Demographic characteristics
A total of 21,596 FSWs were recruited in this study over nine years. The demographic characteristics were shown in Table 1. Among all the participants, 19,873 (92.0%) were LCFSWs and 1,723 (8.0%) were CMFSWs. It is worth noting that all of the CMFSWs in our study were from Vietnam. Additionally, results showed that CMFSWs were more likely to be unmarried, divorced or widowed, receiving less than 6 years of education, working in low-tier venues, reporting a shorter time of staying in current residence, a shorter length time as a commercial sex worker and a younger age at commercial sexual debut than LCFSWs.
Table 1
Demographic characteristics of local Chinese and cross-border migrant FSWs (%)
Variables
|
2010
N = 1680
|
2011
N = 2366
|
2012
N = 2461
|
2013
N = 3350
|
2014
N = 3197
|
2015
N = 3239
|
2016
N = 1061
|
2017
N = 2185
|
2018
N = 2057
|
All
N = 21596
|
χ2
|
P
|
LC
|
CM
|
LC
|
CM
|
LC
|
CM
|
LC
|
CM
|
LC
|
CM
|
LC
|
CM
|
LC
|
CM
|
LC
|
CM
|
LC
|
CM
|
LC
|
CM
|
Working venues
|
24.7
|
< 0.001
|
Low-tier
|
89.1
|
78.6
|
93.9
|
83.1
|
92.5
|
92.3
|
89.7
|
96.5
|
90.2
|
99.3
|
89.8
|
94.7
|
52.3
|
43.9
|
43.4
|
80.6
|
40.5
|
68.7
|
79.8
|
84.8
|
|
|
High-tier
|
10.9
|
21.4
|
6.1
|
16.9
|
7.5
|
7.7
|
10.3
|
3.5
|
9.8
|
0.7
|
10.2
|
5.3
|
47.7
|
56.1
|
56.6
|
19.4
|
59.5
|
31.3
|
20.2
|
15.2
|
|
|
Age
|
3.2
|
0.075
|
> 35 years old
|
15.3
|
21.4
|
16.3
|
16.7
|
19.7
|
16.2
|
26.2
|
14.5
|
27.0
|
27.7
|
25.5
|
22.5
|
46.2
|
28.8
|
37.6
|
31.8
|
40.6
|
32.7
|
26.7
|
24.8
|
|
|
≤ 35 years old
|
84.7
|
78.6
|
83.7
|
83.3
|
80.3
|
83.8
|
73.8
|
85.5
|
73.0
|
72.3
|
74.5
|
77.5
|
53.8
|
71.2
|
62.4
|
68.2
|
59.4
|
67.3
|
73.3
|
75.2
|
|
|
Marital status
|
11.9
|
0.001
|
Married/cohabiting
|
52.0
|
35.7
|
56.2
|
43.9
|
60.7
|
43.8
|
60.9
|
47.3
|
62.6
|
59.5
|
65.5
|
55.7
|
64.9
|
66.9
|
64.4
|
69.9
|
70.7
|
65.4
|
62.0
|
57.7
|
|
|
Unmarried/divorced/widowed
|
48.0
|
64.3
|
43.8
|
56.1
|
39.3
|
56.2
|
39.1
|
52.7
|
37.4
|
40.5
|
34.5
|
44.3
|
35.1
|
33.1
|
35.6
|
30.1
|
29.3
|
34.6
|
38.0
|
42.3
|
|
|
Years of education
|
200.4
|
< 0.001
|
< 6 years
|
33.3
|
50.0
|
28.7
|
48.5
|
29.4
|
47.7
|
29.7
|
35.3
|
28.5
|
49.3
|
34.8
|
39.7
|
48.6
|
14.4
|
33.8
|
46.8
|
33.5
|
49.5
|
32.0
|
42.2
|
|
|
6–9 years
|
59.1
|
50.0
|
61.7
|
40.9
|
63.8
|
49.2
|
61.3
|
53.4
|
65.8
|
40.2
|
58.4
|
37.0
|
46.7
|
47.5
|
58.9
|
47.2
|
55.1
|
36.0
|
60.5
|
44.1
|
|
|
> 9 years
|
7.6
|
0.0
|
9.6
|
10.6
|
6.8
|
3.1
|
9.0
|
11.3
|
5.7
|
10.5
|
6.8
|
23.3
|
4.7
|
38.1
