SIR Model Explorer

Return to 2022 NHSN HAI Rebaseline Home Page

Note: A similar tool for MRSA Bacteremia LabID is available: SIR Risk Factors (LabID)

The Standardized Infection Ratio (SIR) is a primary summary measure used by the National Healthcare Safety Network (NHSN) to track healthcare-associated infections (HAIs) in U.S. healthcare facilities. The SIR metric ­provides comparisons between the number of observed infections in a facility to the number that were “predicted” to have occurred if the facility had rates equal to the rate of the national 2022 baseline. The number of “predicted” infections is calculated using regression models, also known as risk adjustment models. Different risk adjustment models exist for each outcome type and facility type.

View information about the variables used in SIR calculations for surgical site infections (SSIs) under the 2022 baseline in the tables below. NHSN has three different model types available for SSI SIRs: the “Complex 30-day” model, the “All SSI” model, and the “Complex Admission/Readmission” model. Currently, only the “Complex 30-day” model is available in NHSN. Refer to NHSN’s Guide to the SIR (2022 baseline) for more information about this model type, the SIR metric, the calculation of the number of predicted SSIs, inclusion and exclusion criteria, and interpretation guidance.

Colon (COLO) Procedures, Complex 30-day Model

Abdominal Hysterectomy (HYST) Procedures, Complex 30-day Model