Association of Weight Change and Physical Activity with Knee Pain and Health-Related Quality of Life in East Asian Women Aged 50 Years and Older with Knee Osteoarthritis: A Population-Based Study

Article information

Kosin Med J. 2021;36(2):125-135

Publication date (electronic) : 2021 December 31

doi : https://doi.org/10.7180/kmj.2021.36.2.125

Chong Bum Chang ¹, Young Choi ², Seung Baik Kang ³, Chin Youb Chung ¹, Moon Seok Park ¹, Kyoung Min Lee ¹

¹Department of Orthopaedic Surgery, Seoul National University Bundang Hospital, Gyeonggi-do, Republic of Korea

²Department of Orthopaedic Surgery, Kosin University Gospel Hospital, Busan, Republic of Korea

³Department of Orthopaedic Surgery, SMG-SNU Boramae Medical Center, Seoul National University College of Medicine, Seoul, Republic of Korea

Corresponding Author: Kyoung Min Lee, Department of Orthopaedic Surgery, Seoul National University Bundang Hospital, 82, Gumi-ro, 173 beon-gil, Bundang-gu, Seongnam-si, Gyeonggi-do 13620, Republic of Korea, Tel: +82-31-787-7203, Fax: +82-31-787-4056, E-mail: oasis100@empal.com

Received 2021 October 01; Revised 2021 November 26; Accepted 2021 December 04.

Abstract

Objectives

This study aimed to investigate the association of self-reported weight change and physical activity with the level of knee pain and health-related quality of life in East Asian women with knee osteoarthritis using population-based data.

Methods

A total of 564 women (mean age, 68.2 years, standard deviation, 8.9 years) aged 50 years or older with knee osteoarthritis (Kellgren-Lawrence (K-L) grade ≥ 2) were included in the data analyses from the fifth Korea National Health and Nutrition Examination Survey. Data regarding the radiographic grade, self-reported weight change during the past year, physical activity, level of knee pain, and health-related quality of life (EuroQOL five-dimension (EQ-5D) index) were collected. Multiple regression analysis was performed to identify factors significantly associated with the level of knee pain and health-related quality of life in subgroups according to the body mass index (BMI) range (≤ 22.5, between 22.6 and 27.5, and > 27.5 kg/m²).

Results

In the whole group, the level of knee pain was significantly associated with K-L grade (P < 0.001), and EQ-5D was negatively associated with age (P < 0.001), the level of knee pain (P < 0.001), and weekly hours of vigorous-intensity activity (P = 0.026). In the subgroup analysis, weight gain showed significant association with the level of knee pain only in women with 22.5 kg/m² < BMI ≤ 27.5 kg/m² (P = 0.006). Weight gain showed significant association with EQ-5D in women with BMI ≤ 22.5 kg/m² (P = 0.047) whereas weekly hours of moderate-intensity activity was negatively associated with EQ-5D in women with BMI > 27.5 kg/m².

Conclusions

The association of weight change and physical activity with knee pain and health-related quality of life might be different according to BMI ranges. Well-designed interventions to improve both knee pain and health-related quality of life need to be investigated in future studies that would strictly control physical activity, diet, and weight changes.

Keywords: Health-related quality of life; Knee pain; Osteoarthritis; Physical activity Weight change

Knee osteoarthritis is one of the most prevalent orthopedic disorders that adversely affects the patients’ health-related quality of life, especially in the elderly population.1,2 Knee pain is an important clinical parameter when determining the necessity of surgical treatment and the treatment outcomes.3,4 Therefore, physicians need to understand the factors affecting the level of knee pain and quality of life in patients with knee osteoarthritis.

