Table 1 Characteristic of study sample with and without arthritis.
|
Arthritis (n=1510)
|
Non-arthritis(n=9584)
|
P value
|
Age (years)
|
47.99 ± 9.36
|
37.59 ± 11.34
|
<0.0001
|
Age groups
|
|
|
<0.0001
|
20-29 years
|
5.97
|
30.31
|
|
30-39 years
|
12.38
|
26.12
|
|
40-49 years
|
27.09
|
24.53
|
|
50-59 years
|
54.56
|
19.04
|
|
Gender (%)
|
|
|
<0.0001
|
Male
|
43.92
|
53.83
|
|
Female
|
56.08
|
46.17
|
|
Race (%)
|
|
|
<0.0001
|
Mexican American
|
6.07
|
11.06
|
|
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
|
|
Educational level (%)
|
|
|
<0.0001
|
Less than 9th grade
|
3.94
|
3.96
|
|
9-11th 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
|
<0.0001
|
Ratio of family income to poverty
|
2.95 ± 1.72
|
2.94 ± 1.66
|
0.8213
|
Vigorous recreational activities (%)
|
|
|
<0.0001
|
Yes
|
19.99
|
36.63
|
|
No
|
80.01
|
63.37
|
|
Smoked at least 100 cigarettes in life (%)
|
|
|
<0.0001
|
Yes
|
51.38
|
38.63
|
|
No
|
48.59
|
61.35
|
|
Not recorded
|
0.03
|
0.02
|
|
Blood urea nitrogen ((mmol/L)
|
4.82 ± 1.71
|
4.54 ± 1.49
|
<0.0001
|
Total protein (g/L)
|
70.60 ± 4.45
|
71.58 ± 4.29
|
<0.0001
|
Total cholesterol ((mmol/L)
|
5.11 ± 1.04
|
4.91 ± 1.02
|
<0.0001
|
Alkaline phosphatase (U/L)
|
71.50 ± 22.57
|
66.32 ± 22.73
|
<0.0001
|
Serum uric acid(umol/L)
|
323.79 ± 84.78
|
318.53 ± 80.72
|
0.0191
|
Serum sodium (mmol/L)
|
139.12 ± 2.43
|
139.25 ± 2.21
|
0.0369
|
Serum potassium (mmol/L)
|
3.95 ± 0.33
|
3.97 ± 0.31
|
0.1215
|
Serum phosphorus (mmol/L)
|
1.20 ± 0.17
|
1.20 ± 0.18
|
0.3971
|
Serum calcium (mmol/L)
|
2.34 ± 0.09
|
2.34 ± 0.08
|
0.0129
|
Disease duration of arthritis (years)
|
9.20 ± 8.90
|
/
|
|
Which type of arthritis was it? (%)
|
|
|
/
|
Osteoarthritis or degenerative arthritis
|
41.61
|
/
|
|
Rheumatoid arthritis
|
17.45
|
/
|
|
Psoriatic arthritis
|
2.73
|
/
|
|
Other
|
0.17
|
/
|
|
Don't know or refused
|
24.20
|
/
|
|
Lumbar bone mineral density (g/cm2)
|
1.05 ± 0.16
|
1.04 ± 0.15
|
0.0861
|
Mean ± SD for continuous variables: P value was calculated by weighted linear regression model.
% for categorical variables: P value was calculated by weighted chi-square test.
Table 2 Associations between arthritis and lumbar bone mineral density.
|
Model 1 β (95% CI, P)
|
Model 2 β (95% CI, P)
|
Model 3 β (95% CI, P)
|
Non- Arthritis
|
Reference
|
Reference
|
Reference
|
Arthritis
|
0.007 (-0.001, 0.015) 0.0861
|
0.017 (0.008, 0.025) 0.0001
|
0.018 (0.010, 0.027) <0.0001
|
Non- Arthritis
|
Reference
|
Reference
|
Reference
|
Osteoarthritis or degenerative arthritis
|
0.013 (0.001, 0.025) 0.0293
|
0.023 (0.012, 0.035) 0.0001
|
0.023 (0.011, 0.035) 0.0001
|
Rheumatoid arthritis
|
0.000 (-0.017, 0.018) 0.9733
|
0.010 (-0.007, 0.027) 0.2599
|
0.014 (-0.003, 0.031) 0.1074
|
Psoriatic arthritis
|
0.005 (-0.039, 0.049) 0.8177
|
0.020 (0.000, 0.039) 0.0445
|
0.024 (0.005, 0.043) 0.0133
|
Don't know or refused
|
0.000 (-0.015, 0.015) 0.9712
|
0.008 (-0.006, 0.023) 0.2665
|
0.011 (-0.004, 0.026) 0.1350
|
Model 1: no covariates were adjusted.
Model 2: age, gender, race were adjusted.
