Lau, Joseph T. F. PhD*; Zhang, Linglin MD†; Zhang, Yun MBA‡; Wang, Ning PhD§; Lau, Mason MSc*; Tsui, Hi-Yi MPhil*; Zhang, Jianxin MSc∥; Cheng, Feng PhD¶
AS OF DECEMBER 2005, it is officially estimated that there were approximately 0.65 million people living with human immunodeficiency virus (HIV) or acquired immune deficiency syndrome (AIDS) in China.1 International organizations have joined forces with the Chinese workers to promote HIV-related prevention and care in China,2 and evaluation of these efforts is greatly warranted. Evaluation of the overall effectiveness of programs targeting HIV harm reduction among injecting drug users (IDU) at the community level have been reported in a number of countries3–5 One of the functions of Behavioral Surveillance Surveys (BSS) is that it can be used to assess the overall effectiveness of programming efforts at the community level,6 by conducting regular, serial, and cross-sectional surveys using similar methodologies.7 Such surveys have been implemented in a number of countries, such as the United States, Thailand, Vietnam, Indonesia, and Nigeria.8–12
The China-UK HIV/AIDS Prevention and Care Project supported the development of BSS in the Sichuan and Yunnan provinces.13 Both funding and technical support have been provided by United Kingdom’s Department for International Development and Family Health International (FHI). The first round of BSS was implemented in 2002, with 8 sites in Sichuan and 3 sites in Yunnan; the number of surveillance sites then increased to 21 and 11 respectively in 2003 and 2004, and 21 and 24 respectively in 2005, covering HIV vulnerable groups such as IDU, female sex workers (FSW), and long-distance truck drivers.
There is a consensus that HIV transmission among IDU has been the driving force of the China HIV epidemic14 as well as in some other Asian cities.15 As of December 2005, IDU comprised 39.3% of the total number of reported HIV cases in China.16 In some studies, the HIV prevalence among IDU in different parts of China ranged from 11% to 70%17–19 and increasing trends in HIV prevalence have also been reported.20 The national sentinel data for HIV prevalence in this group is about 6% to 8%.21
In 2005, Sichuan ranked the sixth among all Chinese provinces in the number of reported HIV cases.16 A number of surveillance sites in Sichuan show that the HIV prevalence among IDU ranged from 0% to 66.0% in year 2003.22 The sheer population size of Sichuan (87.3 million at the end of 2004,23) makes it a strategic focus of HIV prevention in China. Since 2003, the China-UK Project has implemented various intervention programs (e.g., expanded comprehensive integrated response) in a number of cities in Sichuan. Such programs combined BSS with interventions such as needle exchange, peer education, outreach intervention, condom distribution, voluntary counseling and testing, seminars and support group for stakeholders, and sexually transmitted diseases (STD) services.24 In particular, various harm reduction services were set up in these intervention sites during the study period. Outreach services were provided to IDU in all sites by trained medical and health workers. The outreached clients received information and training about HIV prevention, including HIV/STD-related knowledge, needle cleaning techniques, condom promotion, etc. Through these outreach services, IDU were also invited to use free voluntary HIV testing and counseling services, which were conducted by trained professionals at clinics of the local Centre for Disease Control and Prevention (CDC) and other centers. In all sites, needle exchange programs were implemented. Peer workers were trained and exchanged free new syringes with used ones from the IDU. Needle exchange centers were established in the neighborhood for the purpose. Methadone maintenance treatment clinics were also established during the study period in all these sites. Under medical supervision, users were given methadone on a daily basis at a cost of 10 RMB (about 1.5 US $). In addition, other services targeting FSW (e.g., peer education, seminars, condom distribution, and STD-related services) also covered some of the female IDU who were engaged in sex work. These services were standardized and monitored by the China-UK Project and were implemented on a large-scale.
