Table 2.

Global measures of model fit, discrimination, and calibration statistics

Model evaluation measures	Base	CCI model	PRI model
Global measures
LR χ2	10,556	14,623	14,834
P-value*	<0.01	<0.01	<0.01
BIC	32,269	28,213	28,003
R2 (%)	24.8%	34.3%	34.8%
Brier (%)	3.9%	3.5%	3.5%
Discrimination
C-index (%)	86.9%	91.3%	91.5%
NRI (%)	–	74.5%	84.0%
IDI (%)	–	9.9%	10.7%
$\mathrm{\Delta }\widehat{\mathrm{p}}$†	–	2.6%	2.8%

Notes: Models include the base model with sex and age, the model including sex, age, and Charlson Comorbidity Index (CCI), and the model including sex, age, and the Patient Register Index (PRI), using an internal tenfold cross-validation procedure.

^*P-value for LR test between the base model and a model including CCI or PRI;

^† $\mathrm{\Delta }\widehat{\mathrm{P}}=\frac{1}{\mathrm{N}}{\displaystyle \sum _{\mathrm{i}=1}^{\mathrm{N}}\left|{\widehat{\mathrm{P}}}_{\text{age},\text{sex},\mathrm{i}}-{\widehat{\mathrm{P}}}_{\text{age},\text{sex},\text{comorbidity},\mathrm{i}}\right|.}$

Abbreviations: LR, likelihood ratio; BIC, Bayesian information criterion; NRI, net reclassification improvement; IDI, integrated discrimination improvement.