Table 3 Sample Characteristics by Pain Trajectory Group

Age, mean year ± SD

63.7 ± 7.0

59.3 ± 8.8

56.8 ± 6.5

54.3 ± 6.7

Low > High & Moderate-High (p < 0.001)

Moderate-Low > High (p = 0.014)

Gender, %

 Female

72.7%

66.7%

52.6%

77.4%

 Male

27.3%

33.3%

47.45

22.6%

Ethnicity/Race, %

 Non-Hispanic Black

0%

40.4%

65.4%

74.2%

 Non-Hispanic White

100%

59.6%

34.6%

25.8%

Highest Education Level, %(n)

 Some high school

0%

1.8%

7.7%

19.4%

 High school degree

13.6%

26.3%

56.4%

51.6%

 Two-year college degree

27.3%

12.3%

21.8%

9.7%

 Four-year college degree

31.8%

31.6%

9.0%

16.1%

 Master’s or Doctoral degree

27.3%

28.1%

5.1%

3.2%

Household Income, %(n)

 $0 - $19,999

19.1%

19.6%

52.0%

80.0%

 $20,000 - $39,999

9.5%

25.0%

20.8%

6.7%

 $40,000 - $59,999

19.1%

25.0%

14.3%

0%

 $60,000 - $99,999

33.3%

14.3%

10.4%

6.7%

 $100,000+

19.1%

16.1%

2.6%

6.7%

BMI, mean ± SD

27.9 ± 5.8

31.4 ± 5.8

31.5 ± 6.9

37.7 ± 10.5

High > all other groups, p < 0.001

Kellgren-Lawrence (KL) Score, %(n)

 0

27.3%

37.5%

27.6%

20.0%

 1

31.8%

19.6%

11.8%

6.7%

 2

9.1%

19.6%

30.3%

6.7%

 3

13.6%

12.5%

15.8%

26.7%

 4

18.2%

10.7%

14.5%

40.0%

 Frequency: Currently experiencing knee pain on most days, % yes

27.3%

40.4%

47.4%

77.4%

 Intensity: GCPS (0–100), mean ± SD

31.5 ± 12.2

45.1 ± 18.1

61.4 ± 20.3

78.5 ± 17.1

All pairwise comparisons p < 0.05

 Time/Duration:

  < 6 months

4.6%

3.6%

9.0%

0%

  6 months to 1 year

9.1%

3.6%

9.0%

12.9%

  1 to 3 years

22.7%

25.0%

20.5%

38.7%

  3 to 5 years

13.6%

17.9%

12.8%

12.9%

  > 5 years

50.0%

50.0%

48.7%

35.8%

Pain Sites: Number of body sites with pain, mean ± SD

4.0 ± 2.7

5.1 ± 3.2

6.1 ± 3.4

7.0 ± 4.7

High > Low, p = 0.015

WOMAC total score

16.8 ± 10.8

27.7 ± 14.9

39.2 ± 18.0

57.2 ± 16.1

All pairwise comparisons p < 0.05