Table 1. Sociodemographic and clinical characteristics of the patients (N = 1212).
| Sociodemographic and clinical characteristics | n | % |
| Age (years) | ||
| ≤ 30 | 61 | 5.0 |
| 31–40 | 357 | 29.5 |
| 41–50 | 711 | 58.7 |
| >50 | 83 | 6.8 |
| Gender | ||
| Male | 934 | 77.1 |
| Female | 278 | 22.9 |
| Education attainment | ||
| No schooling and primary | 141 | 11.6 |
| Secondary | 987 | 81.4 |
| Tertiary | 84 | 6.9 |
| Marital status | ||
| Single | 229 | 18.9 |
| Married | 705 | 58.2 |
| Divorced/Widowed | 278 | 22.9 |
| Employment status | ||
| Unemployed | 594 | 49.0 |
| Employed | 618 | 51.0 |
| Average monthly income over thepast year (Chinese $) | ||
| <1000 | 708 | 58.4 |
| 1000–2999 | 307 | 25.3 |
| ≥ 3000 | 197 | 16.3 |
| Chronic disease | ||
| Yes | 616 | 50.8 |
| No | 596 | 49.2 |
| Days of methadone intake | ||
| ≤ 90 | 69 | 5.7 |
| 91–180 | 93 | 7.7 |
| 181–365 | 170 | 14.0 |
| >365 | 880 | 72.6 |
| Average daily dose of methadone intake (mg) | ||
| ≤ 20 | 23 | 1.9 |
| 21–60 | 886 | 73.1 |
| >60 | 303 | 25.0 |