Association Between the Neutrophil-to-Lymphocyte Ratio and Severity of Liver Injury in Children With Kawasaki Disease

Aims/Background: Kawasaki disease (KD) is an acute febrile illness characterized by rash in children. The disease can cause liver damage, and severe cases can affect the growth and development of children. This study aimed to explore the correlation between the neutrophil-to-lymphocyte ratio (NLR) and the severity of liver function injury in KD. Methods: A total of 123 children with KD admitted to the Affiliated Yangming Hospital of Ningbo University from September 2022 to September 2025 were selected and divided into a normal liver function group (normal group) and an abnormal liver function group (abnormal group) according to the presence of liver function injury. Routine blood and liver function indices were assessed in children with KD. According to alanine aminotransferase (ALT) levels, the children in the abnormal group were further divided into three groups: mild, moderate, and severe. Routine blood and liver function indices were compared among the three groups. Multivariate logistic regression analysis was performed to identify independent risk factors for liver function impairment in children with KD. The correlations between NLR and C-reactive protein (CRP) and liver function indices were analyzed using Spearman’s correlation. A sensitivity analysis was also performed using ALT as the upper limit of normal pediatric sex-specific values. Results: The levels of neutrophils, NLR, and procalcitonin (PCT) in the abnormal group were significantly higher than those in the normal group (p < 0.05), while lymphocyte levels were significantly lower (p < 0.05). Among the 123 children with KD, 47 had liver function impairment, with higher aspartate aminotransferase (AST), ALT, and total bilirubin (TBIL) levels. The comparison of NLR among the three groups was statistically significant, and NLR increased with increasing severity and liver function injury (p < 0.05). After adjusting for potential confounding factors, including age, CRP, intravenous immunoglobulin (IVIG) response, and coronary artery lesions, NLR remained an independent risk factor for liver function impairment in children with KD (p < 0.05). NLR was positively correlated with AST, ALT, Gamma-Glutamyl Transferase (GGT) and TBIL (p < 0.05). Receiver operating characteristic (ROC) curve analysis showed that NLR achieved an area under the curve (AUC) of 0.664 (95% confidence interval (CI): 0.574–0.747) for identifying children with KD and liver function impairment, with an optimal cutoff value of 4.702 (sensitivity, 46.8%; specificity, 82.9%). Conclusion: NLR is significantly associated with the severity of liver function impairment in children with KD. As an indicator readily obtained from routine blood tests, NLR may help clinicians identify children at increased risk of liver function injury.