Previous studies showed that various factors could affect arthritic knee pain, including the radiographic grade of osteoarthritis, presence of spine or hip diseases, obesity, and psychiatric disorders. 5 Obesity is known to affect arthritic pain by increasing mechanical load on the joint as well as by increasing inflammatory cytokine through the arachidonic pathway, which eventually could lead to development and progression of knee osteoarthritis. 6–8 Therefore, obesity has been acknowledged as an important modifiable factor that affects the prognosis of knee osteoarthritis.6,9–14

A study reported that weight loss and moderate activity were effective in improving function and pain in obese patients with knee osteoarthritis.15 However, there is little evidence that weight loss is an effective treatment in nonobese patients, especially in the Asian population. Theoretically, body weight and physical activity can exert complicated effects on the mechanical load on joints, and their relationship could be a confounding factor when analyzing this effect because although physical activity helps reduce body weight, it could also increase joint loading.

Therefore, the authors hypothesized that categorization of body mass index (BMI) and physical activity would provide more clinically relevant analysis. This study aimed to investigate the association of self-reported weight change and physical activity with knee pain and health-related quality of life in Asian women with knee osteoarthritis (Kellgren-Lawrence grade ≥ 2) using population-based data.

MATERIALS AND METHODS

Subjects

The Korean National Health and Nutrition Examination Survey (KNHNES) is a national population-based study conducted by the Korean Centers for Disease Control and Prevention annually from 1998. The subjects are noninstitutionalized civilians who were randomly selected through stratified, multistage probability samples, which were based on age, sex, and residence area. This study includes questionnaires regarding health behavior and nutrition intake and health examinations such as body weight, height, blood pressure measurements, and blood tests. Specific health examinations are included according to the demand of national healthcare policies. Knee osteoarthritis examination and survey were performed in 2011.

A total of 10,589 population-based subjects were invited to participate in the 2011 survey, and 8518 agreed to participate, with a response rate of 80.4%. Of these, 1956 women aged 50 years and older were selected from the parent study. Knee osteoarthritis was defined radiographically as Kellgren-Lawrence grade ≥ 2,16,17 which was evaluated by two skeletal radiologists. A total of 830 women with knee osteoarthritis were selected, and exclusion criteria were use of osteoarthritis medication,18,19 presence of malignancies, and incomplete dataset. Finally, 564 women with knee osteoarthritis were analyzed after implementing the inclusion and exclusion criteria (Fig. 1).

Fig. 1

Flow diagram of the inclusion and exclusion criteria for the Korea National Health and Nutrition Examination Survey (KNHNES). A total of 564 women aged 50 years or older were included.

Written informed consent was obtained by the Korean Centers for Disease Control and Prevention from all participants. Approval from the ethical committee was exempted by the institutional review board at our hospital because this study utilized a publicly available database and did not have any potential violation of patient rights.

Data collection from the fifth KNHNES database

Demographic data including age, sex, body mass index (BMI), self-reported weight change in the past year (gain > 10 kg, gain of 6–10 kg, gain of 3–6 kg, gain < 3 kg, no change, loss < 3 kg, loss of 3–6 kg, loss of 6–10 kg, and loss > 10 kg) was collected. The parameters of height and weight were measured using standardized instruments, and BMI was calculated using the height and weight measurements. The percentage of weight change was calculated by dividing the weight change with body weight. Presence of malignant diseases and use of osteoarthritis medication were recorded using a health information questionnaire. The short form of the International Physical Activity Questionnaire20 was used to evaluate the subjects’ activity level, and weekly hours of vigorous-intensity, moderate-intensity, and walking activities were recorded.

Health-related quality of life was measured using the EuroQOL five-dimension (EQ-5D) index. The system comprises five dimensions including mobility, self-care, usual activities, pain/discomfort, and anxiety/depression.21,22

The knee osteoarthritis survey included severity of knee pain and radiographic examination. The severity of knee pain was evaluated using a 10-point numerical rating scale (NRS) (0 = no pain, 10 = severe pain). Knee X-rays were taken bilaterally with the subjects’ weight-bearing using an SD 3000 Synchro Stand (Accele Ray, SYFM Co., Seoul, South Korea), and the radiographic images were digitally stored. Severity of radiographic knee osteoarthritis was evaluated using the Kellgren-Lawrence grading system16,17 (grade 0, no features of osteoarthritis; grade 1, small osteophytes of uncertain significance; grade 2, definite osteophytes without impairment of joint space; grade 3, definite osteophytes with moderate joint space reduction; grade 4, definite osteophytes with substantial joint space narrowing and subchondral bone sclerosis). Presence of knee osteoarthritis was defined as Kellgren-Lawrence grades 2, 3, and 4.16,17 Radiographic evaluation was performed by two radiologists, and the agreement between the two was 85.2% for 81 randomly selected radiographic images with an intraclass correlation coefficient of 0.767 (95% confidence interval, 0.659 to 0.844). If a disagreement in radiographic findings between the two radiologists occurred, the higher grade was adopted.

