TABLE VI.

Risk of All-Cause or TKA-Specific Readmission 30 Days After TKA Based on Hospital Annual Volume of TKAs (N = 377,705)

	30-Day Readmissions*
	CMS TKA-Specific† (N = 2,449; C-Statistic = 0.66)		Expanded TKA-Specific‡ (N = 6,784; C-Statistic = 0.66)		All-Cause§ (N = 22,076; C-Statistic = 0.69)
Hospital Annual Volume#	OR (95% CI)	P Value	OR (95% CI)	P Value	OR (95% CI)	P Value
≤89 vs. ≥645	1.32 (1.16, 1.51)	<0.001	1.43 (1.32, 1.56)	<0.001	1.26 (1.20, 1.32)	<0.001
90-235 vs. ≥645	1.09 (0.97, 1.22)	0.160	1.24 (1.15, 1.33)	<0.001	1.05 (1.01, 1.09)	0.021
236-644 vs. ≥645	0.95 (0.84, 1.08)	0.429	1.01 (0.93, 1.08)	0.896	0.74 (0.71, 0.78)	<0.001

^*Readmission categories are not mutually exclusive. †Readmissions due to any of 8 diagnoses designated by the CMS as TKA-specific complications (see Appendix).

^‡Readmissions due to a diagnosis on an expanded list of TKA-specific complications, including 22 additional TKA-specific complications selected by a group of experts (see Appendix).

^§Readmissions due to all causes, including 918 conditions not included in the CMS-defined or expanded list of TKA-specific complications (see Appendix).

^#Thresholds for hospital annual volume were determined using SSLR analysis as described in the Materials and Methods section.