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New Quality Outcome Measures for Infection Prevention: Time for a Change?

The public reporting of quality of care outcome measures has become an inherent component of the national patient safety movement and performance on these measures can have significant financial and reputational consequences for healthcare organizations.

Healthcare-associated infection rates (HAIs), which are based almost exclusively on the manual surveillance conducted by infection preventionists (IPs) using standardized definitions and methods of the National Healthcare Safety Network (NHSN), are considered important measures for reporting. As this data is used for intra- and inter-hospital comparison of performance, there has been much interest in the accuracy and reliability of these rates, which are potentially biased due to the subjective nature of manual surveillance.

Several authors have determined that substantial differences do exist in the application of surveillance definitions and case-finding techniques by IPs. Based on these findings, the CDC is attempting to improve data reliability through funding of automated infection detection processes and state validation efforts, continual improvements in the NHSN application, and intensive educational offerings for IPs performing surveillance.

Two recent papers would suggest that efforts to improve the reliability of HAI quality outcome measures are shifting to the promotion and testing of newer performance metrics. Fakih et al.1 examine the current outcome measures used to evaluate catheter-associated urinary tract infection (CAUTI), noting that the NHSN surveillance definition is the most frequently used. The authors cite several limitations to the use of this definition, criteria and summary measure in evaluating outcomes:

  • Limited clinical correlation
  • Potential for underreporting of CAUTI events due to the subjective nature of manual surveillance
  • CAUTI events may be influenced by the prevalence of fever and the frequency of urine culture collection in a given location, both of which are elements of case-finding
  • Reliance on the use of catheter days, as the CAUTI rate denominator makes it challenging to measure the impact of quality improvement initiatives focused on catheter avoidance

They note that the interventions that have been most successful in reducing CAUTIs have focused on shortening catheter duration or avoiding catheterization. Therefore, the urinary catheter device utilization ratio (DUR), calculated by dividing the number of indwelling catheter-days by patient days on the same unit, is suggested as a performance measure. The DUR may be adjusted for variables currently reported to NHSN, including hospital demographics, such as size and teaching status, as well as unit type. Currently, the CDC is evaluating methods for DUR risk adjustment in an effort to develop a quality metric amenable to inter-hospital comparisons.

Rock and colleagues2 propose the replacement of central line-associated bloodstream infection (CLABSI) rates with hospital-onset bacteremia (HOB) rates as a new quality outcome measure. HOB is defined as a positive blood culture obtained greater than or equal to 48 hours after hospital admission. The authors state that HOB is “objective, simple to understand, easily automated, easier to collect, time saving, and is a more inclusive measure because it incorporates bacteremia as a result of any HAI and not just CLABSI.”

Monthly CLABSI and HOB rates for 2012 and 2013 from 80 ICUs were evaluated to assess the association between these two rates and the power of each measure to discriminate between ICUs using standardized infection ratios (SIRs) were compared. The authors concluded that a change in HOB rate is strongly associated with change in CLABSI rate and has greater power to discriminate between ICU performances. They state that consideration should be given to using HOB to replace CLABSI as an outcome measure in infection prevention quality assessments.

These papers offer insight into the current limitations of HAI outcome measures derived from potentially biased manual surveillance and offer alternative measures which are objective and amenable to automation with good discriminatory power for inter-facility comparisons. These measures will aid in ensuring a valid national HAI surveillance system for public reporting.


1 Fakih MG, Gould CV, Trautner BW, Meddings J, Olmsted RN, Krein, SL, and Saint S. Beyond Infection: Device Utilization Ratio as a Performance Measure for Urinary Catheter Harm. Infect Control Hosp Epidemiol. 2016;37(3):327-333.

2 Rock C, Thom KA, Harris AD, Li S, Morgan D, et al. A Multicenter Longitudinal Study of Hospital-Onset Bacteremia: Time for a New Quality Outcome Measure? Infect Control Hosp Epidemiol. 2016;37(2):143-148.

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