Data analysis and statistics

Women with knee osteoarthritis were categorized into three groups according to BMI measurements considering the number of women in each group: those with BMI < 23.0 kg/m² (underweight and normal weight for Asian population), those with 23.0 kg/m² < BMI ≤ 27.5 kg/m² (overweight), and those with BMI > 27.5 kg/m² (obesity).25 Descriptive statistics included mean and standard deviation (SD) for continuous variables and proportion for categorical variables. Normal distribution of the data was tested using the Kolmogorov-Smirnov test. Means and frequency were compared using analysis of variance (ANOVA) test and chi-square test among the three groups, respectively. Correlation between the variables was analyzed using Pearson’s correlation coefficient or Spearman’s correlation coefficient according to data normality.

Multiple regression analysis was performed to identify the variables that significantly contributed to the level of knee pain (NRS) and health-related quality of life (EQ-5D), which were dependent variables. Candidate independent variables were selected and included in the regression model as enter mode when the variable showed P < 0.1 in the correlation tests. All statistical analyses were performed using SPSS version 20.0 (IBM Corp., Armonk, NY, USA), with statistical significance set at P < 0.05.

RESULTS

The characteristics of the patients included in the analysis are given in Table 1.

Table 1

Data summary

In all subjects, the severity of radiographic osteoarthritis (Kellgren-Lawrence grade) (P < 0.001) was the significant factor associated with the level of knee pain, whereas age (P < 0.001), level of knee pain (P < 0.001), and weekly hours of vigorous-intensity activity (P = 0.026) were the significant factors negatively associated with EQ-5D (Table 2). In the subgroup of women with BMI < 23.0 kg/m², Kellgren-Lawrence grade (P < 0.001) was the significant factor associated with the level of knee pain, and age (P < 0.001), level of knee pain (P < 0.001), and percentage change of weight during the past year (P = 0.032) were significantly associated with EQ-5D (Table 3). In the subgroup of women with 23.0 kg/m² ≤ BMI ≤ 27.5 kg/m², the Kellgren-Lawrence grade (P < 0.001) and percentage change of weight during the past year (P = 0.007) were found to be significant factors associated with the level of knee pain. Age (P = 0.006), level of knee pain (P < 0.001) and weekly hours of walking (P = 0.018) were the factors significantly associated with EQ-5D while weekly hours of vigorous-intensity activity (P = 0.005) was negatively associated with EQ-5D (Table 4). In the subgroup of women with BMI > 27.5 kg/m², age (P = 0.031) was the only significant factor associated with the level of knee pain, and age (P = 0.028), BMI (P = 0.024) and level of knee pain (P = 0.002) were the factors significantly associated with EQ-5D. Weekly hours of moderate-intensity activity (P = 0.006) was negatively associated with EQ-5D (Table 5).

Table 2

Multiple regression analysis in all subjects with knee osteoarthritis aged 50 years and older

Table 3

Multiple regression analysis in the subgroup of women with BMI<23.0 kg/m² aged 50 years and older with knee osteoarthritis

Table 4

Multiple regression analysis in the subgroup of women with 23.0 kg/m² ≤ BMI ≤ 27.5 kg/m² aged 50 years and older with knee osteoarthritis

Table 5

Multiple regression analysis in the subgroup of women with BMI > 27.5 kg/m² aged 50 years and older with knee osteoarthritis

For the correlation between activity and weight change, weekly hours of walking was the only factor that was significantly correlated with percentage change of weight during the past year (r = 0.215, P = 0.032) in the subgroup of women with BMI > 27.5 kg/m². There was no significant correlation between activity and weight change in the other subgroups.

