The diagnostic value of different pro-inflammatory factor in early diagnosis of sepsis in patients with bloodstream infection

Abstract

To investigate the expression of different inflammatory variables, such as procalcitonin (PCT), C-reactive protein (CRP), and endotoxin in septic patients with bacterial bloodstream infection, in order to assess the value of these variables in early diagnosis. The clinical data of 132 bacterial bloodstream infection patients with clinical diagnosis of sepsis in intensive care unit (ICU) of Beijing Shijitan Hospital of Capital Medical University from February 2012 to May 2013 were analyzed retrospectively. Patients were divided into Gram-negative (G(-)) bacterial bloodstream infection group (n=98) and Gram-positive (G(+)) bacterial bloodstream infection group (n=34) according to the result of blood culture. The inflammatory variables including white blood cell (WBC) count, percentage of neutrophils (N), CRP, PCT and level of endotoxin in blood of both groups within 6 hours of bloodstream infection were compared, and their correlation was analyzed. The receiver operating characteristic (ROC) curve of inflammatory variables for the diagnosis of bloodstream infection was plotted, and their diagnostic value for bloodstream infection was evaluated according to area under ROC curve (AUC), and finally the sensitivity and specificity of inflammatory variables for bloodstream infection were assessed based on the best diagnostic cut-off points. (1) The levels of the variables, including PCT, CRP, and endotoxin content in the G(-) bacterial bloodstream infection group were significantly higher than that of G(+) bacterial bloodstream infection group [PCT: 5.11 (0.99, 18.00) μg/L vs. 1.00 (0.36, 2.73) μg/L, Z=49.647, P=0.000; CRP: 111.5±57.4 mg/L vs. 75.9±56.6 mg/L, t=9.947, P=0.000; endotoxin: 18.00 (8.75, 28.00) ng/L vs. 5.00 (5.00, 6.25) ng/L, Z=52.333, P=0.000]. There was no significant difference in WBC and N between two groups. (2) The results of the correlation coefficient of the inflammatory variables showed: in G(-) bacterial bloodstream infection group positive correlation was found between PCT and CRP (r=0.671, P=0.000), PCT and endotoxin (r=0.916, P=0.000), CRP and endotoxin (r=0.687, P=0.004). On the other hand, in G(+) bacterial bloodstream infection group, correlation was shown between PCT and CRP (r=0.620, P=0.000), PCT and endotoxin (r=0.487, P=0.010), PCT and WBC (r=0.537, P=0.001), PCT and N (r=0.432, P=0.011), CRP and endotoxin (r=0.674, P=0.000), endotoxin and WBC (r=0.197, P=0.024). In all of bloodstream infection patients positive correlation was found between PCT and CRP (r=0.538, P=0.000), PCT and endotoxin (r=0.740, P=0.000), PCT and WBC (r=0.259, P=0.003), CRP and endotoxin (r=0.579, P=0.000), endotoxin and WBC (r=0.197, P=0.024). (3) The ROC curve in patients with the diagnosis of sepsis due to bloodstream infection showed that: in the G(-) bacterial bloodstream infection group, AUC for PCT was 0.825, sensitivity of 71.4% and specificity of 96.2% with the best cut-off value >2.455 μg/L; AUC for CRP was 0.761, sensitivity of 64.3% and specificity of 80.8% with the best cut-off value >79.45 mg/L; AUC for endotoxin was 0.797, sensitivity of 61.2% and specificity of 94.2% with the best cut-off value >15.5 ng/L. In the G(+) bacterial bloodstream infection group, AUC for PCT was 0.619, sensitivity of 41.2% and specificity of 82.7% with the best cut-off value >1.585 μg/L; AUC for CRP was 0.533, sensitivity of 32.4% and specificity of 82.7% with the best cut-off value >95.25 mg/L. The concentrations of PCT, CRP, and endotoxin in patients with G(-) bacterial bloodstream infection were significantly higher than those of G(+) bacterial bloodstream infection group. They are valuable for the early diagnosis of bloodstream infection, and judgment of its severity, and it is more valuable with the combination of PCT, CRP, and endotoxin concentration determinations.