Multicenter prospective study of procalcitonin as an indicator of sepsis

The clinical significance of serum procalcitonin (PCT) for discriminating between bacterial infectious disease and nonbacterial infectious disease (such as systemic inflammatory response syndrome (SIRS)), was compared with the significance of endotoxin, β-D-glucan, interleukin (IL)-6, and C-reactive protein (CRP) in a multicenter prospective study. The concentrations of PCT in patients with systemic bacterial infection and those with localized bacterial infection were significantly higher than the concentrations in patients with nonbacterial infection or noninfectious diseases. In addition, PCT, endotoxin, IL-6, and CRP concentrations were significantly higher in patients with bacterial infectious disease than in those with nonbacterial infectious disease (P < 0.001, P < 0.005, P < 0.001, and P < 0.001, respectively). The cutoff value of PCT for the discrimination of bacterial and nonbacterial infectious diseases was determined to be 0.5 ng/ml, which was associated with a sensitivity of 64.4% and specificity of 86.0%. Areas under the receiver operating characteristic curves (POCs) were 0.84 for PCT, 0.60 for endotoxin, 0.77 for IL-6, and 0.78 for CRP in the combined group of patients with bacterial infectious disease and those with nonbacterial infectious disease, and the area under the ROC for PCT was significantly higher than that for endotoxin (P < 0.001). In patients diagnosed with bacteremia based on clinical findings, the positive rate of diagnosis with PCT was 70.2%, while that of blood culture was 42.6%. PCT is thus essential for discriminating bacterial infection from SIRS, and is superior in this respect to conventional serum markers and blood culture.