|
7.3
|
6.0
|
8.4
|
14.5
|
7.5
|
13.7
|
|
|
Months of staying in current residence
|
153.2
|
< 0.001
|
> 12 months
|
41.2
|
61.9
|
37.1
|
33.3
|
48.2
|
50.8
|
41.4
|
27.6
|
42.1
|
34.1
|
37.5
|
23.7
|
50.2
|
19.4
|
46.9
|
42.8
|
54.0
|
31.8
|
43.3
|
33.4
|
|
|
6 ~ 12 months
|
17.0
|
14.3
|
18.8
|
12.1
|
18.9
|
18.0
|
17.9
|
14.6
|
21.3
|
16.6
|
20.8
|
11.8
|
10.5
|
7.9
|
21.5
|
15.4
|
20.5
|
12.6
|
19.2
|
14.0
|
|
|
< 6 months
|
41.8
|
23.8
|
44.1
|
54.6
|
32.9
|
31.2
|
40.7
|
57.8
|
36.6
|
49.3
|
41.7
|
64.5
|
39.3
|
72.7
|
31.6
|
41.8
|
25.5
|
55.6
|
37.5
|
52.6
|
|
|
Age of commercial sexual debut
|
14.0
|
< 0.001
|
≥ 18 years old
|
—
|
—
|
—
|
—
|
—
|
—
|
—
|
—
|
—
|
—
|
—
|
—
|
98.4
|
92.1
|
98.6
|
98.0
|
98.1
|
96.3
|
98.3
|
96.2
|
|
|
< 18 years old
|
—
|
—
|
—
|
—
|
—
|
—
|
—
|
—
|
—
|
—
|
—
|
—
|
1.6
|
7.9
|
1.4
|
2.0
|
1.9
|
3.7
|
1.7
|
3.8
|
|
|
Years of experience as FSW
|
106.6
|
< 0.001
|
> 5 years
|
—
|
—
|
—
|
—
|
—
|
—
|
—
|
—
|
—
|
—
|
—
|
—
|
37.2
|
7.9
|
31.5
|
16.1
|
34.6
|
14.5
|
33.8
|
13.8
|
|
|
≤ 5 years
|
—
|
—
|
—
|
—
|
—
|
—
|
—
|
—
|
—
|
—
|
—
|
—
|
62.8
|
92.1
|
68.5
|
83.9
|
65.4
|
85.5
|
66.2
|
86.2
|
|
|
Months of staying in the same venue
|
1.7
|
0.196
|
> 12 months
|
—
|
—
|
—
|
—
|
—
|
—
|
—
|
—
|
—
|
—
|
—
|
—
|
30.5
|
33.1
|
18.9
|
15.4
|
19.0
|
14.9
|
21.2
|
19.0
|
|
|
≤ 12 months
|
—
|
—
|
—
|
—
|
—
|
—
|
—
|
—
|
—
|
—
|
—
|
—
|
69.5
|
66.9
|
81.1
|
84.6
|
81.0
|
85.1
|
78.8
|
81.0
|
|
|
Abbreviations: LC, local Chinese; CM, cross-border migrant; FSWs, female sex workers.
|
Prevalence of HIV-1, syphilis and HCV infection
The overall prevalence of HIV-1 and syphilis infection among all the participants was 0.91% (197/21596) and 5.14% (1109/21596), respectively, and remained relatively stable during the study period. However, as shown in Fig. 1, the HIV-1 prevalence among LCFSWs significantly decreased from 2010 to 2018 (OR = 0.922, 95% CI: 0.859–0.989; p for trend = 0.024), but this trend was not found among CMFSWs. Furthermore, higher HIV-1 and HCV prevalence was observed among CMFSWs than LCFSWs (HIV-1: 3.13% versus 0.72%, p < 0.001; HCV: 2.09% versus 1.05%, p < 0.001), though HCV prevalence significantly decreased among CMFSWs from 2010 to 2018 (OR = 0.845, 95% CI: 0.726–0.983; p for trend = 0.029). There was no statistical difference in the prevalence of syphilis infection between LCFSWs and CMFSWs (5.15% versus 4.93%, p = 0.838), and there was no significant change in the trend of syphilis infection of the two groups.
