Patient-Reported Quality of Life Before and After Total Knee Arthroplasty: A Multicenter Observational Study

Figures & data

Figure 1 Flow chart showing the study screening and enrolment process.

Abbreviations: KOA, knee osteoarthritis; TKA, total knee arthroplasty.

Table 1 Reliability of KOOS-PS and EQ-5D-5L Scores at Five Time Points from Before Surgery to 6 Months After Surgery

Variable	Before Surgery	7 Days After TKA	1 Month After TKA	3 Months After TKA	6 Months After TKA
KOOS-PS score
Cronbach’s alpha	0.85	0.83	0.81	0.81	0.80
EQ-5D-5L score
Cronbach’s alpha	0.77	0.78	0.72	0.79	0.79

Abbreviations: EQ-5D-5L, European Quality of Life Five Dimension Five Level; KOOS-PS, Knee Injury and Osteoarthritis Outcome Score; TKA, total knee arthroplasty.

Table 2 Patients’ Demographic and Clinical Characteristics (n=404)

Variable	Classification	n (%)
Location	Hospital A	116 (28.71)
	Hospital B	71 (17.57)
	Hospital C	197 (48.76)
	Hospital D	20 (4.95)
Sex	Male	91 (22.53)
	Female	313 (77.48)
Age, years	<60	90 (22.28)
	60–74	242 (59.90)
	>74	72 (17.82)
Marital status	Unmarried	8 (1.98)
	Married	396 (98.02)
Education	Elementary school or below	221 (55.11)
	Junior high school	91 (22.69)
	Junior college or high school	49 (12.22)
	College/bachelor or above	40 (9.98)
Smoker	No	378 (93.56)
	Yes	26 (6.44)
Alcohol consumption	No	385 (95.30)
	Yes	19 (4.70)
Monthly family income, CNY [USD]	<2000*	198 (49.75)
	2000–4000	106 (26.63)
	>4000	94 (23.62)
Medical insurance	No	32 (7.92)
	Yes	372 (92.08)
Duration of illness, years	<5	174 (43.07)
	6–15	174 (43.07)
	>15	56 (13.86)
Expected duration of recovery, months	<1	350 (86.63)
	≥1	54 (13.37)
Hospital stay, days	<5	27 (6.72)
	6–8	118 (29.35)
	9–11	119 (29.60)
	>11	138 (34.33)
Daily exercise, minutes	None	141 (34.90)
	<30	106 (26.24)
	≥30	157 (38.86)
Body mass index	<18.5	5 (1.24)
	18.5–24	110 (27.23)
	24–28	164 (40.59)
	>28	125 (30.94)

Notes: 100 CNY equals approximately 14.9 USD (April 2019 exchange rate). *100 CNY ¥ equals approximately 14.9 US $ (April, 2019 exchange rate).

Table 3 EQ-5D-5L and KOOS-PS Mean Scores at Five Time Points from Before Surgery to 6 Months After Surgery

Variable	Before TKA	7 Days After TKA	1 Month After TKA	3 Months After TKA	6 Months After TKA
KOOS-PS
Mean±SD	65.774±15.02	59.627±13.03	67.046±12.46	72.925±11.47	76.984±10.82
EQ-5D-5L
Mean±SD	0.686±0.23	0.625±0.26	0.768±0.21	0.858±0.17	0.895±0.14

Note: Data are shown as mean±SD.

Abbreviations: EQ-5D-5L, European Quality of Life Five Dimension Five Level; KOOS-PS, Knee Injury and Osteoarthritis Outcome Score; TKA, total knee arthroplasty; SD, standard deviation.

Figure 2 Average health-related quality of life trajectory based on the EQ-5D-5L score in a 2-class growth mixture model.

Abbreviations: EQ-5D-5L, European Quality of Life Five Dimension Five Level; TKA, total knee arthroplasty.

Table 4 Comparison of Sociodemographic Characteristics Between the Stable and Rising Groups

