Paving the Path Forward: 2015 Rebaseline
A comprehensive guide to NHSN’s SIR, including risk factors used in the SIR calculations under the 2015 baseline.
Frequently asked questions about definition changes, the SIR, and the 2015 rebaseline
NHSN collects and analyzes healthcare-associated infections (HAI) data reported from across the nation to help track HAI incidence, identify opportunities to eliminate HAIs, and measure the progress of HAI prevention efforts. Progress is measured using a summary statistic called the standardized infection ratio (SIR). This comparative metric is calculated after risk adjusting the data reported into NHSN. State and national progress is presented each year in CDC’s HAI Progress Report. In this report, the SIRs are adjusted for risk factors that can impact the number of infections reported by a hospital, such as type of patient care location, bed size of the hospital, patient age, and other factors.
Healthcare facilities may report the following HAI types into NHSN:
- Central line-associated bloodstream infections (CLABSIs)
- Catheter-associated urinary tract infections (CAUTIs)
- Surgical site infections (SSIs)
- Hospital-onset Clostridium difficile (C. difficile)
- Hospital-onset methicillin-resistant Staphylococcus aureus (MRSA) bacteremia (bloodstream infections)
CDC uses reported HAI data to calculate the SIR for each reporting state and facility. The SIR compares the number of infections in a facility or state to the number of infections that were “predicted”, or would be expected, to have occurred based on previous years of reported data (i.e., baseline data). The number of predicted infections is an estimate based on aggregated data reported to CDC’s NHSN during a specific baseline period. The current risk adjustment methods and baseline periods vary by HAI type and/or healthcare facility type.
“Rebaseline” is a term that CDC’s National Healthcare Safety Network (NHSN) staff is using to describe updates to original HAI baselines. The 2015 rebaseline updates both the source of aggregate data and the risk adjustment methodology used to create the original baselines. Risk adjustment refers to the processes used to account for the differences in risk that may impact the number of infections reported by a hospital, such as type of patient care location, bed size of the hospital or patient age. When the data are risk-adjusted, it makes it possible to fairly compare hospital performance. In this report, the SIRs are adjusted for risk factors.
Previously calculated SIRs had different baseline years for each infection type and facility type. Beginning with 2015 data, HAI prevention progress will be measured in comparison to infection data reported to NHSN using updated risk-adjustment models. SIRs using the 2015 baselines will be available in NHSN on January 7, 2017.
|HAI Type||Original National Baseline Data||2015 Rebaseline|
|Acute Care Hospitals (ACH)||Long-term Acute Care Hospitals (LTACH)||Inpatient Rehabilitation Facilities (IRF)|
|SSIs||2006-2008||None||None||2015 (ACH only)|
|Hospital-onset C. difficile||2010-2011||None||None||2015|
|Hospital-onset MRSA bacteremia||2010-2011||None||None||2015|
|Ventilator-associated events (VAE)||New – No Previous National Baseline Data||2015|
|Mucosal Barrier Injury (MBI)||2015|
|Standardized Utilization Ratio (SUR) (all device types)||2015|
What can hospitals and other organizations expect to happen to their SIRs after the 2015 rebaseline?
The data included in the 2015 baseline will serve as a new “reference point” for comparing progress. CDC expects that hospital SIRs will increase and shift closer to 1, especially for SIRs that will be calculated for 2015.
- General FAQ [PDF – 117K]
- Timeline FAQ [PDF – 81K]
- CLABSI FAQ [PDF – 57K]
- CAUTI FAQ [PDF – 75K]
- SSI FAQ [PDF – 59K]
- Laboratory-identified C. difficile and MRSA bacteremia FAQ [PDF – 73K]
- 2015 Rebaseline SIR Changes Applicable to CMS QRP [PDF – 125K]
- Verification of Hospital Compare/Quality Net Data: CLABSI Example [PDF – 694K]
- Verification of Hospital Compare/Quality Net Data: SSI Example [PDF – 777K]
- New! Introduction to the NHSN Re-baseline – March 2017
- New! The NHSN Re-Baseline: In Depth – March 2017
- NHSN Rebaseline Webinar, Part 1 – October 2016 [Video – 74 minutes]
- NHSN Rebaseline Webinar, Part 2 – November 2016 [Video – 86 minutes]
- Updating the national risk-adjustment of HAI Data – March 2016 [Video – 59 minutes]
- December 2015 NHSN Newsletter [PDF – 2M]– information included in FAQs
- March 2016 NHSN Newsletter [PDF – 2M]– information included in FAQs
- June 2016 NHSN Newsletter [PDF – 966K]– information included in FAQs
- CDC’s HAI Progress Report FAQs
- Page last reviewed: April 5, 2017
- Page last updated: June 5, 2017
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