Table 7.

Model performance validation and calibration analysis

Validation Metric	Value	95% CI / P-value
Discrimination vs. Base Model
IDI	0.0035	(0.0018–0.0052), P < 0.001
Total NRI	0.0130	P = 0.331
Internal Validation & Calibration
Optimism-Corrected C-index	0.6465	(Bootstrap, n = 2000)
Calibration Slope	0.980	(Ideal = 1.0)

Notes: IDI, integrated discrimination improvement; NRI, net reclassification improvement; C-index, concordance index; CI, confidence interval. Bootstrap validation was performed with 2000 resamples to assess internal validity