Are nosocomial infection rates in intensive care units useful benchmark parameters?

Background: The objectives of this study were to determine to what extent the German national nosocomial infection surveillance system (Krankenhaus Infektions Surveillance System, KISS) can take into account the circumstances prevailing in various intensive care units (ICUs) and to establish whether KISS-ICU infection rates can serve as useful benchmark parameters. Methods: The investigation focused on th ree major factors: microbiological monitoring, severity of illness and the duration of surveillance, For each of these factors separate infection rates were calculated for various ICU groups and the differences compared. Results: Significant differences were found for catheter-associated urinary tract infections (CAUTI) with routine monitoring, but not for ventilator-associated pneumonia (VAP). Significant differences were assessed for central venous catheter-associated bloodstream infections (CVCBSI), considering the average ventilator utilization rate in the ICU as a surrogate parameter for the average severity of illness in its patient group. Surveillance periods of about 1 year were necessary to confirm definite outlier and nonoutlier positions for the majority of the ICUs. Conclusion: Using KISS data for internal orientation, it is possible to note important differences between ICUs when interpreting infection rates; some initial examples of successful use of surveillance data for the reduction of infection rates are already available. However, the use of such data for external assessment is not possible, because external observers a re often unable to fully consider important factors in the interpretation of infection rates.