Table 1 Characteristics of study populations
Variables | Total (n = 2,711) | Urban (n = 1,363) | Rural (n = 1,348) | Statistics | P |
|---|---|---|---|---|---|
Gender, n (%) |  |  |  | χ2 = 0.211 | 0.646 |
 Males | 1171 (49.51) | 590 (50.68) | 581 (48.67) |  |  |
 Females | 1540 (50.49) | 773 (49.32) | 767 (51.33) |  |  |
Age (years), n (%) |  |  |  | χ2 = 7.976 | 0.240 |
 20–29 | 181 (21.32) | 91 (25.18) | 90 (18.50) |  |  |
 30–39 | 184 (18.99) | 93 (20.29) | 91 (18.05) |  |  |
 40–49 | 578 (23.28) | 302 (22.05) | 276 (24.18) |  |  |
 50–59 | 686 (16.60) | 347 (15.36) | 339 (17.50) |  |  |
 60–69 | 798 (11.06) | 407 (9.75) | 391 (12.02) |  |  |
 70–79 | 255 (7.75) | 113 (6.43) | 142 (8.71) |  |  |
 80–89 | 29 (1.00) | 10 (0.94) | 19 (1.04) |  |  |
 BMI (kg/m2), mean (S.E) | 24.36 (0.15) | 24.12 (0.27) | 24.54 (0.16) | t = -1.35 | 0.177 |
BMI (kg/m2), n (%) |  |  |  | χ2 = 7.389 | 0.025 |
 Underweight (< 18.5) | 58 (3.21) | 22 (2.37) | 36 (3.82) |  |  |
 Normal (18.5–23.9) | 1078 (46.06) | 532 (52.02) | 546 (41.72) |  |  |
 Overweight (≥ 24.0) | 1575 (50.73) | 809 (45.61) | 766 (54.47) |  |  |
Osteoporosis, n (%) |  |  |  | χ2 = 16.188 |  < 0.001 |
 No | 2340 (91.70) | 1202 (94.48) | 1138 (89.67) |  |  |
 Yes | 371 (8.30) | 161 (5.52) | 210 (10.33) |  |  |
Low BMD, n (%) |  |  |  | χ2 = 5.232 | 0.022 |
 No | 1658 (66.79) | 861 (71.91) | 797 (63.05) |  |  |
 Yes | 1053 (33.21) | 502 (28.09) | 551 (36.95) |  |  |
 Lumbar spine L1 (g/cm2), mean (S.E) | 0.91 (0.01) | 0.95 (0.01) | 0.87 (0.01) | t = 7.20 |  < 0.001 |
 Lumbar spine L2 (g/cm2), mean (S.E) | 0.99 (0.01) | 1.02 (0.01) | 0.96 (0.01) | t = 4.98 |  < 0.001 |
 Lumbar spine L3 (g/cm2), mean (S.E) | 1.05 (0.01) | 1.09 (0.01) | 1.02 (0.01) | t = 5.77 |  < 0.001 |
 Lumbar spine L4 (g/cm2), mean (S.E) | 1.05 (0.01) | 1.08 (0.01) | 1.03 (0.01) | t = 3.66 |  < 0.001 |
 Greater trochanter (g/cm2), mean (S.E) | 0.64 (0.00) | 0.65 (0.01) | 0.63 (0.00) | t = 2.20 | 0.028 |
 Total hip (g/cm2), mean (S.E) | 0.88 (0.01) | 0.88 (0.01) | 0.87 (0.01) | t = 0.77 | 0.441 |