Variable	Classification	Rising Group (n=359)	Stable Group (n=45)	p-value
Location, n (%)	Hospital A	102 (87.93)	14 (12.07)	0.167
	Hospital B	66 (92.96)	5 (7.04)
	Hospital C	176 (89.34)	21 (10.66)
	Hospital D	15 (75)	5 (25)
Sex, n (%)	Male	82 (90.11)	9 (9.89)	0.667
	Female	277 (88.50)	36 (11.50)
Age, years, n (%)	<60	81 (90)	9 (10)	0.703
	60–74	216 (89.26)	26 (10.74)
	>74	62 (86.11)	10 (13.89)
Marital status, N (%)	Unmarried	37 (84.09)	7 (15.91)	0.287
	Married	322 (89.44)	38 (10.56)
Education, n (%)	Elementary school or below	189 (85.52)	32 (14.48)	0.118
	Junior high school	85 (93.41)	6 (6.59)
	Junior college or high school	45 (91.84)	4 (8.16)
	College/bachelor or above	38 (95)	2 (5)
Smoker	No	295 (93.65)	83 (93.26)	0.894
	Yes	20 (6.35)	6 (6.74)
Alcohol consumption	No	299 (94.92)	86 (96.63)	0.501
	Yes	16 (5.08)	3 (3.37)
Income, CNY, n (%)	<2000*	163 (82.32)	35 (17.68)	<0.001
	2000–4000	98 (92.45)	8 (7.55)
	>4000	93 (98.94)	1 (1.06)
Medical insurance, n (%)	No	331 (88.98)	41 (11.02)	0.799
	Yes	28 (87.5)	4 (12.5)
Duration of illness, years, n (%)	<5	151 (86.78)	23 (13.22)	0.134
	6–15	154 (88.51)	20 (11.49)
	>15	54 (96.43)	2 (3.57)
Expected duration of recovery, months, n (%)	<1	311 (88.86)	39 (11.14)	0.995
	≥1	48 (88.89)	6 (11.11)
TKA, n (%)	No	323 (88.49)	42 (11.51)	0.472
	Yes	36 (92.31)	3 (7.69)
OJD, n (%)	No	323 (88.493)	42 (11.51)	0.472
	Yes	36 (92.31)	3 (7.69)
Trauma, n (%)	No	290 (88.96)	36 (11.04)	0.901
	Yes	69 (88.46)	9 (11.54)
Hospital stay, days, n (%)	<5	25 (92.59)	2 (7.41)	0.844
	6–8	105 (88.98)	13 (11.02)
	9–11	107 (89.92)	12 (10.08)
	>11	120 (86.96)	18 (13.04)
Daily exercise, minutes, n (%)	None	118 (83.69)	23 (16.31)	0.040
	<30	99 (93.40)	7 (6.60)
	≥30	142 (90.45)	15 (9.55)
Body mass index, n (%)	<18.5	3 (60)	2 (40)	0.159
	18.5–24	100 (90.91)	10 (9.09)
	24–28	143 (87.20)	21 (12.81)
	>28	113 (90.4)	12 (9.6)
KOOS-PS_I		60.150 ±4.09	56.156 ±7.94	0.002
KOOS-PS_S		7.685 ±2.06	5.674 ±1.92	<0.001
VAS_C	Decreasing group	297 (94.29)	18 (5.71)	<0.001
	Stable group	62 (69.66)	27 (30.34)

Notes: Data are shown as mean±SD or n (%). KOOS-PS_I is the intercept term for KOOS-PS, and KOOS-PS_S is the slope term for KOOS-PS. VAS_C is the categorical latent variable of VAS for the decreasing group (n=315) and Stable group (n=89). *100 CNY equals approximately 14.9 USD (April 2019 exchange rate).

Abbreviations: EQ-5D-5L, European Quality of Life Five Dimension Five Level; KOOS-PS, Knee Injury and Osteoarthritis Outcome Score; OJD, Other Joint Diseases.

Table 5 Logistic Regression with EQ-5D-5L_C as the Dependent Variable

Variable	Univariable OR (95% CI)	p-value	Multivariable* OR (95% CI)	p-value
KOOS-PS_I, per SD	2.01 (1.506–2.754)	<0.001	2.26 (1.517–3.519)	<0.001
KOOS-PS_S, per SD	3.26 (2.201–5.014)	<0.001	2.60 (1.656–4.311)	<0.001
Income, CNY
<2000	Reference		Reference
2000–4000	2.63 (1.228–6.308)	0.019	6.19 (2.155–21.567)	0.002
>4000	19.97 (4.206–357.716)	0.003	19.73 (3.767–366.688)	0.005
Daily exercise, minutes
None	Reference		Reference
<30	2.76 (1.189–7.194)	0.025	2.95 (1.061–9.022)	0.045
≥30	1.85 (0.929–3.764)	0.084	1.62 (0.664–4.024)	0.292
VAS_C
Stable group	Reference		Reference
Decreasing group	7.19 (3.758–14.055)	<0.001	6.09 (2.715–14.074)	<0.001

Notes: EQ-5D-5L_C: the categorical latent variable of EQ-5D-5L for the rising group (n=359) and stable group (n=45). The stable group is the reference group. *Adjusted for KOOS-PS_ I, KOOS-PS _S, family monthly income, exercise, VAS_C.

Abbreviations: CI, confidence interval; EQ-5D-5L, European Quality of Life Five Dimension Five Level; KOOS-PS, Knee Injury and Osteoarthritis Outcome Score; OR, odds ratio; VAS, visual analogue scale.