Behavioural characteristics and self-reporting of STIs
As shown in Table 2, compared to LCFSWs, CMFSWs were more likely to use illicit drugs, sex with regular commercial sexual partners in the past month, but less likely to use condoms in last commercial sex and in the last month, have steady non-paying sexual partners and sex with commercial male clients who used aphrodisiac drugs. The proportion of participants who insisted on using condoms in last commercial sex and in last month were both gradually increased among LCFSWs (OR = 1.364, 95% CI: 1.315–1.415; OR = 1.344, 95% CI: 1.319–1.369) and CMFSWs (OR = 1.242, 95% CI: 1.122–1.375; OR = 1.123, 95% CI: 1.061–1.188). History of illicit drugs use was gradually increased among LCFSWs (OR = 1.075, 95% CI: 1.020–1.134), while it was gradually decreased among CMFSWs (OR = 0.771, 95% CI: 0.666–0.892). Downward trends were also found in the number of male clients in the past month (OR = 0.915, 95% CI: 0.847–0.987), sexing with regular commercial sexual partners in the past month (OR = 0.892, 95% CI: 0.830–0.959) and having steady non-paying sexual partners (OR = 0.837, 95% CI: 0.752–0.932) among LCFSWs. CMFSWs also reported a decreasing trend of sexing with regular commercial sexual partners in the past month in the study period (OR = 0.375, 95% CI: 0.301–0.467). The difference of Self-reporting of STIs in the last year between LCFSWs and CMFSWs was not statistically significant, but gradually increased among the LCFSWs (OR = 1.052, 95% CI: 1.021–1.084).
Table 2
Behavioural, HIV/AIDS knowledge and prevention services of local Chinese and cross-border migrant FSWs from 2010 to 2018 (%)
Variables
|
2010
N = 1680
|
2011
N = 2366
|
2012
N = 2461
|
2013
N = 3350
|
2014
N = 3197
|
2015
N = 3239
|
2016
N = 1061
|
2017
N = 2185
|
2018
N = 2057
|
All
N = 21596
|
p for χ2
|
p for trend
|
OR (95% CI)
|
Used condoms in the last commercial sex
|
LC
|
91.9
|
91.4
|
96.8
|
95.0
|
98.5
|
98.6
|
98.5
|
98.6
|
98.6
|
96.5
|
0.005
|
< 0.001
|
1.36(1.32–1.42)
|
CM
|
83.3
|
93.9
|
87.7
|
93.5
|
97.0
|
98.5
|
93.8
|
