Abstract: Objective To investigate the clinical value of C-reactive protein (CRP)/albumin (CAR) and CD4⁺T cell /CD8⁺ T cell ratio (CD4⁺/CD8⁺) in evaluating the severity and prognosis of infectious mononucleosis (IM) complicated with liver damage.Methods 130 children with IM liver injury from July 2020 to March 2022 were selected, and their liver function examination was abnormal. They were divided into liver injury group (n=86) and non-liver injury group (n=34). According to the degree of liver damage, the children in the liver damage group were divided into mild liver damage group (n=34), moderate liver damage group (n=30) and severe liver damage group (n=22), and according to the peak load of EBV-DNA, they were divided into low load group (n=14), moderate load group (n=57) and high load group (n=15). Fifty children who received physical examination in our hospital during the same period were included in the health group. The expression levels of CAR and CD4⁺/CD8⁺ in each group were observed. Pearson analysis was conducted for correlation with TBA, IgM and APACHE II scores. Receiver operating characteristic curve (ROC) was plotted to analyze the evaluation efficacy of combined and separate tests.Results CAR of liver injury group was 0.83±0.21, higher than 0.62±0.14 and 0.35±0.09, CD4⁺/CD8⁺ of liver injury group was 0.85±0.31, lower than 1.04±0.36 and 1.32±0.45, respectively. The difference was statistically significant (F=24.387, 19.482, both P<0.05). In the observation group, CAR was 0.92±0.27 and 0.87±0.25 in the severe liver injury group and the high EBV DNA load group, which were higher than 0.84±0.22 and 0.71±0.16 in the moderate and mild groups, and 0.79±0.18 and 0.65±0.13 in the moderate and low load groups, respectively. CD4⁺/CD8⁺ was 0.89±0.31 and 0.78±0.29 in the severe and high load groups, lower than 1.07±0.38 and 1.23±0.43 in the moderate and mild load groups, and 1.13±0.42 and 1.25±0.51 in the medium and low load groups. The differences were statistically significant (F=15.296, 24.387, 28.453, 26.591, all P<0.05). CAR in the observation group was 0.83±0.21 in acute phase, higher than 0.54±0.13 in rehabilitation phase, CD4⁺/CD8⁺ was 1.06±0.37 in acute phase, lower than 1.28±0.42 in rehabilitation phase, the difference was statistically significant (t=8.265, 7.483, all P<0.05). Pearson showed that CAR was positively correlated with TBA, IgM and APACHE II scores, while CD4⁺/CD8⁺ was negatively correlated (P<0.01). ROC showed that the AUC of CAR and CD4⁺/CD8⁺ tests alone and in combination were 0.794, 0.758 and 0.916, respectively, and the combined detection efficiency was higher than that of any single test (P<0.01).Conclusion Serum CAR and CD4⁺/CD8⁺ levels were significantly correlated with the severity and prognosis of patients with IM liver injury, and combined detection was of high clinical value.

Key words: IM, Liver damage, CAR, CD4⁺/CD8⁺, Assessed value