Total knee arthroplasty status and patient-reported, knee-related quality of life over a 4-year follow-up period: data from the osteoarthritis initiative

Figures & data

Figure 1 Flow of the study sample.

Notes: *The Osteoarthritis Initiative Study has made large, heterogeneous datasets available for public use.^{26 #}Participants with symptomatic tibiofemoral knee OA at baseline. ^‡Participants with no symptomatic tibiofemoral OA in either knee at baseline. ^§Participants with no pain, aching, or stiffness in either knee in the past year; no radiographic findings of OA; and no eligibility risk factors. ^¶Participants considering, for either knee, knee replacement surgery in the next 3 years. ^±Participants, for either knee, had undergone TKA at baseline, confirmed by baseline X-ray.
Abbreviations: TKA, total knee arthroplasty; OA, osteoarthritis; OAI, Osteoarthritis Initiative.

Table 1 Baseline descriptive characteristics of the sample, n=4,674

Variables	No knee OA N=3,711 (79%)	Non-TKA N=902 (19%)	Pre-TKA N=36 (1.5%)	Post-TKA N=25 (0.5%)	P-value
Age in years	61.2±9.1	61.4±9.2	60.0±9.7	69.8±7.1	<0.0001
Gender					0.0385
Male	1,505 (41)	411 (46)	17 (47)	12 (48)
Female	2,206 (59)	491 (54)	19 (53)	13 (52)
Race					<0.0001
White or Caucasians	2,959 (80)	676 (75)	18 (50)	24 (96)
African American/Asian/non-whites	752 (20)	226 (25)	18 (50)	1 (4)
Education					0.0303
High school or less	588 (16)	166 (18)	11 (31)	5 (20)
More than high school	3,123 (84)	736 (82)	25 (69)	20 (80)
Marital status					0.0115
Married	2,444 (66)	305 (34)	20 (56)	4 (16)
Unmarried/divorced/widow	1,267 (34)	597 (66)	16 (44)	21 (84)
Income per year in US dollars					<0.0001
<50,000	1,358 (37)	362 (40)	27 (75)	11 (44)
>50,000	2,353 (63)	540 (60)	9 (25)	14 (56)
Health care coverage					0.0189
Yes	3,553 (96)	852 (94)	31 (86)	24 (96)
No	158 (4)	50 (6)	5 (14)	1 (4)
Charlson comorbidity index					<0.0001
0	2,800 (84)	621 (79)	16 (59)	16 (84)
>1	538 (16)	167 (21)	11 (41)	3 (16)
Depressive symptoms					<0.0001
CESD <16	3,366 (91)	786 (87)	24 (67)	22 (88)
CESD >16	345 (9)	116 (13)	12 (33)	3 (12)
BMI, kg/m^2	28.4±4.8	29.8±4.8	31.5±5.9	29.9±4.5	<0.0001
PASE	160.7±82.4	161.0±83.3	134.9±89.5	121.1±70.4	<0.0001
KOOS-QoL	69.7±28.3	52.3±19.7	39.0±22.9	66.0±26.6	<0.0001

Note: Values are presented as mean ± SD or n (%).

Abbreviations: BMI, body mass index; CESD, Center for Epidemiologic Studies Depression Scale; KOOS-QoL, Knee Injury and Osteoarthritis Outcome Score-Quality of Life subscale; OA, osteoarthritis; PASE, Physical Activity Scale for Elderly; SD, standard deviation; TKA, total knee arthroplasty.

Table 2 General linear mixed model estimates for the KOOS-QoL subscale score over a 4-year period by TKA or knee OA status at baseline, n=4,674

Predictor variables	Model 1 estimate (SE)	P-value	Model 2 estimate (SE)	P-value
Intercept	51.22 (2.83)	<0.0001	61.74 (2.95)	<0.0001
Time	−0.38 (0.03)	<0.0001	−0.38 (0.03)	<0.0001
Main effect
No knee OA	Reference		Reference
Non-TKA	−14.28 (0.74)	<0.0001	−13.97 (0.73)	<0.0001
Pre-TKA	−21.50 (3.41)	<0.0001	−21.34 (3.57)	<0.0001
Post-TKA	−9.42 (3.91)	0.0161	−9.68 (3.94)	0.0143
Interaction with time
No knee OA × Time	Reference		Reference
Non-TKA × Time	−0.15 (0.07)	0.0302	−0.16 (0.07)	0.0226
Pre-TKA × Time	−0.50 (0.31)	0.1107	−0.25 (0.34)	0.4561
Post-TKA × Time	0.16 (0.36)	0.6626	0.15 (0.37)	0.6821

Notes: Model 1: Adjusted for time, age, sex, race, marital status, education, annual income, and health care coverage. Model 2: Adjusted for depressive symptoms, PASE, BMI, comorbidities along with variables in Model 1.

Abbreviations: BMI, body mass index; KOOS-QoL, Knee Injury and Osteoarthritis Outcome Score-Quality of Life subscale; OA, osteoarthritis; PASE, Physical Activity Scale for Elderly; SE, standard error; TKA, total knee arthroplasty.

Figure 2 Means for the KOOS-QoL subscale score over a 4-year period, by TKA or knee OA status at baseline, n=4,674.

Notes: (A) Adjusted for sociodemographic variables. (B) Adjusted for sociodemographic and health variables.
Abbreviations: CG,; KOOS-QoL, Knee Injury and Osteoarthritis Outcome Score-Quality of Life subscale; OA, osteoarthritis; TKA, total knee arthroplasty.