Table 7. Discriminatory ability of each prediction model for any type of incident fracture based on the C-index, Net Reclassification Improvement (NRI), and Integrated Discrimination Improvement (IDI).

Variables	C-index (95% CI)	P-value	NRI	P	IDI	P-value
Established risk factors	0.784 (0.699–0.869)	Reference		Reference		Reference
Established risk factors + serum Mg	0.789 (0.705–0.873)	0.49	0.174	0.16	0.001	0.31
Established risk factors + L2-L4 BMD	0.825 (0.750–0.899)	0.076	0.497	0.0028**	0.039	0.012*
Established risk factors + serum Mg + L2-L4 BMD	0.830 (0.759–0.901)	0.041*	0.600	0.00044**	0.041	0.010*

Established risk factors include age, BMI, HD duration, past incident fracture, use of phosphate binders, total hip DXA BMD and 1//3 radius DXA BMD as covariates with P<0.05 in the univariate analysis.