Daniel M. Saman, Kevin T. Kavanagh, Said K. Abusalem

The derivations of the standardized infection ratio (SIR) are reviewed in this report. To be most understandable to the consumer, the SIR National Benchmark of 1.0 should reflect what is obtainable.The SIR is a tool intended to be used by consumers in value purchasing to compare differences between facilities and thus should not adjust for these differences. Ideally, factors used in risk adjustment should solely be based upon patient characteristics. Thus, facility-specific adjustments (i.e., medical school affiliation, major teaching institution and unit bed size) should be used with caution in calculating the SIR and their use made clearly transparent to health-care consumers.Using data downloaded from the US Department of Health and Human Services' website, Hospital Compare, we observed an average SIR for central line blood stream infections of 0.568 and an SIR at the peak of the distribution curve approximating 0.35. A suggested methodology to calculate an obtainable SIR is to set the National Benchmark of 1.0 at the location of the distribution curve's peak. The curve's peak is more reflective of higher performing facilities. The SIR needs to reflect the expected performance of facilities, which are using up-to-date methods of infection control. The remainder of the facility SIRs can then be adjusted accordingly.It is recommended that the obtainable SIR be calculated every other year using data from the most recent 3 years. This enables the SIR to be reset as the control of health care-associated infections progressively improves.