| | Crude model | Adjusted | OR | 95% CI | p value | OR | 95% CI | p value |
| Age (year) | | | | | | | ≤20 | Ref | | | | | | 21–30 | 0.69 | 0.43, 1.11 | 0.124 | | | | 31–40 | 0.87 | 0.52, 1.45 | 0.584 | | | | 41 and above | 0.79 | 0.46, 1.37 | 0.407 | | | | Education | | | | | | | Primary school and below | Ref | | | | | | Middle school | 0.76 | 0.52, 1.1 | 0.145 | | | | Senior high school and above | 0.91 | 0.56, 1.46 | 0.681 | | | | Marital status | | | | | | | Unmarried | Ref | | | | | | Married | 0.84 | 0.60, 1.17 | 0.296 | | | | Others | 0.78 | 0.48, 1.25 | 0.302 | | | | Monthly income | | | | | | | ≤450 | Ref | | | | | | 451–749 | 0.97 | 0.70, 1.34 | 0.837 | | | | ≥750 | 1.95 | 1.11, 3.45 | 0.021 | | | | Living status | | | | | | | Alone | Ref | | | | | | With partner | 1.20 | 0.82, 1.75 | 0.346 | | | | Others | 1.14 | 0.78, 1.66 | 0.499 | | | | Residency | | | | | | | Study city | Ref | | | Ref | | | Another city in Guangdong province | 2.03 | 1.06, 3.89 | 0.032 | 1.53 | 0.78, 3.03 | 0.217 | Another province | 1.36 | 0.93, 2.01 | 0.115 | | | | STDs related service | | | | | | | No | Ref | | | | | | Yes | 1.31 | 0.85, 2.04 | 0.225 | | | | Syphilis related knowledge | | | | | | | No | Ref | | | Ref | | | Yes | 1.45 | 1.05, 1.98 | 0.022 | 1.45 | 1.04, 2.03 | 0.028 | Condom use during the last work | | | | | | | Yes | Ref | | | | | | No | 0.98 | 0.67, 1.43 | 0.910 | | | | Frequency of condom use in the last month with clients | | | | | | | Always | Ref | | | | | | Sometimes | 1.13 | 0.82, 1.57 | 0.450 | | | | Primary sex partners | | | | | | | No | Ref | | | Ref | | | Yes | 1.67 | 1.20, 2.32 | 0.003 | 1.63 | 1.14, 2.33 | 0.008 | Condom use during the last sex with primary partners | | | | | | | Yes | Ref | | | Ref | | | No | 0.44 | 0.30, 0.66 | <.0001 | 0.47 | 0.31, 0.71 | 0.000 | Frequency of condom use in the last month with primary partners | | | | | | | Always | Ref | | | | | | Sometimes | 0.84 | 0.59, 1.21 | 0.348 | | | | STDs symptoms | | | | | | | No | Ref | | | | | | Yes | 0.77 | 0.55, 1.06 | 0.108 | | | | Drug use | | | | | | | No | Ref | | | | | | Yes | 0.68 | 0.15, 3.06 | 0.615 | | | | HIV | | | | | | | No | Ref | | | | | | Yes | 2.74 | 0.28, 26.42 | 0.384 | | | | Syphilis | | | | | | | No | Ref | | | | | | Yes | 0.58 | 0.28, 1.18 | 0.130 | | | | HCV | | | | | | | No | Ref | | | | | | Yes | 1.47 | 0.47, 4.53 | 0.506 | | | |
|
|