Risk stratification based on nomogram
Patients were categorized into three groups according to their total scores on the nomogram using X-tile software: the low-risk group (total score ≤ 140), the intermediate-risk group (140 < total score < 223), and the high-risk group (total score ≥ 223). The differences in survival among these risk categories were compared using Kaplan–Meier curves and log-rank tests.