What Does a SAAR Greater Than One Represent?
A Standardized Antimicrobial Administration Ratio (SAAR) greater than one indicates that antimicrobial use was higher than predicted based on risk-adjusted national benchmarks 1.
Understanding the SAAR Metric
The SAAR is an observed-to-predicted use ratio where:
- SAAR = 1: Observed antimicrobial use matches predicted use
- SAAR > 1: Antimicrobial use is higher than predicted (overuse relative to benchmark)
- SAAR < 1: Antimicrobial use is lower than predicted (underuse relative to benchmark)
The predicted use is calculated from statistical models that account for patient-level risk factors and facility characteristics, making this a risk-adjusted comparison 1.
Clinical Interpretation
When your facility has a SAAR > 1, this serves as a signal to investigate potential antimicrobial overuse and should prompt your antimicrobial stewardship program (ASP) to:
- Review prescribing patterns in the affected patient care locations
- Identify opportunities for targeted stewardship interventions
- Evaluate whether the excess use represents inappropriate prescribing or reflects legitimate differences in patient acuity not captured by the risk-adjustment model
The SAAR was developed by the CDC and endorsed by the National Quality Forum specifically to enable hospitals to track antimicrobial use over time and compare their data to national benchmarks 1. It uses point-of-care antimicrobial administration data reported as days of therapy per patient days present 1.
Practical Application
Studies demonstrate that SAARs can be effectively reduced through stewardship interventions. One multi-hospital system showed that transparent inter-facility SAAR comparisons motivated reductions from 1.09 to 0.83 for overall antimicrobial use 2. Another single-center study achieved SAAR values around 0.8 while maintaining stable or improved clinical outcomes 3.
Important caveat: The SAAR benchmark is based primarily on U.S. data through the National Healthcare Safety Network. When applied to hospitals in other countries like India, SAARs may be elevated (e.g., 1.49) due to different risk factor profiles and prescribing patterns, suggesting the need for region-specific risk adjustment 4.
The metric covers five antimicrobial categories including broad-spectrum agents for hospital-onset infections, community-acquired infections, anti-MRSA agents, surgical prophylaxis agents, and all antibiotics combined 1, 5.