Table 3. Discrimination parameters of four models for predicting the composite outcome.

		Harrell ’s C	95%CI		NRI	p value	IDI	p value
Model 1	Established risk factors	0.700	(0.656, 0.744)	Model 1	ref.	ref.	ref.	ref.
Model 2	Model 1 + ABI	0.703	(0.658, 0.749)	Model 2 vs. Model 1	0.275	0.028	0.012	0.073
Model 3	Model 1 + SPP	0.721	(0.677, 0.764)	Model 3 vs. Model 1	0.330	0.008	0.045	＜0.001
Model 4	Model 1 + ABI + SPP	0.721	(0.677, 0.765)	Model 4 vs. Model 2	0.359	0.004	0.033	0.003
				Model 4 vs. Model 3	0.109	0.382	0.001	0.712

We established risk prediction models for the composite event of death and AVEs. Model 1 includes the eight risk factors identified as in Table 2. In Models 2--4, the factors of SPP and/or ABI tertiles are added to Model 1.

Harrell ’s C, Harrell ’s C-statistic; NRI, net reclassification improvement; IDI, integrated discrimination improvement; CI, confidence interval; ref., reference; ABI, ankle-brachial index; SPP, skin perfusion pressure; AVEs, atherosclerotic vascular events.