Table 5:

Category-based net reclassification improvement of the cardiac-specific comorbidity index compared with the recalibrated Charlson–Deyo and Elixhauser comorbidity indexes for predicting all-cause death

	Probability category*
	Charlson–Deyo comorbidity index	Cardiac-specific comorbidity index
		No. of patients at low risk	No. of patients at high risk	Total no. of patients
Death	No. of patients at low risk	< 5	< 5	8
	No. of patients at high risk	13	109	122
	Total no. of patients	15	115	130
No death	No. of patients at low risk	5170	199	5369
	No. of patients at high risk	3637	1001	4638
	Total no. of patients	8807	1200	10 007
Net reclassification improvement (CSCI versus CDCI)
Event	(6–13)/130 = −0.054
Nonevent	(3637–199)/10 007 = 0.344
Overall	−0.054 + 0.344 = 0.290
	Probability category*
	Elixhauser comorbidity index	Cardiac-specific comorbidity index
		No. of patients at low risk	No. of patients at high risk	Total no. of patients
Death	No. of patients at low risk	< 5	21	25
	No. of patients at high risk	11	94	105
	Total no. of patients	15	115	130
No death	No. of patients at low risk	7243	415	7658
	No. of patients at high risk	1564	785	2349
	Total no. of patients	8807	1200	10 007
Net reclassification improvement (CSCI versus ECI)
Event	(21–11)/130 = 0.077
Nonevent	(1564–415)/10 007 = 0.115
Overall	0.077 + 0.115 = 0.192

Note: CDCI = Charlson–Deyo comorbidity index, CSCI = cardiac-specific comorbidity index, ECI = Elixhauser comorbidity index.

^*We used a cut-off of 0.01 to categorize a patient as being at low versus high risk based on the patient’s predicted probability of death.