2158. Introducing the Population Standardized Infection Ratio (SIR): A Metric that Marries the Device SIR to the Standardized Utilization Ratio (SUR)
Session: Poster Abstract Session: Healthcare Epidemiology: HAI Surveillance
Saturday, October 6, 2018
Room: S Poster Hall
  • Population Standardized Infection Ratio-final-no crops.pdf (341.3 kB)
  • Background: The device standardized infection ratio (SIR) has been used to compare units’ and hospitals’ performance for different publicly reported infections. Interventions to reduce unnecessary device use may select a higher risk population that is not accounted for in the current risk adjustments, leading to a paradoxical increase in SIR for facilities that may be high performers. The standardized utilization ratio (SUR) adjusts for device use for different units and facilities.

    Methods: We calculated the device SIR (calculated based on actual device-days) and population SIR (defined as Σ Observed events/ Σ Predicted events based on predicted device days) accounting for the facility SUR for both central line-associated bloodstream infections (CLABSI) and catheter-associated urinary tract infections (CAUTI) in 84 hospitals from a single system. The observed and predicted events were compiled at the unit-level and aggregated to facility and system-level SIRs for calendar years 2016 and 2017.

    Results: The central line SUR was 1.02 for 801,737 central line-days, with the device SIR of 0.78 and the Population SIR of 0.80 (+2.6%, relative increase). On the other hand, the urinary catheter SUR was 0.89 for 758,966 urinary catheter-days, with the device SIR of 0.87 and the Population SIR of 0.77 (-11.5%, relative decrease). The cumulative attributable difference for CAUTI with a SIR of 1 was -107 for the device SIR compared to -185 for the population SIR (73% increase in events prevented). Facilities with a wider variation in SUR tended to have a greater difference in device versus population SIRs (Figures 1 and 2).

    Conclusion: Population SIR takes into account device utilization, making it an attractive metric to address overall risk of infection or harm to a patient population, and reduces the risk of selection bias that may impact the device SIR with interventions to reduce device use.

     Figure 1: Population and Device SIR Difference vs. SUR Away from 1 (CLABSI) (SIR Difference of Zero not Shown)

    Figure 2: Population and Device SIR Difference vs. SUR Away from 1 (CAUTI) (SIR Difference of Zero not Shown)


    Mohamad Fakih, MD, MPH1, Ren-Huai Huang, PhD2, Angelo Bufalino, PhD2, Lisa Sturm, MPH1, Ann Hendrich, PhD, RN1 and Ziad Haydar, MD, MBA1, (1)Care Excellence, Ascension Healthcare, St. Louis, MO, (2)Ascension Clinical Research Institute, Ascension Healthcare, St. Louis, MO


    M. Fakih, None

    R. H. Huang, None

    A. Bufalino, None

    L. Sturm, None

    A. Hendrich, None

    Z. Haydar, None

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