Table 1 Characteristic of study sample with and without arthritis

Age (years)

47.99 ± 9.36

37.59 ± 11.34

< 0.001

 20–29 years

5.97

30.31

< 0.001

 30–39 years

12.38

26.12

 40–49 years

27.09

24.53

 50–59 years

54.56

19.04

 Male

43.92

53.83

< 0.001

 Female

56.08

46.17

 Mexican American

6.07

11.06

< 0.001

 Other Hispanic

5.07

7.71

 Non-Hispanic White

68.41

58.80

 Non-Hispanic Black

12.47

12.32

 Other race—including multi-racial

7.97

10.11

 Less than 9th grade

3.94

3.96

< 0.001

 9th–11th grade

11.83

9.02

 High school graduate/GED or equivalent

22.99

21.67

 Some college or AA degree

35.13

32.47

 College graduate or above

26.11

32.87

 Not recorded

0

0.01

 Body mass index (kg/m2)

31.71 ± 8.00

28.56 ± 6.56

< 0.001

 Ratio of family income to poverty

2.95 ± 1.72

2.94 ± 1.66

0.821

 Yes

19.99

36.63

< 0.001

 No

80.01

63.37

 Yes

51.38

38.63

< 0.001

 No

48.59

61.35

 Not recorded

0.03

0.02

Blood urea nitrogen (mmol/L)

4.82 ± 1.71

4.54 ± 1.49

< 0.001

Total protein (g/L)

70.60 ± 4.45

71.58 ± 4.29

< 0.001

Total cholesterol (mmol/L)

5.11 ± 1.04

4.91 ± 1.02

< 0.001

Alkaline phosphatase (U/L)

71.50 ± 22.57

66.32 ± 22.73

< 0.001

Serum uric acid(μmol/L)

323.79 ± 84.78

318.53 ± 80.72

0.019

Serum sodium (mmol/L)

139.12 ± 2.43

139.25 ± 2.21

0.037

Serum potassium (mmol/L)

3.95 ± 0.33

3.97 ± 0.31

0.122

Serum phosphorus (mmol/L)

1.20 ± 0.17

1.20 ± 0.18

0.397

Serum calcium (mmol/L)

2.34 ± 0.09

2.34 ± 0.08

0.013

Disease duration of arthritis (years)

9.20 ± 8.90

/

 Osteoarthritis or degenerative arthritis

41.61

/

/

 Rheumatoid arthritis

17.45

/

 Psoriatic arthritis

2.73

/

 Other

0.17

/

 Do not know or refused

24.20

/

Lumbar bone mineral density (g/cm²)

1.05 ± 0.16

1.04 ± 0.15

0.086