Table 1 Demographic characteristics of the study participants
Variables | Total sample | Subsample 1 | Subsample 2 |
|---|---|---|---|
(N = 561) | (N = 281) | (N = 280) | |
n (%) | n (%) | n (%) | |
Gender | |||
 Female | 520 (92.7) | 268 (95.4) | 252 (90.0) |
 Male | 41 (7.3) | 13 (4.6) | 28 (10.0) |
Age (Years) | |||
 18 ~ 30 | 66 (11.8) | 34 (12.1) | 32 (11.4) |
 31 ~ 50 | 241 (43.0) | 139 (49.5) | 102 (36.4) |
 51 ~ 70 | 236 (42.0) | 99 (35.2) | 137 (48.9) |
  > 70 | 18 (3.2) | 9 (3.2) | 9 (3.2) |
Education | |||
 Bachelor’s degree or above | 171 (30.5) | 99 (50.9) | 72 (25.7) |
 High school degree | 95 (16.9) | 48 (17.1) | 47 (16.8) |
 Junior middle school degree | 180 (32.1) | 80 (28.5) | 100 (35.7) |
 Primary school degrees or below | 115 (20.5) | 54 (19.2) | 61 (21.8) |
Living | |||
 Cities | 379 (67.6) | 195 (69.4) | 184 (65.7) |
 Towns and rural | 182 (32.5) | 86 (30.6) | 96 (34.3) |
Smoking status | |||
 Never smoking | 522 (93.1) | 267 (95.0) | 255 (91.1) |
 Yes, but having quit smoking | 18 (3.2) | 7 (2.5) | 11 (3.9) |
 Yes, still smoking | 21 (3.7) | 7 (2.5) | 14 (5.0) |
Joint deformation | |||
 Yes | 283 (49.6) | 152 (54.1) | 149 (53.2) |
 No | 278 (50.4) | 129 (45.9) | 131 (46.8) |
|  | Mean ± SD | Mean ± SD | Mean ± SD |
Age (Years) | 47.88 ± 12.88 | 46.28 ± 12.47 | 49.49 ± 13.08 |