Ruan Y, Liang S, Zhu J, Li X, Pan SW, Liu Q, Song B, Wang Q, Xing H, Shao Y. Evaluation of harm reduction programs on seroincidence of HIV, hepatitis B and C, and syphilis among intravenous drug users in southwest China. Sex Transm Dis. 2013 Apr;40(4):323-328.
To evaluate the impact of a multifaceted harm reduction program among intravenous drug users (IDU), before and after implementation of the program.
Xichang city, Sichuan province, southwest China.
Prospective double cohort study evaluating the impact of a structural intervention.
IDU ≥18 years of age, HIV-seronegative at baseline, who had injected drugs at least once in the preceding three months.
Seroincidence of HIV, HBV, HCV and syphilis.
Xichang implemented a multi-component harm reduction program in 2004, which included methadone maintenance therapy (MMT), needle-exchange, addiction counseling, and condom promotion. Participants were enrolled in two prospective cohorts (cohort 2002-2004 and cohort 2006-2008). Participants in cohort 2002-2004 represented Xichang's pre-intervention IDU population and cohort 2006-2008 represented the city's post-intervention IDU population.
Participants were recruited through community-based outreach and snowball sampling, and were asked to return to the study clinic for follow-up evaluations every six months for up to 24 months. Interviewers collected demographic data as well as data concerning drug injection practices and sexual risk behavior. Every six months, blood samples were collected from participants to test for HIV, HBV, HCV and syphilis. HIV infection status was determined by an enzyme immunoassay (EIA) with Western blot confirmation. HBV and HCV infection status were determined by EIA tests for antigens and antibodies, respectively. Syphilis infection was determined using an EIA and confirmed using a particle agglutination test.
Univariate proportions and means respectively were calculated for categorical and continuous variables. To assess differences between the 2002-2004 and 2006-2008 cohorts at baseline, χ2 tests and t tests respectively were used for categorical and continuous variables. Investigators calculated incidence based on Poisson distributions and as cases per 100 person-years (PY) of follow up. Investigators estimated seroconversion dates by using the midpoint between the last negative and the first positive antibody test result. They used multivariate Poisson regression models to compare seroincidence rates of HIV, HCV, HBV, and syphilis for 24 months of follow-up in cohort 2002-2004 as well as in cohort 2006-2008. Investigators also performed a separate 12-month subgroup analysis restricted to the years 2002-2003, as some participants in cohort 2002-2004 had accessed MMT soon after it was offered in 2004.
A total of 333 HIV-seronegative eligible IDUs were recruited into cohort 2002-2004, and 376 were recruited into cohort 2006-2008. Follow-up retention rates at 12 and 24 months were 70.3% and 75.7% respectively for cohort 2002-2004, and 89.4% and 83.8% respectively for cohort 2006-2008. There were some demographic and behavioral differences between the cohorts. Cohort 2002-2004 participants were significantly younger, had less education, had lower incomes and were more likely to be members of an ethnic minority than their counterparts in cohort 2006-2008. They were also more likely to have used heroin and shared needles in the preceding three months. However, there were no significant differences between the cohorts with regard to gender, employment status, marital status, home- or apartment-ownership or reported sexual risk behavior.
HIV seroincidence was significantly lower in cohort 2006-2008 than it was in cohort 2002-2004. In 642.6 PY of observation, four HIV seroconversions were observed in cohort 2006-2008, while 12 were observed in 473.5 PY in cohort 2002-2004. HIV incidence was thus 0.6 per 100 PY (95% confidence interval [CI] 0.01 to 1.2) in cohort 2006-2008, and 2.5 per 100 PY (95% CI 1.1 to 4.0) in cohort 2002-2004. The rate ratio (RR) between the cohorts was 4.27 (95% CI 1.22 to 14.92). In the subgroup analysis of the pre-MMT 12-month period in 2002-2003, there were eight HIV seroconversions in 252 PY, corresponding to an incidence of 3.2 per 100 PY (95% CI 1.0 to 5.4). The RR of HIV seroconversions between cohort 2006-2008 and the 2002-2003 subgroup was 4.96 (95% CI 4.30 to 18.95).
Baseline prevalence of HCV was high in both cohorts, 67.9% and 69.7% respectively. Seroincidence of HBV, HCV and syphilis were lower in cohort 2006-2008 than they were in cohort 2002-2004, but the differences were not significant. HBV incidence in cohort 2006-2008 was 8.8 per 100 PY (95% CI 6.3 to 11.3) compared to 12.0 per 100 PY (95% CI 8.4 to 15.6) in cohort 2002-2004 (RR 1.42, 95% CI 0.91 to 2.22). HCV incidence in cohort 2006-2008 was 30.3 per 100 PY (95% CI 21.2 to 39.4) compared to 38.5 per 100 PY (95% CI 26.8 to 50.1) in cohort 2002-2004 (RR 1.21, 95% CI 0.76 to 1.91. Syphilis incidence in cohort 2006-2008 was 4.1 per 100 PY (95% CI 2.4 to 5.8) compared to 4.7 per 100 PY (95% CI 2.6 to 6.8) in cohort 2002-2004 (RR 1.17, 95% CI 0.61 to 2.25).
In the subgroup analysis of the pre-MMT 12 months in 2002-2003, there was a significant difference in HBV incidence compared to cohort 2006-2008. HBV incidence in 2002-2003 was 14.2 per 100 PY (95% CI 8.9 to 19.4; RR 1.67, 95% CI 1.01 to 2.76). Although incidence declined, differences were not significant for HCV (RR 1.33, 95% CI 0.79 to 2.24) or syphilis (RR 1.39, 95% CI 0.67 to 2.89).
The authors conclude that harm reduction strategies may be an effective means of reducing the spread of HIV, HBV, HCV and syphilis among high-risk IDUs in southwest China. They found, however, that most study participants were unaware of, unwilling to use, or unable to access harm reduction services.
The risk of bias in this study is moderate to high. Although two cohorts were compared, there were important differences between them that may have resulted in an overestimation of the intervention's effects. Sample sizes were also fairly small, and the study may have been insufficiently powered to detect changes in HCV, which was already highly prevalent, or syphilis incidence. The authors point out other study limitations that may have led to bias, including low uptake of the intervention, temporal changes in regard to drug access and HIV knowledge, possible exposure misclassification bias in cohort 2002-2004, and a possible over-reliance on treponemal diagnostic tests for syphilis.
The HIV epidemic in southern China has largely been fueled by IDU.(1, 2) Xichang has a population of >600,000, with many thousands of incoming migrants each year. The city has about 2,500 registered IDU. The region is a part of the "Golden Triangle," a major international opium-growing area, and has China's highest HIV prevalence (>20% prevalence in IDU).(3, 4, 5) China began implementing harm reduction programs at the national and local levels in 2004, some of which, like this one, are multifaceted.(6, 7, 8, 9, 9)
Although legality, cultural contexts, resource availability and other factors will vary widely, national and sub-national programs may consider piloting a similarly comprehensive package of harm reduction interventions for IDU.
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