Using BSS data collected in Sichuan, this study described and compared both baseline values as well as changes in the various evaluative indicators of overall HIV-related prevention program effectiveness at the community level. These parameters included HIV-related knowledge and perceptions, IDU-related and sex-related risk behaviors, and utilization of HIV-related preventive services.
The methodology of the BSS in Sichuan has been documented in detail in a China-UK project report.25 Other articles using database of the China-UK Project have been published26–28 Supported by international and national experts, a series of meetings were held in 2002 to translate and to modify the BSS questionnaires developed by the FHI. Intensive training sessions (a 3-day workshop) were provided to interviewers by experienced researchers from the School of Public Health of Sichuan University and staff of national and provincial CDC. Local CDC core staff also attended training workshops organized by the China-UK Project. A detailed operational manual was prepared and used. Interviewers kept a log book describing their fieldwork and were supervised by senior local CDC staff who performed field and office editing. Data collection was also monitored by the provincial and national level experts. An independent international monitoring team was sent to some of the sites to review the documentation and quality of the fieldwork. The team also visited some establishments and interviewed some respondents and was satisfied with the quality of the study.
Since a sampling frame of noninstitutionalized IDU does not exist, community-based snowball method was used for recruitment of respondents. Informants connected outreach workers with IDU and other stakeholders, who further introduced more prospective respondents to the field workers. Face-to-face interviews, using a structured questionnaire, were implemented in settings where privacy was ensured. Pilot tests were conducted before the implementation of the actual fieldwork. Trained field workers who were medical staff of the local CDC explained the purposes of the study to prospective respondents. Respondents were assured that participation was absolutely voluntary, anonymous, and confidential. Verbal informed consent was obtained and the field worker signed a form pledging that he/she had explained the information clearly to the respondents. Ethics approval was obtained from the national CDC in China. A cash incentive of RMB 50 (about US $6) was given to the participant to compensate for their time.
During 2002–2004, 6 cities in Sichuan had implemented BSS and ECIR on the IDU population (In 2002, 2003, and 2004, there were 3, 5, and 6 BSS sites for IDU in Sichuan.). One of these sites only had 1 round of survey by 2004 and no comparison could be made against baseline data. Data obtained from BSS for IDU in the other 5 sites in Sichuan were hence used for this study.
Information collected included background characteristics (sociodemographic characteristics, HIV-related knowledge and perception, having taken voluntary HIV antibody testing, and ever having attempted to quit drugs voluntarily), syringe-sharing behaviors (injecting with others’ used syringes in the last episode/last month/last six months, providing one’s used syringes to others for drug injection in the last month, injecting drugs from prefilled syringes in the last month), syringe-rinsing behaviors in the last month among those who shared syringes as well as whether having different types of sex partners (commercial sex partners in the last month, currently having regular or nonregular sex partners), and prevalence of unprotected sex in the last episode of sex with different types of sex partners. Questions about utilization of various HIV-related preventive services were asked in some of the surveys (Table 1).
The distributions of the respondents’ background characteristics, prevalence of IDU-related risk behaviors and sex-related risk behaviors that were measured in the baseline surveys were tabulated by respective sites. Similar prevalence data obtained from surveys conducted in 2003 (which were the second round of BSS for sites 1, 2, and 3) and in 2004 (which were the third round of BSS for sites 1, 2, and 3, and the second round for sites 4 and 5) were also tabulated and were compared with the respective baseline data by multivariate odds ratios (OR), derived from multivariate logistic regression models adjusting for age group, gender, education level, ethnicity, and duration of injecting drug use. For sex-related risk variables, the above analyses were further stratified by gender. Baseline results are summarized in Tables 1 and 2 while comparisons with baseline data are summarized in Tables 3–5. SPSS 13.0 for Window was used for data analysis; P <0.05 was considered statistically significant.
