The impact of sex partners' HIV status on HIV seroconversion in a prospective cohort of injection drug users

HIV treatment as prevention among people who inject drugs - a re-evaluation of the evidence

Background

Population-level associations between community measures of HIV viral load and HIV incidence have been interpreted as evidence for HIV anti-retroviral treatment (ART) as prevention among people who inject drugs (PWID). However, investigation of concurrent HCV and HIV incidence trends allows examination of alternative explanations for the fall in HIV incidence. We estimate the contribution of ART and reductions in injecting risk for reducing HIV incidence in Vancouver between 1996 and 2007.

Methods

A deterministic model of HIV and HCV transmission among PWID was calibrated to the baseline (1996) HIV and HCV epidemic among PWID in Vancouver. While incorporating parameter uncertainty, the model projected what levels of ART protection and decreases in injecting risk could reproduce the observed reduction in HIV and HCV incidence for 1996-2007, and so what impact would have been achieved with just ART or just reductions in injecting risk.

Results

Model predictions suggest the estimated reduction (84%) in HCV incidence for 1996-2007 required a 59% (2.5-97.5 percentile range 49-76%) reduction in injecting risk, which accounted for nine-tenths of the observed decrease in HIV incidence; the remainder was achieved with a moderate ART efficacy for reducing sexual HIV infectivity (70%, 51-89%) and an uncertain ART efficacy for reducing injection-related HIV infectivity (44%, 0-96%). Despite this uncertainty, projections suggest that the decrease in injecting risk reduced HIV incidence by 76% (63-85%) and ART further reduced HIV incidence by 8% (2-19%), or on its own by 3% (-34-37%).

Conclusions

Observed declines in HIV incidence in Vancouver between 1996 and 2007 should be seen as a success for intensive harm reduction, whereas ART probably played a small role.

Risk factors associated with HIV/HCV infection among entrants in methadone maintenance treatment clinics in China: a systematic review and meta-analysis

BACKGROUND

Methadone maintenance treatment (MMT) has rapidly expanded in China, from 8 pilot sites to 696 clinics covering 27 provinces, during 2004-2010. This study evaluates the demographic characteristics and drug use behaviors associated with Human Immunodeficiency Virus (HIV) and Hepatitis C Virus (HCV) infections among MMT entrants through a systematic review and meta-analysis of published literature.

METHODS

Thirty-nine eligible articles (1 in English and 38 in Chinese) were selected for this review. We extracted the relevant indicator information from all eligible studies and performed meta-analyses, by stratifying according to sex of the participants, age groups and drug use behaviors. Five provinces (i.e., Yunnan, Guizhou, Sichuan, Guangxi and Xinjiang) with the population size of HIV-infected drug users greater than 10,000 were defined as high transmission areas (HTAs) for HIV infection; whereas the remaining twenty-six Chinese provinces were considered as low transmission areas (LTAs).

RESULTS

The odds of being infected by HIV among male drug users were significantly higher than for females in high transmission areas (OR=1.49, 95% CI: 1.11-1.99, k=9), while the opposite results were observed in low transmission areas (OR=0.46, 0.27-0.79, k=11). In comparison, no significant differences in risk behaviors were found between sexes in HTAs and LTAs. Younger age was not associated with risk of HIV infection, but was associated with higher risk of HCV infection (<30 years OR=1.88; 30-40 years OR=2.21, compared with >40 years, k=17). Risk of HIV infection was higher among injectors than non-injectors (OR=4.29, 2.70-6.79, k=14) and for those who inject, there was greater risk among sharers than non-sharers (OR=2.47, 1.44-4.23, k=4). Similar patterns were also observed in HCV infection (injectors: OR=10.82, 7.60-15.40; sharers: OR=3.41, 2.56-4.54, k=7).

CONCLUSIONS

Characteristics of MMT entrants positive for HIV or HCV in China vary by disease types, geographical region, sex, age, and injecting behavior. These factors need to be considered in targeted interventions for MMT participants, such as age-specific health education and psychological treatment, antiretroviral therapy and needle-syringe exchange programs.

Opiate substitution treatment and HIV transmission in people who inject drugs: systematic review and meta-analysis

OBJECTIVE

To quantify the effect of opiate substitution treatment in relation to HIV transmission among people who inject drugs.

DESIGN

Systematic review and meta-analysis of prospective published and unpublished observational studies.

DATA SOURCES

Search of Medline, Embase, PsychINFO, and the Cochrane Library from the earliest year to 2011 without language restriction.

REVIEW METHODS

We selected studies that directly assessed the impact of opiate substitution treatment in relation to incidence of HIV and studies that assessed incidence of HIV in people who inject drugs and that might have collected data regarding exposure to opiate substitution treatment but not have reported it. Authors of these studies were contacted. Data were extracted by two reviewers and pooled in a meta-analysis with a random effects model.

