Table 1.

Descriptive Statistics of the 17 Unique Indices^*

	n	%
Time Frame for Mortality
6 month^20,21	1	5.9
1 year^22–26	5	29.4
15 month²⁷	1	5.9
2 year²⁸	1	5.9
3 year^29,30	2	11.7
4 year³¹	1	5.9
5 year^32–37	6	35.3
Country
United States^{20,21,25,26,28,30,31,34–37}	10	58.8
United Kingdom^22,23,33	3	17.6
Italy^24,27	2	11.8
Russia²⁹	1	5.9
South Korea³²	1	5.9
C-statistics
0.50 to 0.59 (poor)	0	0
0.60 to 0.69 (moderate)^29,30	2	11.7
0.70 to 0.79 (good)^{22,23,25,31–34,38}	8	47.1
0.80 to 0.89 (very good)^{20,21,24,26–28,36,37}	7	41.2
0.90 to 1.00 (excellent)	0	0
Calibration
Well calibrated	13	76.5
<10% Difference^{22,24,26–28,30,31,34,35,37}	10	58.8
Hosmer-Lemeshow P > .05^33,36	2	11.8
Cox calibration regression²⁵ (perfect calibration: α = 0, β = 1)	1	5.9
Poorly calibrated (>10% difference)³²	1	5.9
Calibration curve only^20,21	1	5.9
Not reported^23,29	2	11.8
Usability^†
Clinically usable^{22,26–28,30,31,33,34,36,37}	10	58.8
Not usable^{20,21,23–25,29,32,35}	7	41.2

↵* Han et al.²⁰ and Duarte et al.²¹ use the same index.
↵† Usability: usable if the mortality risk can be calculated using the instrument and interpreted without referring to the text of the article and not usable otherwise.