1820. Indirect Standardization: A Convenient Benchmarking Approach to Antibiotic Utilization Based on Patient Mix

Background Antimicrobial stewardship programs are recommended to risk-adjust antimicrobial use in order to support intra- and inter-hospital comparisons. The purpose of our investigation was to evaluate a benchmarking strategy for its ability to accurately identify changes in risk-adjusted utilization as a result of known stewardship interventions. Methods Antimicrobial drug use was measured as days of therapy (DOT) from billing records. Based on diagnosis-related group (DRG) assignment, we calculated expected (E) use determined by indirect standardization and compared with observed (O) use for three targeted groups of antimicrobials: anti-pseudomonals β-lactams; ceftriaxone; and fluoroquinolones. As a stewardship strategy, a clinical pharmacist-driven, individualized pseudomonal risk assessment based antibiotic prior authorization process was implemented in the third quarter of 2016, focusing on commonly encountered community-onset infections. Results The 10-month time period prior to implementing the intervention was used to establish the benchmark with over 10,000 billing records. Utilization assigned to DRGs from this time period was used to predict expected utilization. As a result of the intervention, a decrease in anti-pseudomonal agent utilization at the cost of an increase in ceftriaxone utilization was observed (Figure 1), with the lack of a significant impact toward change in the utilization of the fluoroquinolones. Variability in use is explained by the treated patients within each DRG. Conclusion Antibiotic utilization was benchmarked to expected use adjusted for patient mix based on DRGs, and trends in changing antibiotic consumption were correctly identified. Differences between expected and observed use reflect usage patterns that take into consideration type of patients treated and provides the basis of evaluation of outcome measures for our stewardship interventions.Figure 1. O/E Ratios (95% CI) Calculated for the 12 Month Time Period Following Implementation of the Intervention. Disclosures All authors: No reported disclosures.