates, and clinical outcomes. Statistical significance was set at p<0.05. Results: Overall antibiotic use decreased, with DDD/1000 patient-days declining from 2599.3 to 2413.3 with p=0.974>0.05 and DOT from 1474.4 to 1394.6 with p=0.991>0.05. Policy compliance rose marginally (78% to80%; p=0.412) but declined in the second post-AMS year. De-escalation improved initially (46% to80.3%) but later dropped to 65.2%. Surgical prophylaxis agent selection improved (88% to 94%; p=0.044), while duration adherence remained low. Resistance rates for VRE and CRE decreased (44% to26% and 47% to42%, respectively) without statistical significance. SMR declined (1.28 to0.62; p<0.001), but all-cause mortality slightly increased (3.54% to 3.63%). Readmissions (60.7 to126.5/1000 discharges) and ICU transfers (0.319 to 0.381/1000 admissions) rose post-AMS. Conclusion: AMSP implementation was associated with process improvements and favourable trends in resistance and SMR, but most changes were not statistically significant. Increased re-admissions, ICU transfers, and inconsistent compliance highlight the need for sustained interventions and patient-level risk adjustment.