98.0
|
96.3
|
95.2
|
< 0.001
|
1.24(1.12–1.38)
|
All
|
91.7
|
91.5
|
96.3
|
94.9
|
98.3
|
98.6
|
97.8
|
98.5
|
98.3
|
96.4
|
|
< 0.001
|
|
Consistently used condoms in commercial sex last month
|
LC
|
67.2
|
69.4
|
87.1
|
81.3
|
85.7
|
95.0
|
92.3
|
92.3
|
94.4
|
85.1
|
< 0.001
|
< 0.001
|
1.34(1.32–1.37)
|
CM
|
59.5
|
72.7
|
73.9
|
82.6
|
82.8
|
85.1
|
77.0
|
84.3
|
88.8
|
81.7
|
< 0.001
|
1.12(1.06–1.19)
|
All
|
67.0
|
69.5
|
86.4
|
81.4
|
85.4
|
94.2
|
90.1
|
91.2
|
93.8
|
84.9
|
|
< 0.001
|
|
History of illicit drugs use
|
LC
|
2.0
|
0.3
|
0.9
|
1.1
|
1.3
|
0.7
|
1.7
|
1.2
|
2.2
|
1.2
|
< 0.001
|
0.007
|
1.08(1.02–1.13)
|
CM
|
4.8
|
1.5
|
4.6
|
4.0
|
4.1
|
1.2
|
1.1
|
0.3
|
1.4
|
2.3
|
< 0.001
|
0.77(0.67–0.89)
|
All
|
2.1
|
0.3
|
1.1
|
1.4
|
1.6
|
0.7
|
1.6
|
1.1
|
2.1
|
1.3
|
|
0.082
|
|
Self-reporting STIs in the last year
|
LC
|
3.7
|
1.7
|
3.4
|
5.0
|
4.9
|
2.3
|
2.5
|
5.3
|
4.9
|
3.8
|
0.348
|
0.001
|
1.05(1.02–1.08)
|
CM
|
0.0
|
0.0
|
8.5
|
4.7
|
3.0
|
3.8
|
2.2
|
3.3
|
1.4
|
3.3
|
0.097
|
0.90(0.80–1.02)
|
All
|
3.6
|
1.6
|
3.7
|
5.0
|
4.7
|
2.4
|
2.5
|
5.0
|
4.6
|
3.7
|
|
0.008
|
|
Number of male clients in the past month(>60)
|
LC
|
—
|
—
|
—
|
—
|
—
|
—
|
29.2
|
40.7
|
27.2
|
32.9
|
0.066
|
0.021
|
0.92(0.85–0.99)
|
CM
|
—
|
—
|
—
|
—
|
—
|
—
|
23.9
|
33.8
|
29.4
|
29.5
|
0.186
|
1.15(0.94–1.41)
|
All
|
—
|
—
|
—
|
—
|
—
|
—
|
28.4
|
39.8
|
27.5
|
32.4
|
|
0.116
|
|
Sexing with regular commercial sexual partners in the past month
|
LC
|
—
|
—
|
—
|
—
|
—
|
—
|
59.4
|
54.9
|
53.6
|
55.5
|
< 0.001
|
0.002
|
0.89(0.83–0.96)
|
CM
|
—
|
—
|
—
|
—
|
—
|
—
|
87.4
|
61.9
|
46.3
|
65.3
|
< 0.001
|
0.38(0.30–0.47)
|
All
|
—
|
—
|
—
|
—
|
—
|
—
|
63.9
|
55.8
|
52.8
|
56.8
|
|
< 0.001
|
|
Having steady non-paying sexual partners
|
LC
|
—
|
—
|
—
|
—
|
—
|
—
|
16.2
|
11.1
|
11.8
|
12.6
|
< 0.001
|
0.001
|
0.84(0.75–0.93)
|
CM
|
—
|
—
|
—
|
—
|
—
|
—
|
4.8
|
3.0
|
6.5
|
4.6
|
0.398
|
1.21(0.78–1.90)
|
All
|
—
|
—
|
—
|
—
|
—
|
—
|
14.4
|
10.0
|
11.2
|
11.6
|
|
0.011
|
|
Age of male clients ≥ 50 years old
|
LC
|
—
|
—
|
—
|
—
|
—
|
—
|
27.1
|
