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 p0.05 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.