Background Characteristics at the Time of Baseline Surveys
Results are summarized in Table 1. It can be seen that the baseline surveys for sites 1, 2, and 3 were conducted in 2002 and those for the other 2 sites were conducted in 2003. The percentages of females ranged from 21.8% to 32.1%; the majority of the respondents were Han (except for site 3); 68.2% to 92.2% of the respondents were below 35-years-old and only 14.6% to 25.3% of the respondents had an education level of senior high school or above. Of the respondents in the various sites, 26.9% to 56.0% had injected drug for 3 or more years; 4.1% to 20.0% had received an HIV antibody test, and 10.2% to 89.8% had ever attempted to quit drug use. Furthermore, 37.3% to 80% gave appropriate answers to at least 4 out of 5 HIV-related knowledge items; 59.6% to 91% and 73.8% to 89%, respectively believed that condom use and avoidance of sharing needles could prevent HIV. There was no baseline data on utilization of HIV preventive services for sites 1 to 3 (such questions were not asked in 2002), while prevalence of exposure to HIV-related services at the baseline survey (2003) for sites 4 and 5 were very low (Table 1).
IDU-Related Behaviors at the Baseline
The results are summarized in Table 2. Of all respondents, 24.7% to 54.1% injected with others’ used syringes in the last month (5.8%–32.3% of all respondents did so in the last episode of injecting drug use); 11.7% to 21% injected drugs from prefilled syringes in the last month; 25.3% to 52.2% provided others with their used syringes for drug injection in the last month; 41.9% to 65.2% had practiced one of the 3 behaviors (using others’ syringes, provided others with used syringes for drug injection, or injected drugs from prefilled syringes). Among those who shared syringes in the last month, 17.9% to 64.8% had rinsed the syringes with cool water; 37.1% to 66.9% had cleansed the syringes with hot water or steam, and 2.3% to 8.8% rinsed them with alcohol or bleaching agent.
Prevalence of Different Types of Sex Partnerships at the Baseline
Of all male respondents, 6.8% to 36.1% from various sites were engaged in commercial sex in the last month. Corresponding figures for all female respondents ranged from 19.8% to 46.2%. Moreover, 19.3% to 58% of all male respondents and 23.1% to 39.3% of all female respondents reported current nonregular sex partnerships. Corresponding figures for current regular sex partnership were 25% to 62.1% for males and 45.3% to 74.5% for females, respectively (Table 2).
Condom Use Behaviors at the Baseline
The results of Table 2 suggest that of respondents who reported having regular sex partners, 76.4% to 88.3% of males and 80.4% to 92.2% of females had engaged in unprotected sex in their last episode of sex with their regular sex partners. Corresponding figures for unprotected sex with nonregular sex partners among those with nonregular sex partners were 74.4% to 88.3% for male respondents and 55.8% to 79.4% for female respondents. Among respondents who engaged in commercial sex in the last month, the corresponding prevalence of unprotected sex with commercial sex partners were 73.9% to 91.5% for male respondents and 44.4% to 70.6% for female respondents (5.4%–28.2% for all sampled male respondents and 8.8%–25.3% for all sampled female respondents).
Comparison of HIV-Related Knowledge and Perceptions and HIV-Related Preventive Services Utilization Measured in 2003 and 2004 With Their Respective Baseline Measures
For sites 1 to 3, data obtained from the 2003 and 2004 surveys were compared with their 2002 baseline measures while 2004 survey data for sites 4 and 5 were compared with 2003 baseline data (Table 3). In most of such follow-up surveys, the majority of the respondents of the 2nd and 3rd round BSS surveys correctly answered at least 4 of the 5 HIV-related knowledge items. The OR comparing these figures to their respective baseline data (listed in Table 1), showed highly significant improvement for most of the cases [OR = 1.6, 95% confidence interval (CI): 1.0–2.5 to OR = 213.8, 95% CI: 69.0–721.2, P <0.05, Table 3] except one (OR = 0.4, 95% CI: 0.3–0.6, Table 3).
