HIV prevalence and risk behaviors among men who have sex with men and inject drugs in San Francisco

Injection drug use and sexually transmitted infections among men who have sex with men: A retrospective cohort study at an HIV/AIDS referral hospital in Tokyo, 2013-2022

Men who have sex with men (MSM) who use injection drugs (MSM-IDU) are at high risk of sexually transmitted infections (STIs), but the long-term incidence is unclear. We conducted a single-centre retrospective cohort study using the clinical records of non-haemophilia men with human immunodeficiency virus (HIV) who visited the Institute of Medical Science, the University of Tokyo (IMSUT) Hospital, located in Tokyo, Japan, from 2013 to 2022. We analysed 575 patients including 62 heterosexual males and 513 MSM patients, of whom 6.8% (35/513) were injection drug use (IDU). Compared to non-IDU MSM, MSM-IDU had a higher incidence of hepatitis C virus (HCV) (44.8 vs 3.5 /1,000 person-years (PY); incidence rate ratio (IRR) [95% confidence interval (95% CI)], 12.8 [5.5-29.3], p < 0.001) and syphilis (113.8 vs 53.3 /1,000 PY; IRR, 2.1 [1.4-3.1], p < 0.001). The incidence of other symptomatic STIs (amoebiasis, chlamydia, and gonorrhoea infections) was <4/1,000 PY. In multivariable Poisson regression analysis, HCV incidence was associated with MSM (IRR, 1.8 × 106 [9.9 × 105-3.4 × 106], p < 0.001), IDU (IRR, 10.1 [4.0-25.6], p < 0.001), and syphilis infection during the study period (IRR, 25.0 [1.2-518.3]/time/year, p < 0.001). Among men with HIV, the prevalence of IDU in MSM and the long-term incidence of STIs in MSM-IDU were high. IDU and sexual contact are important modes of transmission of HCV among HIV-infected MSM in Tokyo.

Gender, sexual orientation identity, and initiation of amphetamine injecting among people who inject drugs: Examination of an expanding drug era in Montreal, Canada, 2011-19

BACKGROUND

Amphetamine injection is expanding in North America and has been associated with male homosexuality among people who inject drugs (PWID). Applying subcultural evolution theory, we examined overall and gender-stratified trends in amphetamine injection and assessed sexual orientation as a gender-specific predictor of initiation among PWID in Montreal, Canada.

METHODS

Data were from HEPCO, an open prospective cohort of PWID. Gender and sexual orientation were self-identified at enrolment. Interviewer-administered questionnaires at three-monthly (HCV RNA-negative participants) or yearly (RNA-positive) intervals captured past three-month amphetamine injection and covariates. Annual prevalence and linear trends in amphetamine injection were estimated using GEE. Incidence was computed among naïve individuals and hazard ratios for initiation estimated using gender-stratified, time-varying Cox regression models.

RESULTS

803 participants contributed 8096 observations between March 2011 and December 2019. Annual prevalence of amphetamine injecting increased from 3.25% [95%CI: 2.06-4.43%] to 12.7% [9.50-16.0] (trend p<0.001). Bivariate Cox regression models suggested similar and divergent predictors of initiation by gender. Incidence was 3.27 per 100 person-years [95%CI: 2.51-4.18] among heterosexual men, 7.18 [3.50-13.2] among gay/bisexual men, 1.93 [0.78-4.02] among heterosexual women and 5.30 [1.69-12.8] among gay/bisexual women. Among men, gay/bisexual identity doubled risk of initiation after adjusting for age, ethnicity, calendar year (aHR 2.16 [1.07-4.36]) and additional covariates (2.56 [1.24-5.30]). Among women, evidence for an association with gay/bisexual identity was inconclusive (aHR 2.63 [0.62-11.2]) and sample size precluded further adjustment CONCLUSIONS: Prevalence of amphetamine injection among PWID increased four-fold from 2011 to 2019, with elevated risk of initiation in gay and bisexual men.

