Trends in ventilator-associated pneumonia rates within the German nosocomial infection surveillance system (KISS)

OBJECTIVE. To investigate trends in ventilator- associated pneumonia ( VAP) rates during participation in the German nosocomial infection surveillance system ( Krankenhaus- Infektions- Surveillance- System [ KISS]). METHODS. A total of 71 ICUs that began participating in KISS in 1999 or later and continued participation for at least 36 months were selected. Beginning with the first month of participation, the pooled mean rate of VAP in the ICUs was calculated for each year of participation. The incidence densities for the 3 years of participation were compared using the Pearson chi(2) test. Relative risks ( RRs) and 95% confidence intervals ( CIs) were calculated. VAP rates were calculated for each ICU and year of participation, and rates for years 1 and 3 were compared using the Wilcoxon test for paired samples. RESULTS. Twenty- nine medical- surgical, 18 medical, 20 surgical, 2 neurosurgical, and 2 pediatric ICUs met the selection criteria. Surveillance data were available on 181,275 patients, for whom there were 613,098 patient- days and 224,138 ventilator- days. A total of 2,043 cases of VAP were reported. The ICUs had a pooled VAP rate of 10.5 cases per 1,000 ventilator- days during year 1 of KISS surveillance. In year 2, the rate decreased by 19%, to 8.7 cases per 1,000 ventilator- days ( RR, 0.81 [ 95% CI, 0.73- 0.90]). In year 3, the rate decreased by 24% from year 1, to 8.0 cases per 1,000 ventilator- days ( RR, 0.76; 95% CI, 0.68- 0.85). Both results were significant (P<.001 by the Pearson x 2 test). Comparison of the VAP rates of the ICUs did not show a significant difference between years 1 and 3 of KISS participation. CONCLUSION. Surveillance was associated with a significant reduction in the pooled rate of VAP during years 1- 3 of KISS participation.