Baseline data for HIV-related preventive services had not been collected in 2002 for all sites. A comparison of data obtained in 2004 for sites 1, 2, 3, and 4 with their 2003 baseline measures, generally revealed better coverage for various types of programs for sites 1, 2, and 4 but not site 3 (Table 3). In 2004, 36.5% to 75% of the respondents had used at least 1 type of the listed HIV prevention services (Table 3).
Comparison of Prevalence of IDU-Related Behaviors Measured in 2003 and 2004 With Their Respective Baseline Measures
The results are summarized in Table 4. When data obtained from sites 1 to 5 in 2004 were compared with their respective baseline data, improvements in most of the parameters related to IDU-related behaviors were of statistical significance. The improvements seemed more apparent in sites 2, 3, 4, and 5 as compared to site 1. In 2004, the prevalence of using others’ syringes in the last month (ranging from 11%–18.9%) decreased for sites 2, 3, 4, and 5, as compared to their baseline measures (ranging from 24.7%–54.1%, OR = 0.1, 95% CI: 0.09–0.2 to OR = 0.6, 95% CI: 0.4–0.9, P <0.05). About the 2003 data, improvements were also seen for most parameters for sites 2 and 3, whereas increase in IDU-related risk behaviors was seen for site 1, in comparison with the 2002 baseline data.
Among those who shared syringes in site 3 (2003) and site 5 (2004), more respondents as compared to the respective baselines cleansed the used syringes with bleaching agent or alcohol before using them for drug injection (OR = 4.4, 95% CI: 2.0–9.4 and OR = 5.9, 95% CI: 1.0–27.6, respectively). In 2004, percentages among syringe-sharers who rinsed syringes with alcohol or bleaching agent were still quite low (0%–1.1%). In 2004, fewer respondents as compared to the baselines, used cool water to rinse their syringes in sites 2 and 3 (OR = 0.5, 95% CI: 0.3–0.9 and OR = 0.2, 95% CI: 0.09–0.4, respectively).
Comparison of Prevalence of Condom Use Measured in 2003 and 2004 With Their Respective Baseline Measures
The results are summarized in Table 5. It can be seen that significant improvements in prevalence of condom use were observed in sites 2, 3, and 5 (OR = 0.05, 95% CI: 0.01–0.2 to OR = 0.4, 95% CI: 0.2–0.9) but not in sites 1 and 4, when parameters related to condom use with nonregular sex partner (NRP) or commercial sex partners measured in 2004 were compared with their respective baselines. Improvement of condom use with regular sex partners was however, much less evident when similar comparisons between 2004 and baseline data were made. Yet, the prevalence of unprotected sex with commercial sex partners or NRP remained high, even for sites 2, 3, and 5 where substantial improvements were documented. For instance, 68.8% to 79.1% of the male respondents in these 3 sites in 2004 who were having a NRP did not use a condom in the last episode of sex with such NRP (as compared to baseline data of 83.0%–88.3%). Corresponding figures for prevalence of unprotected sex with the last commercial sex partner in these 3 sites ranged from 65.2% to 75.0% in 2004 (vs. 73.9%–91.5% in the baseline surveys). Improvements were observed for sites 1 and 3 but not for site 2 in the 2003 data.
Comparison of Prevalence of Engagement in Sex Partnerships Measured in 2003 and 2004 With Their Respective Baseline Measures
The results are summarized in Table 5. In 2004, the prevalence of engaging in commercial sex in the last month among male respondents ranged from 3.9% to 15.3% (as compared to 6.8%–36.1% in the baseline surveys, Table 2). Significant decreases were observed for sites 2, 3, and 5. Corresponding prevalence in 2004 for female respondents ranged from 10% to 82.9%. A sharp increase was recorded in site 1 (as compared to 19.8%–46.2% in respective baseline surveys; see Table 2) and significant decrease was seen in site 5 (OR = 0.3, 95% CI: 0.2–0.5). Similar decrease in prevalence in 2004 for having regular and nonregular partners was observed in some sites, as compared to respective baseline data (Table 5).