Predicting the Effectiveness of Endemic Infectious Disease Control Interventions: The Impact of Mass Action versus Network Model Structure

BACKGROUND

Analyses of the effectiveness of infectious disease control interventions often rely on dynamic transmission models to simulate intervention effects. We aim to understand how the choice of network or compartmental model can influence estimates of intervention effectiveness in the short and long term for an endemic disease with susceptible and infected states in which infection, once contracted, is lifelong.

METHODS

We consider 4 disease models with different permutations of socially connected network versus unstructured contact (mass-action mixing) model and heterogeneous versus homogeneous disease risk. The models have susceptible and infected populations calibrated to the same long-term equilibrium disease prevalence. We consider a simple intervention with varying levels of coverage and efficacy that reduces transmission probabilities. We measure the rate of prevalence decline over the first 365 d after the intervention, long-term equilibrium prevalence, and long-term effective reproduction ratio at equilibrium.

RESULTS

Prevalence declined up to 10% faster in homogeneous risk models than heterogeneous risk models. When the disease was not eradicated, the long-term equilibrium disease prevalence was higher in mass-action mixing models than in network models by 40% or more. This difference in long-term equilibrium prevalence between network versus mass-action mixing models was greater than that of heterogeneous versus homogeneous risk models (less than 30%); network models tended to have higher effective reproduction ratios than mass-action mixing models for given combinations of intervention coverage and efficacy.

CONCLUSIONS

For interventions with high efficacy and coverage, mass-action mixing models could provide a sufficient estimate of effectiveness, whereas for interventions with low efficacy and coverage, or interventions in which outcomes are measured over short time horizons, predictions from network and mass-action models diverge, highlighting the importance of sensitivity analyses on model structure.

HIGHLIGHTS

• We calibrate 4 models-socially connected network versus unstructured contact (mass-action mixing) model and heterogeneous versus homogeneous disease risk-to 10% preintervention disease prevalence.• We measure the short- and long-term intervention effectiveness of all models using the rate of prevalence decline, long-term equilibrium disease prevalence, and effective reproduction ratio.• Generally, in the short term, prevalence declined faster in the homogeneous risk models than in the heterogeneous risk models.• Generally, in the long term, equilibrium disease prevalence was higher in the mass-action mixing models than in the network models, and the effective reproduction ratio was higher in network models than in the mass-action mixing models.

The Pre-exposure Prophylaxis (PrEP) Care Cascade in People Who Inject Drugs: A Systematic Review

Injection drug use is a key risk factor for the transmission of HIV. Prevention strategies, such as the use of pre-exposure prophylaxis (PrEP), are effective at reducing the risk of HIV transmission in people who inject drugs (PWID). Following PRISMA guidelines, a literature search was conducted to identify the current state of the PrEP care cascade in PWID. Twenty-three articles were evaluated in this systematic review. A decline in engagement throughout the stages of the PrEP care cascade was found. High awareness and willingness to use PrEP was found, yet PrEP uptake was relatively low (0-3%). There is a lack of research on interventions to increase engagement of PrEP across all levels of the care cascade in PWID. Implications from the interventions that have been published provide insight into practice and public policy on efficacious strategies to reduce HIV incidence in PWID. Our findings suggest that more efforts are needed to identify and screen PWID for PrEP eligibility and to link and maintain them with appropriate PrEP care.

Correlates of Transactional Sex and Violent Victimization among Men Who Inject Drugs in Los Angeles and San Francisco, California