DISCUSSION

This study investigated the factors associated with level of knee pain and health-related quality of life (EQ-5D), focusing on self-reported weight change and activity in community-based women aged 50 years and older with knee osteoarthritis. Important confounding factors were excluded from the data, such as presence of malignancy and osteoarthritis medication. We analyzed the data as subgroups stratified according to BMI classification for Asian population.23 Weight change and activity showed different association with level knee pain and health-related quality of life according to BMI subgroups.

In our whole cohort, BMI showed no significant correlation with knee pain or health-related quality of life. This is contrary to clinical consensus and previous study results that obesity has an important factor in the development and progression of osteoarthritis in terms of mechanical loading and biochemical pathway affecting inflammatory processes related with lipid metabolism. 6,14,24,25 The authors considered that BMI is a critical factor in pain and health-related quality of life and stratified the whole cohort according to BMI, specifically designed for Asian population. 23

In our study, contrary to previous studies,24,25 weight change during a year did not show significant correlation with the level of knee pain for the whole group of women aged 50 years and older with knee osteoarthritis. The association of weight change with knee pain showed differences according to BMI ranges. Weight reduction was significantly associated with lower level of knee pain in women with BMI range of overweight (23.0 kg/m² ≤ BMI ≤ 27.5 kg/m²). This result does not concur with previous studies that have shown that weight loss improved physical function and pain in overweight females with knee osteoarthritis.24, 25 This difference may have been due to differing exclusion criteria (malignancies and osteoarthritis medication), differing ethnicities, or the effect of combined intervention such as exercise and diet. Furthermore, weight loss alone might not decrease knee pain without appropriate exercise or concomitant intervention in obese patients with knee osteoarthritis. An interesting finding is that weight gain was positively associated with health-related quality of life (EQ-5D) in subgroup of women with a lower BMI (Table 3).

The amount of activity did not show any relationship with the level of knee pain in this community-based observational study, but it showed significant relationship with health-related quality of life. In the subgroup of women with 23.0 kg/m² ≤ BMI ≤ 27.5 kg/m², EQ-5D showed significant positive association with weekly hours of walking and negative association with that of vigorous-intensity activity. In the subgroup of women with BMI > 27.5 kg/m², weekly hours of moderate-intensity activity showed significant negative association with EQ-5D. Therefore, vigorous-intensity activity in overweight women and moderate-intensity activity in obese women might adversely affect the health-related quality of life in knee osteoarthritis. Further investigation is required to reveal the causal relationship between activity and quality of life controlling other important factors, especially diet intake.26–28

The amount of weight change and physical activity could be associated with the level of knee pain and health-related quality of life separately according to BMI ranges. Our study results suggested that weight reduction via walking exercise could reduce knee pain and improve health-related quality of life in the subgroup of Asian overweight women with knee osteoarthritis. However, the specific type of physical activity could impede the patients’ health-related quality of life depending on the BMI ranges. Therefore, more sophisticated intervention might be required regarding physical activity and weight loss according to ethnicity and BMI ranges in women with knee osteoarthritis. Future studies with strictly designed diet and physical activity are required to elucidate the relationships among weight loss, knee pain, and health-related quality of life.

There are some limitations to this study. First, this study was essentially a cross-sectional study depending on a health-related questionnaire and specific examination. Therefore, causal relationships between independent and dependent variables are not certain. A further, longitudinal study with the relevant hypothesis is required to verify the causality of the variables. Second, we excluded confounding factors such as presence of malignancy and osteoarthritis medication because these variables could significantly affect the level of knee pain. However, this exclusion might not reflect the usual clinical situation, although the study setting could evaluate the factors affecting knee pain more precisely in a community-based population without any medical intervention for knee osteoarthritis. Third, self-reported weight change over the past year was used in our study, which is yet to be validated. 29,30 This may have caused unknown bias.

The effect of weight change on knee pain could be different according to BMI ranges. Walking activity could improve the quality of life and a weight reduction could decrease knee pain in overweight Asian women with knee osteoarthritis. However, a longitudinal research is required to reveal the causal relationship among the factors, strictly controlling diet and physical activity.

