Does ethnicity and education influence preoperative disability and expectations in patients undergoing total knee arthroplasty?

Table 1 Characteristics of the total patient population n (%)

	All patients
Baseline characteristics
BMI (mean ± SD)	29.7 ± 5
Age (mean ± SD)	66.8 ± 10
Gender
Male	308 (36.6)
Female	534 (63.4)
Smoking
Non-smoker	492 (58.6)
Former smoker	213 (25.4)
Active smoker	134 (16)
Duration of education
More than 12 yr	255 (30.8)
9-12 yr	371 (44.8)
0-9 yr	203 (24.5)
Ethnicity
Born in Denmark	764 (92.2)
Born outside Denmark	65 (7.8)
Preoperative level of function and symptoms
Walking aid outside the home:
None	597 (71.2)
One cane	133 (15.9)
Two canes	34 (4.1)
Wheeled walker	69 (8.2)
Do not leave the home	6 (0.7)
Oxford knee score (mean ± SD)	23.6 ± 8
Knee pain during activity1, median (range)	63 (0:100)
Quality of life1, median (range)	47 (0:100)
Level of symptoms1, median (range)	50 (0:100)
Preoperative expectations
Knee pain 1 yr after surgery1, median (range)	2 (0:100)
Quality of life 1 yr post-OP1, median (range)	94 (0:100)
Level of symptoms. 1 yr post-OP1, median (range)	3 (0:99)

¹Visual analogue scale 0-100. BMI: Body mass index.

Table 2 Significance of ethnicity n (%)

	Majority ethnicity	Minority ethnicity		P value (adjusted)
Baseline characteristics
BMI (mean ± SD)	29.7 ± 5	29.9 ± 4		0.702 (3.508)
Age (mean ± SD)	67.0 ± 10	64.0 ± 9		0.009 (0.045)
Gender
Male	294 (37.36)	11 (15.22)		< 0.001 (0.004)
Female	470 (62.64)	54 (84.78)
Smoking
Non-smoker	430 (56.3)	55 (84.6)		< 0.001 (< 0.001)
Former smoker	207 (27.1)	4 (6.5)
Active smoker	127 (16.6)	6 (9.2)
Duration of education
More than 12 yr	248 (32.5)	7 (10.8)		< 0.001 (< 0.001)
9-12 yr	369 (47.1)	11 (16.9)
0-9 yr	156 (20.4)	47 (72.3)
Preoperative level of function and symptoms
Walking aid outside the home:
None	556 (72.8)	34 (52.3)		0.005 (0.026)
One cane	111 (14.9)	20 (30.8)
Two canes	30 (3.9)	3 (4.6)
Wheeled walker	61 (8)	8 (12.3)
Do not leave the home	6 (0.8)	0 (0)
Oxford knee score (mean ± SD)	23.9 ± 7	18.6 ± 8		< 0.001 (< 0.001)
Knee pain during activity1, median (range)	61.0 (0:100)	76 (13:100)		< 0.001 (< 0.001)
Quality of life before surgery1, median (range)	47.0 (0:100)	38 (0:100)		0.388 (1.938)
Level of symptoms before surgery1, median (range)	50.0 (0:100)	61 (0:100)		0.276 (1.380)
Preoperative expectations
Expectations to knee pain caused by use of hip 1 yr after surgery1, median (range)	2.0 (0:100)	4 (0:99)		0.005 (0.016)
Expectations to quality of life 1 yr after surgery1, median (range)	94.0 (0:100)	92 (0:100)		0.296 (0.888)
Expectations to level of symptoms 1 yr after surgery1, median (range)	3.0 (0:99)	6 (0:99)		0.005 (0.016)
Postoperative level of function and symptoms:
Oxford knee score, median (range)	39.0 (3.0:48.0)	24.0 (10.0:47.0)		< 0.001 (0.002)
Knee pain during act1, median (range)	18.0 (0.0:100.0)	62.0 (5.0:90.0)		< 0.001 (< 0.001)
Quality of life1, median (range)	71.5 (0.0:100.0)	40.0 (0.0:95.0)		< 0.001 (0.001)
Level of symptoms1, median (range)	21.0 (0.0:100.0)	62.0 (10.0:90.0)		< 0.001 (0.001)
Difference in outcome parameters:
Difference in Pain1, median (range)	13.0 (90.0:100.0)		47.0 (37.0:90.0)	0.008 (0.0499)
Difference in Quality of life after surgery1, median (range)	15.0 (100.0:98.0)		44.0 (99.0:38.0)	0.013 (0.078)
Difference in level of symptoms1, median (range)	17 (56.0:100.0)		46.0 (36.0:88.0)	0.299 (1.796)

¹Visual analogue scale 0-100. BMI: Body mass index.