Men who inject drugs (MWID) and engage in transactional sex (i.e., receive money or drugs in exchange for sex) are vulnerable to HIV and violence. However, MWID who engage in transactional sex have been less studied than women. We examine factors associated with transactional sex among MWID in Los Angeles and San Francisco and whether transactional sex is associated with violent victimization. MWID were recruited using targeted sampling methods in 2011-2013 and completed surveys that covered demographics, drug use, HIV risk, violence, transactional sex, and other items. Multivariable logistic regression was used to (1) determine factors independently associated with transactional sex and (2) determine if transactional sex was independently associated with violence victimization in the last 6 months among MWID. An interaction term between income source and sexual identity was included in the transactional sex model. Of the 572 male PWID in the sample, 47 (8%) reported transactional sex in the past 6 months. Self-reported HIV infection was 7% for MWID who did not report transactional sex, 17% for MWID who reported transactional sex, and 24% for MWID who reported transactional sex and reported gay or bisexual identity. In multivariable analysis, transactional sex was positively associated with gay or bisexual identity (GB without illegal income adjusted odds ratio [AOR] = 5.16; 95% confidence interval [CI] = 1.86-14.27; GB with illegal income AOR = 13.55, CI = 4.57-40.13), coerced sex in the last 12 months (AOR = 11.66, CI = 1.94-70.12), and violent victimization in the last 12 months (AOR = 2.31, CI = 1.13-4.75). Transactional sex was negatively associated with heroin injection (last 30 days) (AOR = 0.37; 95% CI = 0.18-0.78). Transactional sex was independently associated with violent victimization in the last 12 months (AOR = 2.04; 95% CI = 1.00-4.14) while controlling for confounders. MWID who engaged in transactional sex are at elevated risk for HIV and multiple forms of violent victimization. Interventions focused on this at-risk subpopulation are urgently needed and should include access to substance use disorder treatment, victimization services, and harm reduction services across the HIV care continuum.

Distributive Syringe Sharing and Use of Syringe Services Programs (SSPs) Among Persons Who Inject Drugs

Monitoring distributive syringe sharing (DSS) and syringe services program (SSP) use among persons who inject drugs (PWID) is important for HIV prevention. PWID aged ≥ 18 in 20 US cities were recruited for National HIV Behavioral Surveillance in 2015 using respondent-driven sampling, interviewed and offered HIV testing. Bivariate and multivariable analyses via log-linked Poisson regression with generalized estimating equations were conducted to examine associations between demographic and behavioral variables and DSS. Effect of SSP use on DSS by HIV sero-status was assessed by including an interaction between SSP and sero-status. Analyses were adjusted for sampling design. Among 10,402 PWID, 42% reported DSS. DSS was less likely to be reported among HIV-positive compared to HIV-negative PWID (aPR = 0.51, CI 0.45-0.60), and among those who primarily obtained syringes from SSPs versus those who did not (aPR = 0.82, 95% CI 0.77-0.88). After adjustment, those who primarily used SSPs were less likely to report DSS than those who did not among both HIV-negative PWID (aPR = 0.84, 95% CI 0.78-0.90) and HIV-positive PWID (aPR = 0.54, 95% CI 0.39-0.75). Findings support expansion of SSPs, and referrals to SSPs by providers working with PWID.

Characterizing Men Who Have Sex with Men and Use Injection Drugs in Vancouver, Canada

We examined factors associated with reporting sex with men among men who inject drugs in Vancouver, Canada. Data were drawn from three open prospective cohorts of people who use drugs between 2005 and 2014. Generalized estimating equations were used to identify factors associated with reporting non-transactional sex with men (MSM) in the previous 6 months. Of 1663 men who used injection drugs, 225 (13.5%) were MSM over the study period. Sex with men was independently associated with younger age [Adjusted Odds Ratio (AOR) = 0.96], childhood sexual abuse (AOR = 2.65), sex work (AOR = 3.33), crystal methamphetamine use (AOR = 1.30), borrowing used syringes (AOR = 1.39), inconsistent condom use (AOR = 1.76), and HIV seropositivity (AOR = 3.82). MSM were less likely to be Hepatitis C-positive (AOR = 0.43) and to have accessed addiction treatment in the previous 6 months (AOR = 0.83) (all p < 0.05). Findings highlight vulnerabilities and resiliencies among MSM-PWID and indicate a need for trauma-informed and affirming harm reduction and substance use treatment services for MSM-PWID.

Associations between Sociodemographic Characteristics and Sexual Risk Behaviors among Methamphetamine-using Men who Have Sex with Men

BACKGROUND

Methamphetamine-using men who have sex with men (MSM) exhibit elevated rates of HIV and STI prevalence, indicating increased engagement in sexual risk behaviors.

OBJECTIVES

This analysis elucidates associations between participant sociodemographics (i.e., age, racial/ethnic identity, sexual identity, educational attainment, and HIV status) and sexual risk behaviors, particularly substance use before/during sex, and engagement in condomless anal intercourse (CAI) with casual, anonymous, and/or exchange male partners.

