The overall 28-day mortality rate was 18.3% (n = 32) and the median ICU length of stay (LOS) was 16 (9 to 28.5) days (range 1 to 142 days). The 28-day mortality was higher in patients with severe CAP compared with those with HAP or VAP (36.8% vs. 10.5% and 8.2%, respectively, P < 0.01 each). Likewise, the maximum degree of organ dysfunction as assessed by the maximum SOFA score was higher in CAP compared with HAP and VAP patients. PCT levels were consistently higher in non-survivors than survivors throughout the observation period ( Figure 2 ). Initial PCT values of VAP patients were significantly higher in non-survivors than in survivors with a median PCT of 0.6 ng/ml in the latter group (Figure 3) . This difference between survivors and non-survivors was also observed in HAP but did not reach statistical significance. In the survivors, PCT values dropped to a median of 50.0% (27.3 to 100.0%) of the baseline value (P < 0.001) during the first five study days. A drop of similar magnitude with 53.7% (27.6 to 148.0%) was observed in the non-survivors without reaching statistical significance (P = 0.08). Initial and maximal PCT levels correlated with maximum SOFA score (r 2 = 0. 51 and r 2 = 0.57, respectively). The association between initial and maximum PCT levels and SOFA score was independent of the type of pneumonia (Figure 4) . In a ROC analysis on discrimination of 28-day mortality, the area under the curves (AUC) for maximum PCT, initial PCT, and admission-day APACHE II score were 0.74, 0.70, and 0.69, respectively ( Figure 5 ). The AUCs were not statistically different. The best cut-off of initial PCT to predict 28-day mortality was 1.1 ng/ml (odds ratio 7.0 (95% CI 2.6 to 25.2)) and that of the maximum PCT was 7.8 ng/ ml (odds ratio 5.7 (95% CI 2.5 to 13.1)). The highest AUC was observed in VAP patients with 0.71 (95% CI 0.92 to 1.01) compared to CAP with 0.41 (95% CI 0.24 to 0.92) and HAP with 0.56 (95% CI 0.58 to 0.96).