ACKNOWLEDGEMENTS

This work was supported by clinical research grant from Seoul National University Hospital.

References

1. Bindawas SM, Vennu V, Auais M. Health-related quality of life in older adults with bilateral knee pain and back pain: data from the Osteoarthritis Initiative. Rheumatol Int 2015;35:2095–101.

2. Kiadaliri AA, Lamm CJ, de Verdier MG, Engstrom G, Turkiewicz A, Lohmander LS, et al. Association of knee pain and different definitions of knee osteoarthritis with health-related quality of life: a population-based cohort study in southern. Sweden Health Qual Life Outcomes 2016;14:121.

3. Bartley EJ, King CD, Sibille KT, Cruz-Almeida Y, Riley JL 3rd, Glover TL, et al. Enhanced Pain Sensitivity Among Individuals With Symptomatic Knee Osteoarthritis: Potential Sex Differences in Central Sensitization. Arthritis Care Res (Hoboken) 2016;68:472–80.

4. Dieppe PA, Lohmander LS. Pathogenesis and management of pain in osteoarthritis. Lancet 2005;365:965–73.

5. Aree-Ue S, Kongsombun U, Roopsawang I, Youngcharoen P. Path model of factors influencing health-related quality of life among older people with knee osteoarthritis. Nurs Health Sci 2019;

6. Felson DT. Obesity and vocational and avocational overload of the joint as risk factors for osteoarthritis. J Rheumatol Suppl 2004;70:2–5.

7. Nteeba J, Ortinau LC, Perfield JW 2nd, Keating AF. Diet-induced obesity alters immune cell infiltration and expression of inflammatory cytokine genes in mouse ovarian and peri-ovarian adipose depot tissues. Mol Reprod Dev 2013;80:948–58.

8. Rakotoarivelo V, Lacraz G, Mayhue M, Brown C, Rottembourg D, Fradette J, et al. Inflammatory Cytokine Profiles in Visceral and Subcutaneous Adipose Tissues of Obese Patients Undergoing Bariatric Surgery Reveal Lack of Correlation With Obesity or Diabetes. EBioMedicine 2018;30:237–47.

9. Coggon D, Reading I, Croft P, McLaren M, Barrett D, Cooper C. Knee osteoarthritis and obesity. Int J Obes Relat Metab Disord 2001;25:622–7.

10. Isla Pera P, Ferrer MC, Nunez Juarez M, Nunez Juarez E, Macia Soler L, Lopez Matheu C, et al. Obesity, knee osteoarthritis, and polypathology: factors favoring weight loss in older people. Patient Prefer Adherence 2016;10:957–65.

11. Lee R, Kean WF. Obesity and knee osteoarthritis. Inflammopharmacology 2012;20:53–8.

12. Marks R. Obesity profiles with knee osteoarthritis: correlation with pain, disability, disease progression. Obesity (Silver Spring) 2007;15:1867–74.

13. Salih S, Sutton P. Obesity, knee osteoarthritis and knee arthroplasty: a review. BMC Sports Sci Med Rehabil 2013;5:25.

14. Zheng H, Chen C. Body mass index and risk of knee osteoarthritis: systematic review and meta-analysis of prospective studies. BMJ Open 2015;5e007568.

15. Bliddal H, Leeds AR, Christensen R. Osteoarthritis, obesity and weight loss: evidence, hypotheses and horizons – a scoping review. Obes Rev 2014;15:578–86.

16. Bedson J, Croft PR. The discordance between clinical and radiographic knee osteoarthritis: a systematic search and summary of the literature. BMC Musculoskelet Disord 2008;9:116.

17. Spector TD, Hart DJ, Byrne J, Harris PA, Dacre JE, Doyle DV. Definition of osteoarthritis of the knee for epidemiological studies. Ann Rheum Dis 1993;52:790–4.

18. Lee KM, Kang SB, Chung CY, Park MS, Kang DW, Chang CB. Factors associated with knee pain in 5148 women aged 50 years and older: A population-based study. PLoS One 2018;13e0192478.