METHODS

From March 2014 through January 2016, 286 methamphetamine-using MSM enrolled in a technology-based study to reduce methamphetamine use and HIV sexual risk behaviors. A robustly estimated generalized structural equation model employing the negative binomial family and log link function (n = 282) tested the simultaneous associations between participant sociodemographics and engagement in HIV sexual risk behaviors.

RESULTS

Participants' racial/ethnic identity (χ²₍₆₎ = 43.5; p < 0.0001), HIV status (χ²₍₆₎ = 22.0; p = 0.0012), educational attainment level (χ²₍₆₎ = 13.8; p = 0.0322), and years of age (χ²₍₆₎ = 32.4; p < 0.0001) all influenced participants' engagement in substance use before/during sex and engagement in CAI. Methamphetamine (χ²₍₂₎ = 7.0; p = 0.0309) and marijuana (χ²₍₂₎ = 9.7; p = 0.0079) use before/during sex influenced participants' engagement in CAI with casual, anonymous, and exchange male partners.

CONCLUSION

Results indicate the importance of intervention efforts focused on younger racial/ethnic minority MSM with fewer years of educational attainment, and provides evidence of the specific subpopulations of MSM at greatest risk of detrimental effects of illicit substance use.

HIV infection among MSM who inject methamphetamine in 8 US cities

BACKGROUND AND AIMS

Men who have sex with men (MSM) and inject drugs are at risk for HIV infection. Although research exists on non-injection methamphetamine (meth) use and sexual risk among MSM, less is known about meth injection and its association with HIV infection among MSM who inject drugs.

METHODS

We analyzed data from men aged ≥18 years who reported injecting drugs and male-to-male sexual contact. Men were recruited using respondent-driven sampling, interviewed, and tested for HIV during the 2012 and 2015 cycles of National HIV Behavioral Surveillance among persons who inject drugs. We included data from 8 cities where ≥10 MSM reported meth as the primary drug injected. We assessed differences in demographic characteristics, past 12 months risk behaviors, and HIV infection between MSM who primarily injected meth and those who primarily injected another drug.

RESULTS

Among 961 MSM, 33.7% reported meth as the drug they injected most often. Compared to MSM who primarily injected other drugs, MSM who primarily injected meth were more likely to have had ≥5 condomless anal sex partners, have been diagnosed with syphilis, and were less likely to report sharing syringes. In multivariable analysis, injecting meth was associated with being HIV-positive (adjusted prevalence ratio 1.48; 95% confidence interval 1.08-2.03). Including number of condomless anal sex partners in mediation analysis rendered this association no longer significant.

CONCLUSIONS

HIV prevalence among MSM who primarily injected meth was almost 50% higher than among MSM who primarily injected other drugs, and this association was mediated by sexual risk.

The Cost-Effectiveness of Human Immunodeficiency Virus Testing and Treatment Engagement Initiatives in British Columbia, Canada: 2011-2013

Background

Recognition of the secondary preventive benefits of antiretroviral therapy (ART) has mobilized global efforts to "seek, test, treat, and retain" people living with human immunodeficiency virus [HIV]/AIDS (PLHIV) in HIV care. We aimed to determine the cost-effectiveness of a set of HIV testing and treatment engagement interventions initiated in British Columbia, Canada, in 2011-2013.

Methods

Using a previously validated dynamic HIV transmission model, linked individual-level health administrative data for PLHIV, and aggregate-level HIV testing data, we estimated the cost-effectiveness of primary care testing (hospital, emergency department [ED], outpatient), ART initiation, and ART retention initiatives vs a counterfactual scenario that approximated the status quo. HIV incidence, mortality, costs (in 2015$CDN), quality-adjusted life years (QALYs), and incremental cost-effectiveness ratios were estimated. Analyses were executed over 5- to 25-year time horizons from a government-payer perspective.

Results

ED testing was the best value at $30216 per QALY gained and had the greatest impact on incidence and mortality among PLHIV, while ART initiation provided the greatest QALY gains. The ART retention initiative was not cost-effective. Delivered in combination at the observed scale and sustained throughout the study period, we estimated a 12.8% reduction in cumulative HIV incidence and a 4.7% reduction in deaths among PLHIV at $55258 per QALY gained. Results were most sensitive to uncertainty in the number of undiagnosed PLHIV.