Data on coverage rates of HIV-related services were not collected in 2002 and were only collected for Sites 4 and 5 in 2003, which reported very low figures. However, noteworthy proportions of the respondents had been covered by various HIV prevention programs in 2004. Therefore, baseline data used in this study (collected in 2002 and 2003) serve as appropriate references for evaluating overall program effectiveness for various intervention programs which were launched in between the implementation of the baseline surveys and the 2nd and 3rd rounds of BSS in the studied sites.
In the baseline surveys, about 40% either injected with others’ used syringes or provided used syringes to others for injection. Given the very high HIV prevalence among IDU in some of these places (e.g., in site 1: 65.1% in 2003, personal communication with the site’s local CDC director), large numbers of HIV transmission could have been resulted via IDU-related behaviors. These HIV infections accumulated before being detected and hence, even in the presence of effective programs, it takes a few years before the HIV prevalence would become stabilized. Effective programs are therefore urgently warranted and public health workers are competing with time.
Coverage rate is another important issue. High coverage is required not only within the studied sites but also across the entire province. Quick assessments should be made for places where prevalence of IDU seems high and immediate actions should be taken. It should be noted that HIV prevalence among IDU in some provinces is over 20% (e.g., Guangxi province),29 some coordinated national efforts are warranted. Without dramatic changes, IDU may continue to be the driving force of the HIV epidemic in China for the years to come.
The important message of this report is that HIV prevention programs in China are quite effective and that there were considerable improvements at the community level even within a short time frame of 1 to 2 years. Obvious improvements were seen for prevalence of injecting with others’ used syringes, injecting drugs from prefilled syringes, and providing one’s used syringes to others. Although such improvements were not observed in some particular cases, the trend for improvement in harm reduction has been clear and consistent. It should however be borne in mind that the rule of diminishing return may apply to this case of harm reduction and that the rate of improvement over time in the future may not be linear.
The efficiency of the spread of HIV from the IDU population to other populations (e.g., the FSW population) is one of the most important determinants of future HIV prevalence in China.30 HIV is being transmitted from the male IDU and female IDU to their various types of sex partners30–32 This study shows that the situation is of great concern as the prevalence of unprotected sex among male and female IDU with their commercial, regular, and nonregular sex partners had been extremely high in the baseline surveys (close to or above 80% in many cases). When the 2004 data were compared with their baseline data, it is encouraging that statistically significant improvements in condom use have been observed for both male and female IDU when having sex with commercial or nonregular sex partners in 3 of the 5 sites. Yet, the prevalence for unprotected sex in 2004 remained very high. Moreover, such improvements were not observed for regular sex partners for all 5 sites. Enhanced services for promoting condom use are greatly warranted for IDU in Sichuan, China.
Given the high prevalence of HIV in these IDU populations, the bridging pathways for HIV transmission from IDU populations to their sex partners are therefore still wide open. Integration of sex and IDU harm reduction are most essential. Biologic and behavioral surveillance for these IDU groups involving in commercial sex activities should also be strengthened and be treated as a separate entity in BSS.
