Reproducibility of the surveillance effect to decrease nosocomial infection rates.

OBJECTIVE: To investigate whether the reduction effect due to participation in a nosocomial infection surveillance system for laboratory-confirmed central venous catheter (CVC)-associated primary bloodstream infection (BSI), ventilator-associated pneumonia (VAP), and surgical site infection (SSI) is reproducible for different time periods, independent of confounding factors that might occur during a specific time period.
METHODS: Data from the German national nosocomial infection surveillance system from the period January 1997 through June 2008 were used. CVC-associated BSI data and SSI data were analyzed for 3 starting periods, and VAP data were analyzed for 2 starting periods. Monthly infection rates were calculated for the following 36 months, and relative risks comparing the first and third surveillance years of each period were calculated.
RESULTS: A total of 2,399 CVC-associated BSI cases from 267 intensive care units, 3,637 VAP cases from 150 intensive care units, and 829 SSIs following 3 different procedures from 113 departments were analyzed. A significant reduction in VAP was shown for both starting periods investigated (overall relative risk [RR], 0.80 [95% CI, 0.74-0.86]). A significant reduction in CVC-associated BSI was demonstrated for 2 of 3 starting periods (overall RR, 0.83 [95% CI, 0.75-0.91]). A significant reduction in SSI was found for 2 starting periods for knee prosthesis insertion (overall RR, 0.56 [95% CI, 0.38-0.82]), for all of the 3 starting periods for cesarean delivery (overall RR, 0.75 [95% CI, 0.61-0.93]), and for none of the 3 starting periods for endoscopically performed cholecystectomy (overall RR, 0.89 [95% CI, 0.62-1.27]).
CONCLUSIONS: The surveillance effect, manifest as a significant reduction of nosocomial infection rates between the first and third years of participation in a surveillance system, was observed independently from the calendar year in which the surveillance activities started.