NHSN analyst outlines SAAR, highlights rise in 2023 AU reporting and portal tools

Haley Koslik, a public health analyst on the NHSN AUR team, led a training session explaining the Standardized Antimicrobial Administration Ratio (SAAR), the NHSN Antimicrobial Use (AU) Option Report and how to navigate the Antimicrobial Resistance and Patient Safety Portal.

The SAAR "is the Standardized Antimicrobial Administration Ratio," Koslik said, describing it as "a standardized metric of antimicrobial use...calculated by dividing observed antimicrobial days by predicted antimicrobial days." She said hospitals use the SAAR to track antimicrobial use over time, compare with national benchmarks and evaluate stewardship interventions.

Koslik explained the SAAR is built from a referent baseline year of NHSN AU data and that NHSN periodically "rebaselines" models to expand eligible location types and improve prediction precision. She outlined eligible location types (17 total across adult, pediatric and neonatal baselines) and cautioned that facility-wide inpatient and many outpatient acute care settings are not currently SAAR eligible.

The analyst described the AU Option Report as a one-year summary for acute care hospitals reporting at least nine months of SAAR-eligible data. The report includes a PDF executive summary (median and pooled mean SAARs, percentage AU by antimicrobial class and drug, and best-practice discussion) plus Excel data tables with detailed distributions and characteristics of reporting hospitals.

Highlighting 2023 changes, Koslik said the AU report showed a steady increase in reporting: roughly 1,200 facilities reported nine or more months of data in 2019 versus a little over 2,400 by the end of 2023; adult ward locations reported rose from about 4,000 in 2019 to about 7,100 in 2023. She added that as of Jan. 1, 2024, 3,236 facilities had reported at least one month of AU data and that jurisdiction participation ranged from 13% (Puerto Rico) to 76% (Maine).

Koslik noted multiple factors can affect year-to-year SAAR comparisons — including the COVID-19 pandemic, shifts in prescribing and hospital composition, antimicrobial availability and disease activity — and cautioned that visual comparisons may not indicate statistically significant or clinically meaningful changes. She offered a concrete example: higher broad-spectrum antibacterial agents predominantly used for community-acquired infections (BSCA) SAARs among pediatric ICUs and wards in 2023 were partly explained by increased use of beta-lactam/beta-lactamase inhibitor agents (amoxicillin–clavulanate and ampicillin–sulbactam) during a late‑2022 amoxicillin shortage and a respiratory-illness surge.

Koslik said increased enrollment in the AU option likely reflects, in part, the Centers for Medicare & Medicaid Services final rule for the Medicare Promoting Interoperability Program, which made the AUR surveillance measure a requirement for 2024 under the public health and clinical data exchange objective; she emphasized the mandate did not change the 2023 reporting period but likely encouraged enrollment.

She also explained state display rules in the report: percentile data are omitted for states with fewer than 10 reporting facilities; states with 10–19 facilities show only median values; states with at least 20 facilities display full distributions. Koslik listed states that crossed the 20-facility threshold in 2023 (adults: Arizona, Connecticut, Kansas, New Mexico, Nevada; neonates: Pennsylvania), enabling fuller state-level percentiles.

Demonstrating the Antimicrobial Resistance and Patient Safety Portal, Koslik showed users how to navigate from the portal homepage to Antibiotic Use → Inpatient Antibiotic Use → All SAAR Agent Categories, use the left-hand navigation to toggle year and population, and hover over maps to view state participation counts, eligible facilities and median SAARs with confidence intervals. She noted the AUR module does not currently provide antimicrobial resistance data to the portal; resistance data are derived from HAI and other sources.

Koslik closed with resource links (NHSN guide to the SAAR, AUR module reports including the 2023 report, and the patient safety portal inpatient antibiotic use page) and contact options (post in the annual training community, submit through ServiceNow for users with a SAMS account, or email NHSN@cdc.gov).