highly significantp = 0.008
+ Vitamin D Tier (Full VDIBS): AUC 0.78 (95% CI 0.73–0.81) ○ Incremental benefit: ΔAUC = +0.05 (95% CI +0.02 to +0.08, p = 0.004); ○ Likelihood ratio test: χ 2 (1 df) = 8.4, p = 0.004 (highly significant); ○ Net Reclassification Improvement: NRI = 0.12 ( p = 0.008); ○ Integrated Discrimination Improvement: IDI = 4.2% ( p = 0.012).