Significant improvements were documented for HIV-related knowledge and perceptions in 4 of the 5 sites. The relationships between HIV-related knowledge and IDU-related or sex-related risk behaviors in our sample are not to be addressed by this article, which focuses on the evaluative applications of BSS data. In the international literature, relationship between HIV-related perceptions/knowledge and HIV-related risk behaviors have been mixed.33
The study has some limitations. Onsite random sampling was not feasible and convenience sampling methods were used in the venues for recruitment of study participants. Reporting bias due to social desirability may also exist and as such applies to all BSS studies; the interviews were strictly anonymous and privacy was ensured. Interviewers were also trained to encourage respondents to give true answers. IDU respondents tended to have a shorter attention span. The questionnaire took about 10 minutes to complete and conducted thorough pilot testing. It should also be noted that these sites were covered by the China-UK Project, which also implemented intervention programs for FSW and IDU in these sites. Therefore, caution should be made when generalizing the results to other parts of Sichuan. Similar improvements in nonintervened parts of Sichuan are not expected. Besides, overall rather than specific program effectiveness was indicated in this study. Though the China-UK projects played an essential role for HIV intervention activities in these sites, other prevention efforts could contribute to behavioral changes. As the intervention projects of the China-UK Project were coordinated by the provincial and local CDC, and other nongovernmental organization activities were virtually absent, it was known that other prevention programs in these sites were of a very small scale. We may hence conclude that the China-UK Project possibly, though not definitely, contributed to the observed changes. Another limitation is that all sites were intervened and there were no control communities for comparison. Furthermore, BSS data were cross-sectional in nature and hence, associations rather than causal relationships were reported. Relatedly, we could not measure whether behavior changes were sustained. Such information could only be obtained from expensive prospective randomized controlled studies. The surveys were of high quality as they have been conducted with careful planning, training, pilot testing, implementation, documentation, and quality control, as part of an international collaborative project.
In conclusion, HIV transmission among IDU in Sichuan is of concern. The baseline data should be comparable to other places in the province where coverage rate of intervention programs is low and the level of both IDU-related and sex-related risk behaviors is high. The promising side is that if intensity of interventions is to be increased, detectable improvements would be evident within 1 to 2 years. BSS data are therefore important in uncovering the baseline conditions and for evaluating overall intervention program effectiveness at the community level. Such results can further be utilized as feedback to funding agents, programmers, workers, and other stakeholders for policy advocacy purposes. Analyzing BSS data are not straightforward as the number of sites and number of rounds of survey within these sites increase over time but such efforts are very worthwhile. The last but not the least, BSS data analysis should be included as part of the BSS and be well planned.
1. Ministry of Health, People’s Republic of China, UNAIDS, & WHO. 2005 Update on the HIV/AIDS Epidemic and Response in China. National Center for AIDS Prevention and Control, Beijing, China. January 2006.
2. Wu FS. International non-governmental actors in HIV/AIDS prevention in China. Cell Res 2005; 15:919–922.
3. Barrett ME, de Palo MP. Community-based intervention to reduce demand for drugs in Northern Thai tribal villages. Subst Use Misuse 1999; 34:1837–1879.
4. Lin P, Fan ZF, Yang F, et al. Evaluation of a pilot study on needle and syringe exchange program among injecting drug users in a community in Guangdong, China [Chinese] Chinese Journal of Preventive Medicine 2004; 38:305–308.
5. Vazirian M, Nassirimanesh B, Zamani S, et al. Needle and syringe sharing practices of injecting drug users participating in an outreach HIV prevention program in Tehran, Iran: A cross-sectional study. Harm Reduct J 2005; 2:19.
6. Family Health International and UNAIDS. Meeting the Behavioural Data Collection Needs of National HIV/AIDS and STD Programmes. A Joint IMPACT/FHI/UNAIDS Workshop: Report and Conclusions. Arlington, VA: Family Health International, May 1998.
7. Amon J, Brown T, Hogle J, et al. Behavioral Surveillance Surveys BSS: Guidelines for Repeated Behavioral Surveys in Populations at Risk of HIV. Arlington, VA: Family Health International, 2000.
8. Centers for Disease Control and Prevention, United States. National HIV Behavioral Surveillance. Program in Brief. January 2004. Available at: http://www.cdc.gov/programs/hiv10.htm
. Accessed August 28, 2005.
9. Mills S, Benjarattanaporn P, Bennett A, et al. HIV risk behavioral surveillance in Bangkok, Thailand: Sexual behavior trends among eight population groups. AIDS 1997; 11(suppl 1):S43–S51.
10. Tung ND, Tuan NA, Hoang TV, et al. HIV/AIDS Behavioral Surveillance Survey Vietnam 2000 (BSS Round 1 Results). USAID/FHI/Impact/NASB, 2001.
