Abstract: Objective To explore the relationship between blood copper-zinc ratio and cognitive impairment (CI) in maintenance hemodialysis (MHD) patients.  Methods A total of 130 MHD patients treated in the hemodialysis center of Huai'an Hospital Affiliated to Xuzhou Medical University between March 2022 and September 2023 were enrolled in this study. Their clinical data were collected. Based on the Montreal Cognitive Assessment (MoCA) score, the patients were divided into CI group (n=55) and normal cognitive group (n=75). Inductively coupled plasma mass spectrometry was used to measure blood zinc and copper levels. Baseline clinical and laboratory data were compared between the two groups. The correlation between copper-zinc ratio and MoCA score, the independent influence factors for the presence of CI, and the predictive value of copper-zinc ratio for CI in MHD patients were analyzed.  Results  Compared to the normal cognitive group, patients in the CI group had older age (t=-6.161, P<0.001), higher percentage of diabetics (c2=4.240, P=0.039), longer dialysis age (Z=-2.131, P=0.033), and higher levels of high sensitivity C-reactive protein (Z=-2.691, P=0.007), blood copper (Z=-4.272, P<0.001) and copper-zinc ratio (Z=-5.539, P<0.001), less years of education (Z=-4.227, P<0.001), and lower levels of creatinine (t=2.002, P=0.047), hemoglobin (t=5.948, P<0.001), albumin (Z=-5.519, P<0.001) and blood zinc (t=4.872, P<0.001). Spearman correlation analysis showed a negative correlation between MoCA score and the blood copper-zinc ratio (r=-0.509, P<0.001). Multivariate logistic regression analysis found that copper-zinc ratio (OR=1.449, 95% CI: 1.017～1.344) and age (OR=1.068, 95% CI: 1.002～1.138) were the independent risk factors for CI in MHD patients, while albumin (OR=0.746, 95% CI: 0.616～0.904) and hemoglobin (OR=0.945, 95% CI: 0.906～0.987) were the independent protective factors for CI (P<0.05). ROC curve analysis showed that the area under the curve of the copper-zinc ratio for predicting the presence of CI in MHD patients was 0.785 (95% CI: 0.704～0.866, P<0.001) and the optimal cut-off value was 0.15, at which the sensitivity and specificity were 74.5% and 76.0%, respectively.  Conclusion  Higher blood copper-zinc ratio is an independent risk factor for the development of CI in MHD patients.  Blood copper-zinc ratio is useful for the prediction of CI in MHD patients.

Key words: Maintenance hemodialysis, Copper-zinc ratio, Cognitive impairment