Conclusions

HIV testing and ART initiation interventions were cost-effective, while the ART retention intervention was not. Developing strategies to reengage PLHIV lost to care is a priority moving forward.

Estimation of the cost-effectiveness of HIV prevention portfolios for people who inject drugs in the United States: A model-based analysis

BACKGROUND

The risks of HIV transmission associated with the opioid epidemic make cost-effective programs for people who inject drugs (PWID) a public health priority. Some of these programs have benefits beyond prevention of HIV-a critical consideration given that injection drug use is increasing across most United States demographic groups. To identify high-value HIV prevention program portfolios for US PWID, we consider combinations of four interventions with demonstrated efficacy: opioid agonist therapy (OAT), needle and syringe programs (NSPs), HIV testing and treatment (Test & Treat), and oral HIV pre-exposure prophylaxis (PrEP).

METHODS AND FINDINGS

We adapted an empirically calibrated dynamic compartmental model and used it to assess the discounted costs (in 2015 US dollars), health outcomes (HIV infections averted, change in HIV prevalence, and discounted quality-adjusted life years [QALYs]), and incremental cost-effectiveness ratios (ICERs) of the four prevention programs, considered singly and in combination over a 20-y time horizon. We obtained epidemiologic, economic, and health utility parameter estimates from the literature, previously published models, and expert opinion. We estimate that expansions of OAT, NSPs, and Test & Treat implemented singly up to 50% coverage levels can be cost-effective relative to the next highest coverage level (low, medium, and high at 40%, 45%, and 50%, respectively) and that OAT, which we assume to have immediate and direct health benefits for the individual, has the potential to be the highest value investment, even under scenarios where it prevents fewer infections than other programs. Although a model-based analysis can provide only estimates of health outcomes, we project that, over 20 y, 50% coverage with OAT could avert up to 22,000 (95% CI: 5,200, 46,000) infections and cost US$18,000 (95% CI: US$14,000, US$24,000) per QALY gained, 50% NSP coverage could avert up to 35,000 (95% CI: 8,900, 43,000) infections and cost US$25,000 (95% CI: US$7,000, US$76,000) per QALY gained, 50% Test & Treat coverage could avert up to 6,700 (95% CI: 1,200, 16,000) infections and cost US$27,000 (95% CI: US$15,000, US$48,000) per QALY gained, and 50% PrEP coverage could avert up to 37,000 (22,000, 58,000) infections and cost US$300,000 (95% CI: US$162,000, US$667,000) per QALY gained. When coverage expansions are allowed to include combined investment with other programs and are compared to the next best intervention, the model projects that scaling OAT coverage up to 50%, then scaling NSP coverage to 50%, then scaling Test & Treat coverage to 50% can be cost-effective, with each coverage expansion having the potential to cost less than US$50,000 per QALY gained relative to the next best portfolio. In probabilistic sensitivity analyses, 59% of portfolios prioritized the addition of OAT and 41% prioritized the addition of NSPs, while PrEP was not likely to be a priority nor a cost-effective addition. Our findings are intended to be illustrative, as data on achievable coverage are limited and, in practice, the expansion scenarios considered may exceed feasible levels. We assumed independence of interventions and constant returns to scale. Extensive sensitivity analyses allowed us to assess parameter sensitivity, but the use of a dynamic compartmental model limited the exploration of structural sensitivities.

CONCLUSIONS

We estimate that OAT, NSPs, and Test & Treat, implemented singly or in combination, have the potential to effectively and cost-effectively prevent HIV in US PWID. PrEP is not likely to be cost-effective in this population, based on the scenarios we evaluated. While local budgets or policy may constrain feasible coverage levels for the various interventions, our findings suggest that investments in combined prevention programs can substantially reduce HIV transmission and improve health outcomes among PWID.