RESULTS

Twelve published studies that examined the impact of opiate substitution treatment on HIV transmission met criteria for inclusion, and unpublished data were obtained from three additional studies. All included studies examined methadone maintenance treatment. Data from nine of these studies could be pooled, including 819 incident HIV infections over 23,608 person years of follow-up. Opiate substitution treatment was associated with a 54% reduction in risk of HIV infection among people who inject drugs (rate ratio 0.46, 95% confidence interval 0.32 to 0.67; P<0.001). There was evidence of heterogeneity between studies (I(2)=60%, χ(2)=20.12, P=0.010), which could not be explained by geographical region, site of recruitment, or the provision of incentives. There was weak evidence for greater benefit associated with longer duration of exposure to opiate substitution treatment.

CONCLUSION

Opiate substitution treatment provided as maintenance therapy is associated with a reduction in the risk of HIV infection among people who inject drugs. These findings, however, could reflect comparatively high levels of motivation to change behaviour and reduce injecting risk behaviour among people who inject drugs who are receiving opiate substitution treatment.

Sexual mixing patterns and heterosexual HIV transmission among African Americans in the southeastern United States

OBJECTIVES

Heterosexually transmitted HIV infection rates are disproportionately high among African Americans. HIV transmission is influenced by sexual network characteristics, including sexual partnership mixing patterns among subpopulations with different prevalences of infection.

STUDY DESIGN

We conducted a cross-sectional analysis of previously collected data from a North Carolina population-based case-control study. Respondents were heterosexual black men and women who either had recently reported heterosexually transmitted HIV infection (cases) or were randomly selected from the general population (controls).

METHODS

Respondents reported their own and their 3 most recent sex partners' education and involvement in illicit drug use, concurrent sex partners, and incarceration. We examined sexual mixing patterns by comparing the characteristics and behaviors of respondents reported for themselves with those they reported for their partners. We estimated Newman assortativity coefficient (-1.0 to 1.0) as an aggregate quantitative assessment of mixing patterns.

RESULTS

Across the 4 strata (male and female cases, male and female controls), mixing was assortative (0.31-0.45) with respect to illicit drug use and minimally assortative with respect to having concurrent partners (0.14-0.22). Mixing patterns for incarceration were assortative for men (0.18 and 0.41) but not women (0.07 and 0.08). Mixing with respect to education was assortative primarily for male controls (0.33).

CONCLUSIONS

These sexual partnership patterns, driven in part by the social and economic context of life for African Americans, likely contribute to the heterosexually transmitted HIV epidemic.

High prevalence of unprotected sex among Finnish HIV-positive and HIV-negative injecting drug users

AIMS

To study the prevalence of sexual risk behaviour and to identify factors associated with inconsistent condom use of Finnish injecting drug users (IDUs), and thus to examine the potential of sexual transmission of HIV within and from this population.

METHODS

HIV-positive (n = 89) and HIV-negative (n = 207) IDUs from the Helsinki metropolitan area were interviewed using a standardized questionnaire. Determinants of inconsistent condom use in the past 6 months were analyzed with logistic regression.

RESULTS

Inconsistent condom use was reported by 63% (39) of HIV-positive and 80% (144) of HIV-negative sexually active IDUs. Unprotected sex was more common in steady relationships (OR 5.6, CI 2.4-13.4). Inconsistent condom use was also associated with recent inpatient addiction treatment especially in the HIV-positive group (OR 15.7, 95% CI 1.7-143.0). Inpatient or outpatient addiction treatment was reported by 72% of the participants. Inconsistent condom use was not associated with age, gender, drug use frequency or markers of marginalization (unstable living, unemployment).

CONCLUSIONS

Inconsistent condom use allows for the spread of HIV and other sexually transmitted infections among Finnish IDUs. Addiction treatment programmes should include interventions focused on sexual behaviour to all of their clients. Partners of IDUs should be actively offered HIV counselling and testing.

Incidence of HIV, hepatitis C and hepatitis B viruses among injection drug users in southwestern China: a 3-year follow-up study

OBJECTIVE

To investigate the incidence rates of HIV, hepatitis C virus (HCV), and hepatitis B virus (HBV) among injection drug users (IDU) in a drug trafficking city in southwest China.

DESIGN

A prospective cohort study.

METHODS

A cohort of 333 HIV-seronegative IDU was followed for 36 months from November 2002 and evaluated every 6 months for seroconversions to HIV and HCV antibodies as well as hepatitis B surface antigen. Questionnaire interviews were conducted to collect information about risk behaviors.

RESULTS

Some 68.8% of subjects completed the last follow-up survey. A total of 14 HIV, 47 HCV and 51 HBV seroconversions were observed over the 36-month follow-up period, yielding average incidence rates of 2.3 per 100 person-years for HIV, 33.3 for HCV and 11.3 for HBV. Multivariate Poisson regression analyses showed that factors independently associated with HIV seroconversion were minority ethnicity and greater frequent sharing of needles or syringes in the past 3 months one or more times per week. Predictors of HCV seroconversion included being female, greater frequent drug use in the past 3 months seven or more times per week, and frequent sharing of needles or syringes in the past 3 months one or more times per week.

CONCLUSION

Blood-borne infections continue to spread, but at lower rates with time among IDU in a southwestern Chinese city where intervention programmes have existed for a few years. Rigorous implementation of harm reduction programmes may have reduced seroconversion to blood-borne infections among targeted high-risk populations.