Table 4. Comparison of characteristics for rheumatoid arthritis and osteoarthritis patients by calendar year.

		Year
		2009				2010				2011
	OA		RA		OA		RA		OA		RA
		N	(%)	N	(%)	N	(%)	N	(%)	N	(%)	N	(%)
	All	10233	98.5	156	1.5	11571	98.5	180	1.5	12011	98.7	160	1.3
TJA	THA	3561	34.8	47	30.1	3831	33.1	65	36.1	4056	33.8	55	34.4
	TKA	6672	65.2	109	69.9	7740	66.9	115	63.9	7955	66.2	105	65.6
Age category, years	<65	4067	39.7	84	53.9	4435	38.3	104	57.8	4735	39.4	91	56.9
	>=65	6166	60.3	72	46.2	7136	61.7	76	42.2	7276	60.6	69	43.1
Female gender	Female	6274	61.3	110	70.5	7084	61.2	135	75.0	7336	61.1	118	73.8
Race1	White	7260	71.0	75	48.1	7997	69.1	78	43.3	8285	69.0	70	43.8
	Hispanic	1266	12.4	39	25.0	1476	12.8	54	30.0	1713	14.3	53	33.1
	Black	894	8.7	22	14.1	1090	9.4	22	12.2	1065	8.9	22	13.8
	Asian	585	5.7	15	9.6	784	6.8	25	13.9	745	6.2	14	8.8
	Other/Multi	211	2.1	4	2.6	208	1.8	1	0.6	190	1.6	1	0.6
BMI category (kg/m2)1	<30	5109	49.9	105	67.3	5818	50.3	97	53.9	6144	51.2	90	56.3
	30-34	2909	28.4	23	14.7	3245	28.0	50	27.8	3383	28.2	38	23.8
	≥35	2208	21.6	28	18.0	2507	21.7	33	18.3	2480	20.7	32	20.0
ASA category	1&2	6023	58.9	85	54.5	6825	59.0	82	45.6	7067	58.8	81	50.6
	>=3	4145	40.5	70	44.9	4655	40.2	97	53.9	4874	40.6	79	49.4
Diabetes		2534	24.8	31	19.9	2784	24.1	36	20.0	2809	23.4	28	17.5
Deficiency Anemia		1358	13.3	34	21.8	1366	11.8	47	26.1	1391	11.6	42	26.3
LOS	<=2 day	3035	29.7	39	25.0	4397	38.0	56	31.1	5456	45.4	71	44.4
	3 day	5209	50.9	86	55.1	5339	46.1	89	49.4	5000	41.6	72	45.0
	4 day	1276	12.5	19	12.2	1162	10.0	23	12.8	1019	8.5	11	6.9
	>=5 day	673	6.6	11	7.1	655	5.7	11	6.1	524	4.4	6	3.8
Surgeon TJA Fellowship	Fellowship	3907	38.2	78	50.0	4609	39.8	76	42.2	4846	40.4	77	48.1
Hospital yearly volume, cases/yr	<100	515	5.0	8	5.1	583	5.0	6	3.3	709	5.9	9	5.6
	100-199	3928	38.4	53	34.0	4597	39.7	75	41.7	4872	40.6	63	39.4
	>=200	5790	56.6	95	60.9	6391	55.2	99	55.0	6430	53.5	88	55.0
Surgeon yearly volume, cases/yr	<20	916	9.0	14	9.0	1061	9.2	16	8.9	1137	9.5	15	9.4
	20-49	4372	42.7	61	39.1	4810	41.6	86	47.8	5105	42.5	73	45.6
	>=50	4945	48.3	81	51.9	5700	49.3	78	43.3	5769	48.0	72	45.0
Discharge disposition	Home	8074	78.9	121	77.6	9017	77.9	144	80.0	9539	79.4	126	78.8
	Other	2125	20.8	34	21.8	2535	21.9	36	20.0	2455	20.4	34	21.3
Intra-operative complications	Surgical	488	4.8	7	4.5	507	4.4	10	5.6	481	4.0	4	2.5
	Non Surgical	85	0.8	3	1.9	100	0.9	1	0.6	92	0.8	0	0.0

¹Missing data: race (n=47, <0.1%), BMI (n=12, <0.1%), ASA (n=228, 0.7%), discharge disposition (n=71, 0.2%), LOS (n=72, 0.2%).

OA=Osteoarthritis. RA=Rheumatoid Arthritis. TJA=Total Joint Arthroplasty. THA=Total Hip Arthroplasty. TKA= Total Knee Arthroplasty. BMI=Body Mass Index. ASA=American Society of Anesthesiologists. LOS=Length of Stay.