Table 3 Significance of duration of education n (%)

	Education 0-9 yr	Education 9-12 yr	Education > 12 yr	P value (adjusted)
Baseline characteristics
BMI, mean ± SD	28.7± 5	30.0 ± 6	30.5 ± 5	< 0.001 (0.007)
Age, mean ± SD	64.8 ± 10	67.8 ± 10	67.7 ± 11	< 0.001 (0.005)
Gender
Male	92 (36.1)	159 (42.9)	54 (26.6)	< 0.001 (0.003)
Female	163 (63.9)	212 (57.1)	149 (73.4)
Ethnicity
Majority ethnicity	248 (97.3)	360 (97)	156 (76.8)	< 0.001 (< 0.001)
Minority ethnicity	7 (2.7)	11 (3)	47 (23.2)
Smoking:
Non-smoker	155 (60.8)	207 (55.8)	123 (60.6)	0.003 (0.017)
Former smoker	74 (29)	100 (27)	37 (18.2)
Active smoker	26 (10.2)	64 (17.3)	43 (21.2)
Preoperative level of function and symptoms
Walking aid outside the home	198 (77.6)	273 (73.6)	119 (58.6)	0.005 (0.002)
None	35 (13.7)	55 (14.8)	41 (20.2)
One cane	11 (4.3)	12 (3.2)	10 (4.9)
Two canes	10 (3.9)	27 (7.3)	32 (15.8)
Wheeled walker housebound	1 (0.4)	4 (1.1)	1 (0.5)
Oxford knee score, mean ± SD	24.6 ± 8	23.8 ± 7	21.5 ± 8	< 0.001 (< 0.001)
Knee pain during activity1, median (range)	59 (0:99)	63 (0:100)	67 (6:100)	< 0.001 (0.002)
Quality of life before surgery1, median (range)	45 (0:100)	47 (0:100)	50 (0:100)	0.634 (3.170)
Level of symptoms before surgery1, median (range)	51 (0:100)	50 (0:100)	50 (0:100)	0.634 (3.171)
Preoperative expectations
Expectations to knee pain caused by use of hip 1 yr after surgery1, median (range)	4 (0:95)	2 (0:96)	2 (0:100)	0.003 (0.008)
Expectations to quality of life 1 yr after surgery1, median (range)	90 (0:100)	94 (0:100)	96 (0:100)	< 0.001 (0.002)
Expectations to level of symptoms 1 yr after surgery1, median (range)	4 (0:82)	2 (0:99)	2 (0:99)	< 0.001 (0.001)
Postoperative level of function and symptoms:
Oxford knee score, median (range)	40 (8.0:47.0)	37 (3.0:48.0)	37.5 (7.0:48.0)	0.240 (0.960)
Knee pain during activity, Post-OP1, median (range)	12 (0.0:90.0)	20 (0.0:100.0)	26 (0.0:97.0)	0.002 (0.006)
Quality of life after surgery1, median (range)	77.5 (13.0:98.0)	70 (0.0:100.0)	69 (0.0:100.0)	0.055 (0.219)
Level of symptoms after surgery1, median (range)	21 (0.0:94.0)	23 (0.0:100.0)	31 (0.0:95.0)	0.182 (0.728)
Difference in outcome parameters:
Difference in Pain1, median (range)	8 (-11.0:84.0)	15 (-90.0:100.0)	21 (-48.0:97.0)	0.012 (0.069)
Difference in Quality of life Post-OP1, median (range)	-7 (-67.0:95.0)	-20 (-100.0:98.0)	-18 (-99.0:98.0)	0.003 (0.017)
Difference in level of symptoms1, median (range)	15 (-14.0:89.0)	17 (-56.0:100.0)	18 (-41.0:95.0)	0.532 (3.193)

¹Visual analogue scale 0-100. BMI: Body mass index.