Impact of Tailored Interventions to Reduce Drug Use and Sexual Risk Behaviors Among Homeless Gay and Bisexual Men

A randomized controlled trial was conducted with homeless gay and bisexual men to assess the impact of two culturally sensitive intervention programs on reduction of drug use and risky sexual behavior. In this study, gay and bisexual men between 18 and 46 years of age were randomly assigned to one of two culturally sensitive behavioral intervention programs: a Nurse Case Management Plus Contingency Management (NCM + CM; n = 204) or a Standard Education Plus Contingency Management (SE + CM; n = 210) program. Regardless of group assignment, significant and clinically relevant reductions were observed in stimulant use over time. Multivariable predictors of stimulant use at 4- and 8-month follow-up evaluations were recent injection drug use, tested positive for HIV, or for use of amphetamine. Data revealed a significant linear decline over time for those who had sex with multiple partners. Furthermore, being HIV positive was associated with reporting multiple partners, while higher homophobia scores and having children were inversely related to reports of having sex with multiple partners at follow-up. Culturally sensitive approaches are needed to successfully reduce drug use and risky sexual activities among gay and bisexual populations.

The Prevalence and Correlates of HIV and Undiagnosed Infection among Men Who Have Sex with Men in Hanoi, Vietnam: Findings from a Cross-sectional, Biobehavioral Study

INTRODUCTION

Men who have sex with men (MSM) are a key population for HIV infection in Vietnam, and the use of amphetamine type substances (ATS) is prevalent and possibly increasing in this population. The reported analysis examines the association between ATS use before or during sex and HIV infection among MSM in Hanoi, Vietnam.

METHODS

This cross-sectional study of 210 MSM was conducted in Hanoi, Vietnam, in late 2014. Men tested for HIV and answered questions about demographic characteristics, sexual sensation seeking, depression, belief in HIV prevention strategies, homosexuality-related stigma and discrimination, recent accessing of HIV prevention services, sexual behaviors and ATS, and other drug use behaviors. We performed logistic regression to assess correlates of HIV infection.

RESULTS

HIV prevalence was 6.7% (14/210), and 85.7% (12/14) of HIV-positive men were not aware of their HIV status. Of the 210 participants, 10.5, 2.9, and 3.8% of men had used methamphetamine, amphetamine, and ecstasy before or during sex in the last 3 months. In multivariable analysis, HIV infection was associated with recent sex-related methamphetamine use [adjusted odds ratio (AOR): 5.03, 95% confidence interval (CI): 1.35-18.68], engaging in recent sex work (AOR: 3.55, 95% CI: 1.07-11.75), and homosexuality-related perceived stigma (AOR: 2.32, 95% CI: 0.98-5.47).

CONCLUSION

Findings underscore the importance of integrating methamphetamine use interventions into HIV prevention services and scaling-up of gay-friendly, non-stigmatizing HIV testing services for MSM in Hanoi. We recommend the routine assessment of ATS use and undiagnosed infection in this population.

Correlates of sex trading among male non-injecting drug users in Myanmar: a cross-sectional study

BACKGROUND

Sex trading is a recognized risk factor for human immune deficiency virus infection and other sexually transmitted infections among non-injecting drug users (NIDUs). However, very little research has addressed the factors associated with sex trading among male NIDUs in Myanmar.

METHODS

A cross-sectional study was conducted from January to February 2010 using the respondent-driven sampling method. In total, 210 NIDUs aged between 18 and 49 years, with no history of injecting drug use, and who used non-injected illicit drugs in the last 6 months were recruited. Face-to-face interviews were conducted using a structured questionnaire to collect information on participants' sexual and drug use behaviors. Binary and multivariate logistic regressions were applied to analyze the resulting data.

RESULTS

Of 210 NIDUs, 84 (40%) reported involvement in the sex trade during the last 3 months. In the adjusted model, factors associated with sex trade involvement included homosexual preference (adjusted odds ratio [AOR] 4.90; 95% confidence interval [CI] 1.61-14.95), having more than two partners (AOR = 3.88; 95% CI 1.55-9.72), had a regular job (AOR = 5.10; 95% CI 1.65-15.72), use of stimulant drugs rather than opiate (AOR = 2.38; 95% CI 1.10-5.15), and who used drugs more than twice per day.

