BDNF and chronic kidney disease: Figure 3 shows the receiver operating characteristic curves to differentiate CKD using the BDNF alone model, the VCAM-1 alone model, and the BDNF + VCAM-1 model. The C index was 0.645 (95% CI: 0.531–0.762), 0.746 (95% CI: 0.643–0.844), and 0.756 (95% CI: 0.657–0.853); respectively. The C index is significantly higher in the BDNF + VCAM-1 model than in the BDNF alone model (P < 0.001), but not significantly different from that in the VCAM-1 model (P = 0.263).