RESULTS: 1) A total of 21 studies with a total of 6007 patients were included. Elevated procalcitonin level was a risk factor for death in community-acquired pneumonia (CAP) (RR 4.38, 95% CI 2.98-6.43), particularly in patients with a low CURB-65 score. The commonly used cut-off, 0.5ng/ml, had low sensitivity and was not able to identify patients at high risk of dying. The procalcitonin assay with a functional sensitivity < 0.1 ng/ml was necessary to predict mortality in CAP clinically. The prognostic performance was almost equally restricted to patients suffering from VAP and CAP. 2) An elevated PCT level and PCT non-clearance was associated with a higher risk of death in sepsis. The pooled relative risk (RR) was 2.60 (95% confidence interval (CI), 2.05-3.30) and 3.05 (95% CI, 2.35-3.95), respectively. Initial PCT values were of limited prognostic value in patients with sepsis. PCT non-clearance was a prognostic factor of death in patients with sepsis.