11. Utomo B, Dharmaputra NG, Haryanto B, et al. Indonesia HIV/AIDS behavioral surveillance survey: Results from the Cities of North Jakarta, Surabaya, and Manado. Jakarta: Center for Health Research, 1997.
12. Family Health International. HIV/AIDS Behavioral Surveillance Survey: Nigeria 2000 (Report and Data sheets). Arlington, VA: Family Health International.
14. Wu Z, Rou K, Cui H. The HIV/AIDS epidemic in China: History, current strategies and future challenges. AIDS Educ Prev 2004;16(suppl):7–17.
15. Brown T, Peerapatanapokin W. The Asian Epidemic Model: A Process Model for Exploring HIV Policy and Programme Alternatives in Asia. Sex Transm Infect 2004; 80(Suppl 1):i19–i24.
17. Ruan Y, Chen K, Hong K, et al. Community-based survey of HIV transmission modes among intravenous drug users in Sichuan, China. Sex Transm Dis 2004; 31:623–627.
18. Zhang C, Yang R, Xia X, et al. High prevalence of HIV-1 and hepatitis C virus coinfection among injection drug users in the southeastern region of Yunnan, China. J Acquir Immune Defic Syndr 2002; 29:191–196.
19. Zhang G, Zheng X, Liu W, et al The survey of HIV prevalence among drug users in Guangxi, China. [Chinese] Chinese Journal of Epidemiology 21:15–16, 2000.
20. Qian ZH, Vermund SH, Wang N. Risk of HIV/AIDS in China: Subpopulations of special importance. Sex Transm Infect 2005; 81:442–447.
22. China-UK HIV/AIDS Prevention and Care Project in Sichuan. Comprehensive Surveillance Report for HIV/AIDS, Sichuan 2003. Sichuan China-UK HIV/AIDS Prevention and Care Project Office. June 2004.
23. National Bureau of Statistics of China. China Statistical Yearbook 2005. Beijing: China Statistics Press, 2005.
25. China-UK HIV/AIDS Prevention and Care Project in Sichuan. Behavioral Surveillance Report for HIV/AIDS, Sichuan 2002. Sichuan China-UK HIV/AIDS Prevention and Care Project Office. March 2003.
26. Lau JTF, Wang R, Chen H, et al. Evaluation of the overall program effectiveness of HIV-related intervention programs in a community in Sichuan, China. Sex Transm Dis (In press).
27. Lau JTF, Cheng F, Tsui HY, et al. Clustering of syringe sharing and unprotected sex risk behaviors in male injecting drug users in China. Sex Transm Dis (In press).
28. Lau JTF, Zhang J, Zhang L, et al. Comparing prevalence of condom use among 15379 female sex workers injecting or not injecting drugs in China. Sex Transm Dis (In press).
29. State Council AIDS Working Committee Office and UN Theme Group on HIV/AIDS in China. A Joint Assessment of HIV/AIDS Prevention, Treatment and Care in China (2004). Beijing, China. December 2004.
30. Liu H, Grusky O, Li X, et al. Drug users: A potentially important bridge population in the transmission of sexually transmitted diseases, including AIDS, in China. Sex Transm Dis 2006; 33:111–117.
31. Choi SY, Cheung YW, Chen K. Gender and HIV risk behavior among intravenous drug users in Sichuan Province, China. Soc Sci Med 2006; 62:1672–1684.
32. Lau JT, Feng T, Lin X, et al. Needle sharing and sex-related risk behaviours among drug users in Shenzhen, a city in Guangdong, southern China. AIDS Care 2005; 17:166–181.
33. Fisher JD, Fisher WA. Theoretical approaches to individual-level change in HIV risk behavior. In: Peterson JL, DiClemente RJ, eds., Handbook of HIV Prevention. New York: Kluwer Academic/Plenum, 2000;3–55.