19. Lee S, Kim SJ. Efficacy and safety of ChondroT on knee-osteoarthritis: Protocol for a 8-week, randomized, double-blind, placebo-controlled, multicenter therapeutic exploratory clinical trial. Medicine (Baltimore) 2018;97e0170.

20. Chun MY. Validity and reliability of korean version of international physical activity questionnaire short form in the elderly. Korean J Fam Med 2012;33:144–51.

21. Bilbao A, Garcia-Perez L, Arenaza JC, Garcia I, Ariza-Cardiel G, Trujillo-Martin E, et al. Psychometric properties of the EQ-5D-5L in patients with hip or knee osteoarthritis: reliability, validity and responsiveness. Qual Life Res 2018;27:2897–908.

22. Conner-Spady BL, Marshall DA, Bohm E, Dunbar MJ, Loucks L, Al Khudairy A, et al. Reliability and validity of the EQ-5D-5L compared to the EQ-5D-3L in patients with osteoarthritis referred for hip and knee replacement. Qual Life Res 2015;24:1775–84.

23. WHO Expert Consultation. Appropriate Body-Mass Index for Asian Populations and Its Implications for Policy and Intervention Strategies. Lancet 2004;363:157–63.

24. McVinnie DS. Obesity and pain. Br J Pain 2013;7:163–70.

25. Goulston LM, Kiran A, Javaid MK, Soni A, White KM, Hart DJ, et al. Does obesity predict knee pain over fourteen years in women, independently of radiographic changes? Arthritis Care Res (Hoboken) 2011;63:1398–406.

26. Fuglestad PT, Jeffery RW, Sherwood NE. Lifestyle patterns associated with diet, physical activity, body mass index and amount of recent weight loss in a sample of successful weight losers. Int J Behav Nutr Phys Act 2012;9:79.

27. Raynor HA, Jeffery RW, Phelan S, Hill JO, Wing RR. Amount of food group variety consumed in the diet and long-term weight loss maintenance. Obes Res 2005;13:883–90.

28. Whatley JE, Gillespie WJ, Honig J, Walsh MJ, Blackburn AL, Blackburn GL. Does the amount of endurance exercise in combination with weight training and a very-low-energy diet affect resting metabolic rate and body composition? Am J Clin Nutr 1994;59:1088–92.

29. Field AE, Aneja P, Rosner B. The validity of self-reported weight change among adolescents and young adults. Obesity 2007;15:2357–64.

30. Villanueva EV. The validity of self-reported weight in US adults: a population based cross-sectional study. BMC Public Health 2001;1:11.

Article information Continued

Articles published in Kosin Medical Journal are open-access, distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

	All subjects with knee osteoarthritis (n=564)	BMI subgroups

		BMI < 23.0 kg/m²(n = 168)	23.0 kg/m² ≤ BMI ≤ 27.5 kg/m²(n = 297)	BMI>27.5 kg/m²(n = 99)	P-Value
Age (years)	68.2 (8.9)	71.4 (8.9)	67.3 (8.7)	65.6 (8.2)	<0.001
BMI (kg/m²)	24.8 (3.6)	21.1 (1.5)	25.2 (1.3)	30.2 (3.3)	<0.001
Percentage change of body weight (%)	−1.0 (4.7)	−2.3 (5.6)	−0.5 (4.2)	−0.3 (4.1)	<0.001
Kellgren-Lawrence grade (2/3/4)	257/227/80	85/63/20	154/127/45	33/48/18	0.101
Activity (weekly hours)
Vigorous intensity	0.88 (3.8)	0.88 (4.4)	0.95 (4.0)	0.67 (2.1)	0.829
Moderate intensity	1.2 (3.9)	0.86 (2.9)	1.51 (4.4)	1.1 (3.3)	0.205
Walking	3.4 (5.1)	3.5 (4.9)	3.55 (5.5)	2.5 (4.0)	0.208
Level of knee pain	2.02 (3.33)	1.85 (3.28)	1.94 (3.27)	2.57 (3.56)	0.193
EQ-5D	0.867 (0.174)	0.851 (0.208)	0.878 (0.159)	0.858 (0.148)	0.234

