Table 1.
Demographic characteristics of the studied cohort (n = 136,720)
| Characteristic* | No. of subjects | % |
| Gender | ||
| Male | 68,135 | 49.8 |
| Female | 68,585 | 50.2 |
| Age (years) | ||
| 2–7 | 9,648 | 7.1 |
| 8–14 | 11,933 | 8.7 |
| 15–24 | 23,244 | 17.0 |
| 25–34 | 26,903 | 19.7 |
| 35–44 | 27,307 | 20.0 |
| 45–54 | 17,273 | 12.6 |
| 55–64 | 9,986 | 7.3 |
| ≥ 65 | 10,426 | 7.6 |
| Socio-economic status | ||
| < US$640 | 54,729 | 40.0 |
| US$640-1279 | 29,788 | 21.8 |
| ≥ US$1280 | 11,137 | 8.1 |
| Farmers and fishermen | 21,568 | 15.8 |
| Others | 19,498 | 14.3 |
| Severe disease | ||
| Without | 132,835 | 97.2 |
| With | 3,885 | 2.8 |
| Region | ||
| Taipei | 43,392 | 31.7 |
| Northern Taiwan | 18,830 | 13.8 |
| Central Taiwan | 26,732 | 19.6 |
| Southern Taiwan | 21,241 | 15.5 |
| Kaohsiung and Pingtung | 22,848 | 16.7 |
| East Taiwan | 3,677 | 2.7 |
| Remote Area | ||
| Mountainous regions | 1,159 | 0.9 |
| Offshore islands | 1,156 | 0.9 |
| General Population | 134,405 | 98.2 |
*Determined from 1997 prospectively.