Appendix 4.

Patient and Healthcare System Related Characteristics Based on the Propensity Scoring Matched Samples

Patient and Healthcare System Related Demographics (based on propensity matching)
	No SA diagnosis		SA Diagnosis
	N	%	N	%	STD (%)
Total	84,531	75	28,177	25
Average Age (Year) (SD)	63.63 (10.56)		63.70 (9.56)		0.63
Gender
Female	13,203	15.6	4,071	14.5	2.16
Male	71,328	84.4	24,106	85.6
Race
White	68,623	81.2	22,331	79.3	4.84
Black	5,834	6.9	2,250	8.00	4.13
Hispanic	1,321	1.6	498	1.8	1.60
Other	8,753	10.4	3,098	11.00	2.07
Average Deyo Index a (SD)	0.82 (1.04)		0.87 (1.05)		4.36
Deyo Index Category
0	45,444	53.8	14,452	51.3	4.95
1	16,042	19.00	5,659	20.1	2.79
2	16,588	19.6	5,708	20.3	1.59
≥ 3	6,457	7.6	2,358	8.4	2.69
Type of Procedure
THA	71,328	84.4	24,106	85.6	2.46
TKA	13,203	15.6	4,071	14.5
Type of Anesthesia
N	8,342	9.9	2,874	10.2	1.10
G	64,747	76.6	21,397	75.9	1.55
N+G	11,442	13.5	3,906	13.9	0.95
Year of Procedure
2006	11,886	14.1	4,064	14.4	1.04
2007	15,122	17.9	5,103	18.1	0.58
2008	17,690	20.9	5,913	21.00	0.14
2009	22,472	26.6	7,341	26.1	1.21
2010	17,361	20.5	5,756	20.4	0.27
Admission Type
Emergent	1,867	2.2	694	2.5	1.68
Urgent	3,095	3.7	1,175	4.2	2.62
Elective	79,321	93.8	26,253	93.2	2.70
Other	248	0.3	55	0.2	1.99
Indication
RA	2,151	2.5	829	2.9	2.43
OA	80,487	95.2	26,588	94.4	3.85
Other	1,893	2.2	760	2.7	2.95
Hospital Size (Beds)
< 299	25,619	30.3	8,610	30.6	0.54
300-499	34,874	41.3	11,602	41.2	0.16
≥ 500	24,038	28.4	7,965	28.3	0.38
Hospital Location
Rural	71,328	84.4	24,106	85.6	2.48
Urban	13,203	15.7	4,071	14.5
Hospital Teaching Status
Non-Teaching	71,328	84.4	24,106	85.6	1.25
Teaching	13,203	15.6	4,071	14.5

^aThe Deyo Index was validated for the outcomes of complications, mortality, blood transfusion, use of hospital resources, and other adverse events on a cohort of surgical patients ¹³.