Table 1.
Baseline characteristics of the study population
| Characteristic | Male (N=938) |
Female (N=1,054) |
||||||
|---|---|---|---|---|---|---|---|---|
| Group 1 (n=622) | Group 2 (n=250) | Group 3 (n=66) | P-value | Group 1 (n=759) | Group 2 (n=177) | Group 3 (n=118) | P-value | |
| Age (y) | 49.3±0.3 | 50.6±0.5 | 50.7±1.0 | 0.036 | 47.3±0.3 | 48.1±0.6 | 49.1±0.8 | 0.050 |
| Height (cm) | 169.6±0.3 | 168.9±0.4 | 169.1±0.6 | 0.403 | 157.8±0.2 | 157.2±0.4 | 156.9±0.6 | 0.190 |
| Weight (kg) | 60.7±0.3 | 62.0±0.4 | 62.7±0.8 | 0.003 | 52.7±0.2 | 53.5±0.4 | 54.2±0.4 | 0.003 |
| BMI (kg/m2) | 21.1±0.1 | 21.7±0.1 | 21.9±0.2 | <0.001 | 21.1±0.1 | 21.6±0.1 | 22.0±0.1 | <0.001 |
| Waist circumference (cm) | 76.5±0.2 | 80.4±0.3 | 82.0±0.6 | <0.001 | 72.4±0.2 | 74.5±0.5 | 76.0±0.6 | <0.001 |
| Income* | 0.933 | 0.732 | ||||||
| Q1 | 77 (12.3) | 23 (6.6) | 7 (14.1) | 81 (11.1) | 20 (9.4) | 14 (11.2) | ||
| Q2 | 151 (24.9) | 67 (29.5) | 19 (33.8) | 174 (26.8) | 39 (24.8) | 29 (27.8) | ||
| Q3 | 203 (33.4) | 76 (29.7) | 25 (32.3) | 243 (29.9) | 54 (34.3) | 25 (18.1) | ||
| Q4 | 186 (29.4) | 82 (34.1) | 15 (19.8) | 254 (32.2) | 60 (31.5) | 49 (42.9) | ||
| Education† | 0.060 | 0.407 | ||||||
| Low | 119 (17.7) | 44 (16.5) | 10 (14.1) | 117 (13.7) | 35 (19.7) | 24 (20.0) | ||
| Middle | 350 (55.3) | 128 (50.0) | 35 (49.6) | 456 (61.2) | 95 (53.3) | 65 (52.1) | ||
| High | 153 (27.0) | 78 (33.6) | 21 (36.3) | 186 (25.0) | 47 (27.0) | 29 (27.9) | ||
| Smoking | 0.070 | 0.669 | ||||||
| None | 114 (19.5) | 49 (16.1) | 14 (20.2) | 710 (93.5) | 166 (95.0) | 111 (93.3) | ||
| Past | 187 (27.6) | 91 (39.2) | 24 (35.2) | 16 (2.1) | 4 (1.7) | 3 (3.2) | ||
| Current | 321 (52.9) | 109 (44.7) | 28 (44.6) | 32 (4.4) | 6 (3.3) | 4 (3.5) | ||
| Alcohol | 0.732 | 0.001 | ||||||
| None | 90 (13.3) | 31 (14.1) | 8 (10.8) | 214 (27.2) | 64 (33.6) | 51 (38.7) | ||
| Mild to moderate | 431 (70.5) | 189 (73.5) | 49 (71.5) | 527 (71.1) | 110 (65.6) | 64 (58.7) | ||
| Heavy | 101 (16.2) | 30 (12.5) | 9 (17.7) | 16 (1.7) | 2 (0.8) | 3 (2.6) | ||
| Physical activity | 0.001 | 0.156 | ||||||
| None | 404 (66.8) | 190 (75.7) | 50 (80.3) | 544 (69.8) | 135 (75.6) | 89 (72.9) | ||
| Light | 106 (15.7) | 42 (17.5) | 6 (6.0) | 126 (17.4) | 26 (15.0) | 19 (17.9) | ||
| Vigorous | 112 (17.5) | 18 (6.8) | 10 (13.8) | 89 (12.8) | 16 (9.4) | 10 (9.2) | ||
| Postmenopausal women | - | - | - | - | 229 (27.4) | 80 (42.0) | 52 (35.2) | 0.005 |
| Vitamin D (ng/mL) | 18.57±1.20 | 19.48±0.57 | 20.59±0.40 | 0.093 | 16.20±0.62 | 16.00±0.50 | 16.40±0.27 | 0.765 |
| Bone mineral density | ||||||||
| Total hip (g/cm2) | 0.993±0.005 | 0.911±0.007 | 0.873±0.013 | <0.001 | 0.856±0.005 | 0.843±0.011 | 0.825±0.010 | 0.016 |
| Femoral neck (g/cm2) | 0.778±0.005 | 0.751±0.007 | 0.732±0.012 | <0.001 | 0.712±0.004 | 0.703±0.012 | 0.683±0.010 | 0.024 |
| Lumbar spine (g/cm2) | 0.933±0.007 | 0.926±0.009 | 0.901±0.014 | 0.119 | 0.931±0.006 | 0.901±0.013 | 0.905±0.013 | 0.033 |
| Whole body (g/cm2) | 1.172±0.005 | 1.151±0.009 | 1.117±0.014 | <0.001 | 1.117±0.006 | 1.082±0.009 | 1.071±0.012 | <0.001 |
Values are presented as mean±standard error or number (%). P-values were obtained by analysis of variance and chi-square tests (linear-by-linear association). The group was divided according to total body fat percentage. The cutoff values were 20.6% and 25.7% for men with a BMI of 18.5–22.9 kg/m2 and 33.4% and 36.0% for women. Women: group 1, <20.6%; group 2, 20.6% to 25.7%; group 3, ≥25.7%; men: group 1, <33.4%; group 2, 33.4% to <36.0%; group 3, ≥36.0%.
BMI, body mass index.
*
Monthly average income was divided into quartiles.
†
Low, <9 years; middle, 9 to <14 years; high, ≥14 years.