Abstract: Objective The aim of this study was to assess the clinical relevance significance of simultaneous detection of peripheral blood amyloid A (SAA), WBC/PLT ratio, cluster of differentiation 64 (CD64) and ascitic fluid CD64 in patients diagnosed with liver cirrhosis and spontaneous bacterial peritonitis (SBP). Methods Between January 2021 and December 2022, 106 patients diagnosed with liver cirrhosis and ascites were admitted to our hospital . They were divided into two groups: the SBP group (49 cases) and non-SBP group (57 cases), based on the presence or absence of SBP. Additionally, 50 healthy subjects comprised the control group. Peripheral blood SAA levels were quantified using immunoturbidimetry. WBC and PLT were assessed using a fully automatic blood analyzer. Peripheral blood CD64 and ascites CD64 levels were measured via fully automated flow cytometry. Comparative analyses of peripheral blood SAA, WBC/PLT ratios, and CD64 leves, both in blood and ascitic fluid were conducted across the three groups. The diagnostic efficacy of of peripheral blood SAA, WBC/PLT ratios, CD64 leves(both blood and ascitic fluid), individually and in combination, for identifying liver cirrhosis complicated by SBP was evaluated using receiver operating characteristic(ROC) curves. Results In the SBP group, peripheral blood SAA, WBC/PLT ratio, CD64, and ascites CD64 levels were (82.3±17.2) mg/mL, (0.4±0.2), (13126.3±90.1) mol/cell and (14912.8±101.7) mol/cell, respectively, which were significantly higher than those in the non-SBP group [(11.2±3.4) mg/mL, (0.1±0.1), (1083.9±61.4) mol/cell and (936.2±51.1) mol/cell, P<0.05] .SAA, WBC/PLT ration, and CD64 levels in the peripheral blood of the SBP group were also significantly elevated compared to the control group [(10.6±2.8) mg/mL, (0.1±0.1) and (1063.7±57.5) mol/cell, P<0.05]. However, no significant differences were observed in SAA, WBC/PLT ratio, and CD64 levels in peripheral blood between the SBP group and the control group (P>0.05). Following treatment, peripheral blood SAA, WBC/PLT ratio, CD64 and ascites CD64 levels in the SBP group decreased to (35.6±6.9) mg/mL, (0.3±0.1), (3302.4±70.5) mol/cell and (4758.4±78.6) mol/cell, respectively, which were significantly lower than those before treatment (P<0.05). ROC curve analysis demonstrated that the combined sensitivity of SAA, WBC/PLT ratio, CD64 and ascites CD64 in diagnosing cirrhosis and SBP was 96.00%, with an AUC of 0.930, which was significantly higher than that of individual detections (P<0.05). Conclusion Elevated levels of peripheral blood SAA, WBC/PLT ratio, CD64, and ascites CD64 are observed in patients with liver cirrhosis and SBP. The combined detection of these markers holds significant diagnostic value for identifying and managing liver cirrhosis complicated by SBP.

Key words: Liver cirrhosis, SBP, Amyloid A, White blood cell count/platelet count, Cluster of differentiation 64