Level of knee pain (dependent variable)						EQ-5D (dependent variable)

	Nonstandardized		Standardized beta	t	P-Value		Nonstandardized		Standardized beta	t	V-value

	B	Standard error					B	Standard error

Age	0.026	0.016	0.069	1.639	0.102	Age	−0.004	0.001	−0.207	−5.279	<0.001
Kellgren-Lawrence grade	1.220	0.197	0.259	6.187	<0.001	Level of knee pain	−0.018	0.002	−0.341	−8.704	<0.001
Percentage change of weight	−0.026	0.029	−0.037	−0.901	0.368	Kellgren-Lawrence grade	−0.017	0.010	−0.067	−1.677	0.094
Weekly hours of walking	−0.043	0.026	−0.066	−1.613	0.107	Percentage change of weight	0.001	0.001	0.030	0.787	0.431
Coefficient	−2.896	1.097	-	−2.641	0.008	Weekly hours of vigorous activity	−0.004	0.002	−0.084	−2.231	0.026
						Weekly hours of walking	0.002	0.001	0.051	1.361	0.174
						Coefficient	1.221	0.054	-	22.816	<0.001

Level of knee pain (dependent variable)						EQ-5D (dependent variable)

	Nonstandardized		Standardized beta	t	P-Value		Nonstandardized		Standardized beta	t	P-Value

	B	Standard error					B	Standard error

BMI	−0.148	0.164	−0.067	−0.905	0.367	Age	−0.006	0.002	−0.277	−4.068	<0.001
Kellgren-Lawrence grade	1.556	0.354	0.328	4.399	<0.001	BMI	0.000	0.010	0.001	0.013	0.990
Weekly hours of walking	−0.066	0.049	−0.099	−1.361	0.175	Level of knee pain	−0.024	0.004	−0.379	−5.360	<0.001
Coefficient	1.142	3.776	-	0.302	0.763	Kellgren-Lawrence grade	−0.019	0.022	−0.063	−0.878	0.381
						Percentage change of weight	0.006	0.003	0.151	2.167	0.032
						Coefficient	1.418	0.264	-	5.369	<0.001

Level of knee pain (dependent variable)						EQ-5D (dependent variable)

	Nonstandardized		Standardized beta	t	P-Value		Nonstandardized		Standardized beta	t	P-Value

	B	Standard error					B	Standard error

Age	0.026	0.022	0.069	1.169	0.244	Age	−0.003	0.001	−0.152	−2.753	0.006
Kellgren-Lawrence grade	1.145	0.269	0.249	4.256	<0.001	Level of knee pain	−0.017	0.003	−0.355	−6.561	<0.001
Percentage change of weight	0.118	0.043	0.152	2.712	0.007	Kellgren-Lawrence grade	−0.008	0.013	−0.035	−0.615	0.539
Coefficient	−2.930	1.446	-	−2.026	0.044	Weekly hours of vigorous activity	−0.006	0.002	−0.148	−2.847	0.005
						Weekly hours of walking	0.004	0.002	0.124	2.388	0.018
						Coefficient	1.113	0.067	-	16.599	<0.001

	Level of knee pain (dependent variable)					EQ-5D (dependent variable)

	Nonstandardized		Standardized beta	t	P-Value		Nonstandardized		Standardized beta	t	P-Value

	B	Standard error					B	Standard error

Age	0.094	0.043	0.217	2.186	0.031	Age	−0.004	0.002	−0.215	−2.234	0.028
Coefficient	−3.584	2.836	-	−1.264	0.209	BMI	−0.009	0.004	−0.212	−2.293	0.024
						Level of knee pain	−0.012	0.004	−0.294	−3.238	0.002
						Kellgren-Lawrence grade	−0.023	0.020	−0.107	−1.118	0.266
						Weekly hours of moderate activity	−0.011	0.004	−0.249	−2.803	0.006
						Coefficient	1.505	0.172	-	8.749	<0.001