19.4
|
24.6
|
23.2
|
0.176
|
0.350
|
0.96(0.88–1.05)
|
CM
|
—
|
—
|
—
|
—
|
—
|
—
|
18.7
|
19.1
|
26.2
|
21.0
|
0.057
|
1.25(0.99–1.57)
|
All
|
—
|
—
|
—
|
—
|
—
|
—
|
25.8
|
19.3
|
24.8
|
22.9
|
|
0.900
|
|
Sexing with commercial male clients who used aphrodisiac drugs
|
LC
|
—
|
—
|
—
|
—
|
—
|
—
|
8.3
|
9.3
|
7.0
|
8.2
|
0.042
|
0.114
|
0.90(0.79–1.03)
|
CM
|
—
|
—
|
—
|
—
|
—
|
—
|
8.3
|
5.4
|
4.7
|
6.1
|
0.112
|
0.72(0.49–1.08)
|
All
|
—
|
—
|
—
|
—
|
—
|
—
|
8.3
|
8.8
|
6.8
|
7.9
|
|
0.061
|
|
Accurate HIV-/AIDS-related knowledge
|
LC
|
86.5
|
86.9
|
94.6
|
94.2
|
94.6
|
96.1
|
96.0
|
97.8
|
95.1
|
93.7
|
< 0.001
|
< 0.001
|
1.24(1.21–1.27)
|
CM
|
78.6
|
75.8
|
90.8
|
90.9
|
85.8
|
92.0
|
78.5
|
90.3
|
84.6
|
86.8
|
0.871
|
0.99(0.93–1.06)
|
All
|
86.3
|
86.6
|
94.4
|
93.9
|
93.8
|
95.8
|
93.4
|
96.8
|
94.0
|
93.1
|
|
< 0.001
|
|
Receiving free condom distribution programme last year
|
LC
|
98.7
|
91.1
|
94.9
|
96.5
|
95.2
|
97.2
|
97.2
|
98.9
|
96.6
|
96.1
|
< 0.001
|
< 0.001
|
1.12(1.08–1.15)
|
CM
|
97.6
|
92.9
|
95.4
|
89.5
|
86.5
|
90.1
|
80.9
|
97.3
|
87.8
|
89.6
|
0.351
|
0.97(0.90–1.04)
|
All
|
98.6
|
91.1
|
94.9
|
95.9
|
94.4
|
96.6
|
94.9
|
98.7
|
95.7
|
95.6
|
|
< 0.001
|
|
Receiving methadone maintenance therapy or needle exchange programme last year
|
LC
|
1.8
|
0.3
|
1.2
|
1.0
|
0.5
|
0.4
|
0.9
|
3.1
|
1.0
|
1.0
|
0.028
|
0.013
|
1.08(1.02–1.14)
|
CM
|
4.8
|
0.0
|
4.6
|
4.0
|
2.4
|
0.4
|
0.4
|
0.3
|
0.0
|
1.6
|
< 0.001
|
0.66(0.55–0.79)
|
All
|
1.9
|
0.3
|
1.3
|
1.2
|
0.7
|
0.4
|
0.9
|
2.7
|
0.9
|
1.1
|
|
0.248
|
|
Receiving peer education programme last year
|
LC
|
38.9
|
39.9
|
28.8
|
44.5
|
37.3
|
39.9
|
34.9
|
51.6
|
44.5
|
40.0
|
< 0.001
|
< 0.001
|
1.05(1.04–1.06)
|
CM
|
52.4
|
57.1
|
34.6
|
59.6
|
18.2
|
53.4
|
50.4
|
65.9
|
46.0
|
48.2
|
0.001
|
1.08(1.03–1.13)
|
All
|
39.2
|
40.4
|
29.1
|
45.8
|
35.5
|
41.0
|
37.1
|
53.6
|
44.7
|
40.7
|
|
< 0.001
|
|
Abbreviations: STIs, Sexually Transmitted Infections; LC, local Chinese; CM, cross-border migrant; FSWs, female sex workers; OR, odds ratio; CI, confidence interval.