CONCLUSIONS

More than one third of NIDUs were involved in sex trading. This study suggested that further comprehensive intervention programs that aim to reduce risk factors of trading sex among NIDUs may consider including NIDUs who used stimulant drugs, had regular/full-time jobs, used drugs more than twice per day, and had homosexual preferences.

Affective differences in Iowa Gambling Task performance associated with sexual risk taking and substance use among HIV-positive and HIV-negative men who have sex with men

We investigated the relationship between emotional distress and decision making in sexual risk and substance use behavior among 174 (ages 25 to 50 years, 53% black) men who have sex with men (MSM), a population at increased risk for HIV. The sample was stratified by HIV status. Measures of affective decision making, depression, anxiety, sex acts, and substance use during the past 60 days were collected at our research center. Negative binomial regression models were used to examine the relationship between age, HIV status, anxiety, depression, and IGT performance in the prediction of number of risky sex acts and substance use days. Among those without anxiety or depression, both number of risky sex acts and drug use days decreased with better performance during risky trials (i.e., last two blocks) of the IGT. For those with higher rates of anxiety, but not depression, IGT risk trial performance and risky sex acts increased concomitantly. Anxiety also interacted with IGT performance across all trials to predict substance use, such that anxiety was associated with greater substance use among those with better IGT performance. The opposite was true for those with depression, but only during risk trials. HIV-positive participants reported fewer substance use days than HIV-negative participants, but there was no difference in association between behavior and IGT performance by HIV status. Our findings suggest that anxiety may exacerbate risk-taking behavior when affective decision-making ability is intact. The relationship between affective decision making and risk taking may be sensitive to different profiles of emotional distress, as well as behavioral context. Investigations of affective decision making in sexual risk taking and substance use should examine different distress profiles separately, with implications for HIV prevention efforts.

Cost-Effectiveness of HIV Preexposure Prophylaxis for People Who Inject Drugs in the United States

BACKGROUND

The total population health benefits and costs of HIV preexposure prophylaxis (PrEP) for people who inject drugs (PWID) in the United States are unclear.

OBJECTIVE

To evaluate the cost-effectiveness and optimal delivery conditions of PrEP for PWID.

DESIGN

Empirically calibrated dynamic compartmental model.

DATA SOURCES

Published literature and expert opinion.

TARGET POPULATION

Adult U.S. PWID.

TIME HORIZON

20 years and lifetime.

INTERVENTION

PrEP alone, PrEP with frequent screening (PrEP+screen), and PrEP+screen with enhanced provision of antiretroviral therapy (ART) for individuals who become infected (PrEP+screen+ART). All scenarios are considered at 25% coverage.

OUTCOME MEASURES

Infections averted, deaths averted, change in HIV prevalence, discounted costs (in 2015 U.S. dollars), discounted quality-adjusted life-years (QALYs), and incremental cost-effectiveness ratios.

RESULTS OF BASE-CASE ANALYSIS

PrEP+screen+ART dominates other strategies, averting 26 700 infections and reducing HIV prevalence among PWID by 14% compared with the status quo. Achieving these benefits costs $253 000 per QALY gained. At current drug prices, total expenditures for PrEP+screen+ART could be as high as $44 billion over 20 years.

RESULTS OF SENSITIVITY ANALYSIS

Cost-effectiveness of the intervention is linear in the annual cost of PrEP and is dependent on PrEP drug adherence, individual transmission risks, and community HIV prevalence.

LIMITATION

Data on risk stratification and achievable PrEP efficacy levels for U.S. PWID are limited.

CONCLUSION

PrEP with frequent screening and prompt treatment for those who become infected can reduce HIV burden among PWID and provide health benefits for the entire U.S. population, but, at current drug prices, it remains an expensive intervention both in absolute terms and in cost per QALY gained.

PRIMARY FUNDING SOURCE

National Institute on Drug Abuse.

