Application of serum SAA, CRP, PCT, WBC and N% in the diagnosis of neonatal septicemia

Abstract

To explore the application value of SAA (serum amyloid A), CRP (C reactive protein), PCT (procalcitonin), WBC (white blood cell) and N% (neutrophil %) in the diagnosis of neonatal septicemia. This study was a retrospective study. 173 children with clinically diagnosed septicemia and 66 children with definitely diagnosed septicemia admitted to the Department of Neonatology, the Affiliated Changsha Central Hospital, Hengyang Medical School, University of South China,from January 2022 to January 2024 were selected as the case group, and 148 children with neonatal jaundice who were hospitalized during the same period were selected as the control group. Fasting venous blood was collected within 24 hours after the children's admission to detect the levels of serum WBC, N%, SAA, CRP and PCT. One-way analysis of variance and Kruskal-Wallis H test were used to compare the general data and inflammatory index levels of the three groups of children. The correlation analysis between SAA and other inflammatory indicators was conducted using Spearman correlation analysis. The receiver operating characteristic (ROC) curve was used to determine the diagnostic efficacy of different inflammatory indicators for patients with definitely diagnosed septicemia and those with clinically diagnosed septicemia, and for those with clinically diagnosed septicemia and those without infection. The results showed that the levels of WBC [(16.88±5.64)×109/L], N% [70.00 (63.00, 75.00)], PCT [2.22 (1.20, 5.55) mg/L], CRP [3.00 (0.50, 10.30) mg/L], SAA [19.70 (10.82, 49.90) mg/L] in the clinically diagnosed septicemia group and WBC [(16.10±7.48)×109/L], N% [73.50 (61.50, 80.93)], PCT [5.35 (0.69, 20.07) mg/L], CRP [15.52 (4.98, 30.50) mg/L], SAA [43.95 (14.00, 175.98) mg/L] in the definitely diagnosed septicemia group were all higher than those in the control group (11.17±3.38)×109/L, 49.81 (36.93, 62.75), 0.20 (0.07, 0.99) mg/L, 0.54 (0.20, 1.40) mg/L, 5.15 (3.60, 8.68) mg/L, and the differences were all statistically significant (all P<0.05). Spearman correlation analysis showed that the level of SAA was positively correlated with WBC, N%, PCT and CRP (rs=0.453, 0.540, 0.343, 0.550, all P<0.05). ROC curve analysis showed that the area under ROC curve(AUC) of SAA for the definitely diagnosed septicemia group and the clinically diagnosed septicemia group was higher than that of other inflammatory indicators, among them, the AUC of SAA for diagnosing the definitely diagnosed neonatal septicemia group was 0.933 (95%CI: 0.809-1.000, P<0.05), with a sensitivity of 92.90% and a specificity of 99.30%. The AUC of SAA for diagnosing the clinically diagnosed septicemia group was 0.861 (95%CI: 0.818-0.904, P<0.05), with a sensitivity of 83.20% and a specificity of 81.80%. In conclusion, compared with CRP, PCT, WBC and N%, SAA has higher sensitivity and specificity for distinguishing neonatal septicemia (including definitely diagnosed septicemia and clinically diagnosed septicemia), and has certain auxiliary diagnostic value for neonatal septicemia.