The role of the neutrophil Fcγ receptor I (CD64) index in diagnosing spontaneous bacterial peritonitis in cirrhotic patients

Objective: To investigate the role of the neutrophil Fcγ receptor I (CD64) index in the diagnosis of spontaneous bacterial peritonitis (SBP) in cirrhotic patients.

Methods: A total of 123 cirrhotic patients with ascites who fulfilled the inclusion criteria were enrolled in this study. Ascites and blood samples were collected; the polymorphonuclear neutrophil (PMN) count, bacterial culture, and related laboratory tests were performed. The CD64 index was determined for each sample using flow cytometry.

Results: The neutrophil CD64 index results were significantly higher in cirrhotic patients with SBP than in those without SBP (p<0.001). There was a positive correlation between the neutrophil CD64 index and the PMN count in ascites. In the receiver operating characteristic curve (ROC) analysis, the area under the curve (AUC) was 0.894 (95% confidence interval 0.823-0.964, p<0.001). The optimal cut-off value for the neutrophil CD64 index was 2.02. The sensitivity and specificity of the neutrophil CD64 index for cirrhotic patients with SBP were 80.49% and 93.90%, respectively. The elevated neutrophil CD64 index was down-regulated by antibiotic therapy (p=0.002).

Conclusions: The neutrophil CD64 index could be used as a sensitive and specific indicator for the diagnosis of SBP in cirrhotic patients with ascites and is also modulated by antibiotic therapy.