Table 3.

Patient, surgeon, implant, and hospital characteristics for the Reflection cohort, 2001–2011

Variables		Bearing surface
		All		Conventional polyethylene		HXLPE
		Number	Percent	Number	Percent	Number	Percent
	All	5202		753	15	4449	86
Sex	Male	1899	37	273	36	1626	37
	Female	3302	64	479	64	2823	64
	Missing	1	0.1	1	0.1	0	0
ASA category	1 or 2	2937	57	376	50	2561	58
	≥ 3	2188	42	358	48	1830	41
	Unknown	77	2	19	3	58	1
BMI category (kg/m2)	< 30	3161	61	455	60	2706	61
	≥ 30 and < 35	1162	22	144	19	1018	23
	≥ 35	734	14	95	13	639	14
	Unknown	145	3	59	8	86	2
Race	Asian/Pacific Islander	200	4	21	3	179	4
	Black	392	8	34	5	358	8
	Native American	9	0.2	3	0.4	6	0.1
	White	3721	72	501	67	3220	72
	Hispanic	449	9	73	10	376	9
	Other	71	1	9	1	62	1
	Unknown	360	7	112	15	248	6
Diabetes	Yes	1307	25	195	26	1112	25
Surgeon fellowship	Yes	1948	37	334	44	1614	36
	Missing	0	0.1	0	1	0	0
Surgeon average annual volume category	< 10	336	7	41	5	295	7
	10 to < 50	3569	69	614	82	2955	66
	≥ 50	1297	25	98	13	1199	27
	Missing	0	0.2	0	0.1	0	0
Site average annual volume category	< 100	756	15	54	7	702	16
	100 to < 200	3592	69	570	76	3022	68
	≥ 200	854	16	129	17	725	16
	Missing	0	0.1	0	0.4	0	0
Fixation	Uncemented	3315	64	256	34	3059	69
	Hybrid	1549	30	446	59	1103	25
	Cemented	56	1	6	1	50	1
	Missing	282	5	45	6	237	5
Head size	≤ 28 mm			685	91	1719	39
	32 mm			68	9	2065	46
	36 mm			0	0.1	665	15
	> 36 mm			0	0.4	0	0

	Mean	SD	Mean	SD	Mean	SD
Membership termination
Yes	534	10	128	17	406	9
Operative time (minutes)	90	31	94	31	90	31
Age (years)	72	9	73	8	71	9
BMI (kg/m2)	29	6	29	6	29	6
Days of followup	1899	869	2412	1029	1812	808

HXLPE = highly crosslinked polyethylene; ASA = American Society of Anesthesiologists; BMI = body mass index.