Model 3: age, gender, race, educational level, body mass index, ratio of family income to poverty, vigorous recreational activities, smoked at least 100 cigarettes in life, blood urea nitrogen, total protein, total cholesterol, alkaline phosphatase, serum uric acid, serum sodium, serum potassium, serum phosphorus, and serum calcium were adjusted.
Table 3 Subgroup analyses stratified by gender.
|
Model 1 β (95% CI, P)
|
Model 2 β (95% CI, P)
|
Model 3 β (95% CI, P)
|
Male
|
|
|
|
Non- Arthritis
|
Reference
|
Reference
|
Reference
|
Osteoarthritis or degenerative arthritis
|
0.045 (0.026, 0.065) <0.0001
|
0.053 (0.034, 0.072) <0.0001
|
0.047 (0.028, 0.066) <0.0001
|
Rheumatoid arthritis
|
0.010 (-0.016, 0.036) 0.4569
|
0.021 (-0.005, 0.046) 0.1139
|
0.023 (-0.003, 0.048) 0.0776
|
Female
|
|
|
|
Non- Arthritis
|
Reference
|
Reference
|
Reference
|
Osteoarthritis or degenerative arthritis
|
-0.012 (-0.026, 0.003) 0.1158
|
0.005 (-0.010, 0.020) 0.4922
|
0.007 (-0.008, 0.021) 0.3526
|
Rheumatoid arthritis
|
-0.010 (-0.034, 0.013) 0.3941
|
0.001 (-0.022, 0.024) 0.9418
|
0.008 (-0.015, 0.031) 0.5157
|
Associations were adjusted for age, race, educational level, body mass index, ratio of family income to poverty, vigorous recreational activities, smoked at least 100 cigarettes in life, blood urea nitrogen, total protein, total cholesterol, alkaline phosphatase, serum uric acid, serum sodium, serum potassium, serum phosphorus, and serum calcium.
Table 4 Subgroup analyses stratified by race.
|
Model 1 β (95% CI, P)
|
Model 2 β (95% CI, P)
|
Model 3 β (95% CI, P)
|
Non-Hispanic White
|
|
|
|
Non- Arthritis
|
Reference
|
Reference
|
Reference
|
Osteoarthritis or degenerative arthritis
|
0.009 (-0.009, 0.026) 0.3439
|
0.018 (-0.000, 0.036) 0.0501
|
0.019 (0.001, 0.037) 0.0382
|
Rheumatoid arthritis
|
-0.015 (-0.045, 0.015) 0.3222
|
-0.007 (-0.036, 0.023) 0.6699
|
0.001 (-0.028, 0.031) 0.9232
|
Non-Hispanic Black
|
|
|
|
Non- Arthritis
|
Reference
|
Reference
|
Reference
|
Osteoarthritis or degenerative arthritis
|
-0.020 (-0.050, 0.009) 0.1806
|
0.003 (-0.027, 0.034) 0.8340
|
0.007 (-0.024, 0.037) 0.6611
|
Rheumatoid arthritis
|
0.008 (-0.031, 0.046) 0.6947
|
0.032 (-0.007, 0.071) 0.1105
|
0.032 (-0.007, 0.071) 0.1035
|
Mexican American
|
|
|
|
Non- Arthritis
|
Reference
|
Reference
|
Reference
|
Osteoarthritis or degenerative arthritis
|
0.015 (-0.025, 0.056) 0.4579
|
0.032 (-0.008, 0.073) 0.1189
|
0.017 (-0.023, 0.057) 0.4103
|
Rheumatoid arthritis
|
-0.022 (-0.061, 0.018) 0.2899
|
-0.004 (-0.044, 0.036) 0.8602
|
-0.006 (-0.046, 0.033) 0.7621
|
Associations were adjusted for age, gender, educational level, body mass index, ratio of family income to poverty, vigorous recreational activities, smoked at least 100 cigarettes in life, blood urea nitrogen, total protein, total cholesterol, alkaline phosphatase, serum uric acid, serum sodium, serum potassium, serum phosphorus, and serum calcium.
Table 5 Associations between disease duration of arthritis and lumbar bone mineral density.
Disease duration of arthritis (years)
|
Model 1
β (95% CI) P value
|
Model 2
β (95% CI) P value
|
Model 3
β (95% CI) P value
|
Osteoarthritis or degenerative arthritis
|
0.0005 (-0.0021, 0.0011) 0.5312
|
-0.0003 (-0.0020, 0.0013) 0.6746
|
-0.0001 (-0.0017, 0.0015) 0.8619
|
|
Rheumatoid arthritis
|
0.0013 (-0.0005, 0.0032) 0.1596
|
0.0013 (-0.0005, 0.0032) 0.1649
|
0.0006 (-0.0012, 0.0025) 0.4979
|
Associations were adjusted for age, race, educational level, body mass index, ratio of family income to poverty, vigorous recreational activities, smoked at least 100 cigarettes in life, blood urea nitrogen, total protein, total cholesterol, alkaline phosphatase, serum uric acid, serum sodium, serum potassium, serum phosphorus, and serum calcium.