B2M and Cognitive impairment: The ROC curve analysis revealed that urinary β2M levels were better predictors of cognitive impairment in patients with CKD than urine NGAL and KIM-1 levels (AUC = 0.69 for β2M, 0.67 for NGAL, 0.54 for NGAL, and 0.62 for KIM-1, respectively).