|
HIV-/AIDS-related knowledge and intervention services
As shown in Table 2, during the nine-year period, the awareness rate of HIV/AIDS-related knowledge among LCFSWs was statistically higher than that of CMFSWs (93.71% versus 86.76%, p < 0.001), with an increasing trend among LCFSWs (OR = 1.239, 95% CI: 1.208–1.272), while there was no significant change among CMFSWs. A higher proportion of receiving free condom distribution programme could be found among LCFSWs than CMFSWs (96.12% versus 89.61%, p < 0.001). However, CMFSWs were more likely to receive methadone maintenance therapy or needle exchange and peer education programmes. There was a significant increase in the utilization of free condom distribution (OR = 1.116, 95% CI: 1.082–1.151), methadone maintenance therapy or needle exchange programmes (OR = 1.076, 95% CI: 1.015–1.140) and peer education programmes (OR = 1.048, 95% CI: 1.036–1.061) among LCFSWs. Increasing trend was also found in peer education programme (OR = 1.078, 95% CI: 1.031–1.127) among CMFSWs, however, the trend of receiving methadone maintenance therapy or needle exchange programme among CMFSWs was decreased (OR = 0.657, 95% CI:0.546–0.790).
Risk factors associated with HIV-1 infection
From 2010 to 2015, as shown in Fig. 2, there were two common risk factors for HIV-1 infection among both LCFSWs and CMFSWs: staying in current residence > 12 months and self-reporting STIs in the last year. Beyond that, receiveing less than 6 years of education background (OR = 3.731, 95% CI: 1.143–12.185), illicit drugs use (OR = 12.398, 95% CI: 6.555–23.449),staying in current residence for more than 12 months (OR = 1.788, 95% CI: 1.165–2.744), and inconsistant condom use in the last month (OR = 1.595, 95% CI: 1.045–2.436) were significantly associated with HIV-1 infection among LCFSWs. For CMFSWs, the unique factor for HIV-1 infection was age > 35 years old ( OR = 2.428, 95%CI: 1.096–5.381). However, LCFSWs had lower odds to be HIV-1 infected if they had been staying in current residence for 6 ~ 12 months (OR = 0.397, 95% CI: 0.166–0.952).
From 2016 to 2018, self-reporting STIs in the last year was the shared factor significantly related to HIV infection across both groups. For CMFSWs, self-reporting of STIs in the last year (OR = 25.936, 95% CI: 4.336-155.138),and inconsistent condoms use in commercial sex in the last month (OR = 3.527, 95% CI: 1.153–10.784) were significantly associated with HIV-1 infection, while receiving peer education programme in the past year (OR = 0.204, 95% CI: 0.057–0.732) presented a protective effect for HIV-1 infection. Regarding to LCFSWs, self-reporting STIs in the last year (OR = 4.044, 95% CI: 1.558–10.498) and engaging in commercial sex with male clients who used aphrodisiac drugs (OR = 4.029, 95% CI: 1.709–9.497) were significantly associated factors for HIV-1 infection.
Risk factors associated with syphilis infection
From 2010 to 2015, as shown in Fig. 2, staying in current residence for more than 12 months, self-reporting of STIs in the last year and illicit drug use were the shared significant factors to syphilis infection among both LCFSWs and CMFSWs. In addition, inconsistent condoms use in commercial sex in the past month (OR = 2.506, 95% CI: 1.235–5.086) was significant risk factor for syphilis infection among CMFSWs, while low-tier working venues (OR = 1.882, 95% CI: 1.275–2.779), age > 35 years old (OR = 1.547, 95% CI: 1.296–1.846), and receiving less than 6 or 9 years of education (less than 6 years: OR = 2.387, 95% CI: 1.538–3.705; less than 9 years: OR = 1.737, 95% CI: 1.30–2.670) were risk factors for syphilis infection among LCFSWs. The marital status of unmarried/divorced/widowed (OR = 0.835, 95% CI: 0.698–0.998) presented a protective effect for syphilis infection among LCFSWs.
During 2016–2018 period, low-tier working venues, engaging in commercial sex with male clients who used aphrodisiac drugs and self-reporting of STIs in the last year were related to syphilis infection among both LCFSWs and CMFSWs. Regarding to LCFSWs, experience as FSW for more than 5 years (OR = 1.478, 95% CI: 1.119–1.951), receiving less than 6 years of education (OR = 1.927, 95%CI: 1.008–3.681) and history of illicit drug use (OR = 2.619, 95% CI: 1.084–6.33) were associated with syphilis infection.