Figure 5: Risk classification for prognosis in dialysis patients aged ≥80 years. Each patient was categorized according to the number of selected risk factors using Cox regression multivariate analysis to evaluate the predictive potential of risk criteria for prognosis. Each existing risk factor was scored as 1, and scores for all the other risk factors were summated. Patients were classified into three groups according to the number of risk factors: the lowrisk group (patients with no risk factor), the intermediaterisk group (1 risk factors), and the highrisk group (2 risk factors). 
