| total | average age | gender | ||
| male | female | |||
| The study group | 687 | 47.25 ± 14.31 | 448 | 239 |
| The control group | 672 | 52.7 ± 24.62 | 417 | 255 |
| P value | P > 0.05 | P > 0.05 | ||