Central Line-Associated Bloodstream Infection Standardized Infection Ratio

Healthcare-associated infections are infections that patients acquire during the course of receiving treatment for other conditions within a healthcare setting.

Data Source: National Healthcare Safety Network (NHSN)

Metrics Calculation

The Standardized Infection Ratio (SIR) is a ratio of the observed number of Central Line-Associated Blood Stream Infections (CLABSIs) as reported to CDC's National Healthcare Safety Network (NHSN) each year (i.e., 2009) to the predicted occurrence based on the rates of infections among all facilities reporting to NHSN during the referent period (January 2006 through December 2008). The CLABSI SIRs are adjusted for patient case-mix by taking in account the type and bed size of patient care locations and hospital affiliation with a medical school. For each hospital location, the number of CLABSIs that would be expected to occur can be predicted by multiplying the national pooled mean rates of CLABSI/1000 central-line days (from the referent period) for the specific type of patient care location under surveillance (e.g., small medical-surgical units from non-teaching facilities). The sum of the number of all CLABSIs that are predicted from each of the stratum of patient care locations is the total number of CLABSIs expected for the nation. This is compared statistically to the number actually observed among reporting facilities to calculate the SIR.

Additional Information

Inclusion Criteria: CLABSI data reported to NHSN from non-neonatal intensive care units and wards during 2009, among all 50 States, Washington, D.C., and Puerto Rico.

Exclusion Criteria: For the National Metric (summary measure), Neonatal Intensive Care Units are excluded.


This measure is calculated by the Division of Healthcare Quality Promotion, National Center for Emerging Zoonotic and Infectious Diseases, CDC, from the National Healthcare Safety Network (NHSN) Device Associated Module.

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Central Line-Associated Bloodstream Infection Standardized Infection Ratio