The Influence of Neurocognitive Impairment on HIV Risk Behaviors and Intervention Outcomes among High-Risk Substance Users: A Systematic Review

Neurocognitive impairment (NCI) among high-risk substance users poses a substantial barrier to reducing risk behaviors in this population. Previous work suggests that NCI is intertwined in a close, reciprocal relationship with risk behaviors. Not only does substance use worsen cognitive impairment but cognitive impairment may also reduce the efficacy of interventions aimed at reducing risk and improving medication adherence. In this systematic review, we examine the potential impact of substance abuse and cognitive functioning in the context of HIV risk behaviors and risk-reduction intervention outcomes. The findings thus far suggest that, in order to be effective, risk-reduction interventions must take into account the impact of NCI on learning, memory, and behavior.

Understanding the effects of different HIV transmission models in individual-based microsimulation of HIV epidemic dynamics in people who inject drugs

We investigated how different models of HIV transmission, and assumptions regarding the distribution of unprotected sex and syringe-sharing events ('risk acts'), affect quantitative understanding of HIV transmission process in people who inject drugs (PWID). The individual-based model simulated HIV transmission in a dynamic sexual and injecting network representing New York City. We constructed four HIV transmission models: model 1, constant probabilities; model 2, random number of sexual and parenteral acts; model 3, viral load individual assigned; and model 4, two groups of partnerships (low and high risk). Overall, models with less heterogeneity were more sensitive to changes in numbers risk acts, producing HIV incidence up to four times higher than that empirically observed. Although all models overestimated HIV incidence, micro-simulations with greater heterogeneity in the HIV transmission modelling process produced more robust results and better reproduced empirical epidemic dynamics.

Reduction in Needle Sharing Among Seattle-Area Injection Drug Users Across 4 Surveys, 1994-2013

OBJECTIVES

We evaluated time trends in sharing needles and other injection equipment from 1994 to 2013 among injection drug users in the Seattle, Washington area.

METHODS

We combined data from 4 sources: the Risk Activity Variables, Epidemiology, and Network (RAVEN) study, recruited from institutional settings; the Kiwi study, recruited from jails; National HIV Behavioral Surveillance system (NHBS) surveys, which used respondent-driven sampling; and surveys at needle-exchange sites.

RESULTS

Levels of needle sharing were higher in the earlier studies: RAVEN, 1994 to 1997 (43%) and Kiwi, 1998 to 2002 (61%). In the NHBS surveys, the initial level of 44% in 2005 declined to 31% in the period 2009 to 2012. Across needle-exchange surveys (2009-2013) the level was 21%. There was a parallel reduction in sharing other injection equipment. These trends persisted after control for sociodemographic and risk-associated variables. There was a contemporaneous increase in the number of needles distributed by local needle exchanges and a decline in the number of reported HIV cases among injection drug users.

CONCLUSIONS

The apparent long-term reduction in sharing injection equipment suggests substantial success in public health efforts to reduce the sharing of injection equipment.

Transactional Sex and the HIV Epidemic Among Men Who have Sex with Men (MSM): Results From a Systematic Review and Meta-analysis

Engagement in transactional sex has been hypothesized to increase risk of HIV among MSM, however conflicting evidence exists. We conducted a systematic review and meta-analysis comparing HIV prevalence among MSM who engaged in transactional sex to those who did not (33 studies in 17 countries; n = 78,112 MSM). Overall, transactional sex was associated with a significant elevation in HIV prevalence (OR 1.34, 95 % CI 1.11-1.62). Latin America (OR 2.28, 95 % CI 1.87-2.78) and Sub-Saharan Africa (OR 1.72, 95 % CI 1.02-2.91) were the only regions where this elevation was noted. Further research is needed to understand factors associated with sex work and subsequent HIV risk in Latin America and Sub-Saharan Africa.

Cost-effectiveness analysis of brief and expanded evidence-based risk reduction interventions for HIV-infected people who inject drugs in the United States

AIMS

Two behavioral HIV prevention interventions for people who inject drugs (PWID) infected with HIV include the Holistic Health Recovery Program for HIV+ (HHRP+), a comprehensive evidence-based CDC-supported program, and an abbreviated Holistic Health for HIV (3H+) Program, an adapted HHRP+ version in treatment settings. We compared the projected health benefits and cost-effectiveness of both programs, in addition to opioid substitution therapy (OST), to the status quo in the U.S.

METHODS

A dynamic HIV transmission model calibrated to epidemic data of current US populations was created. Projected outcomes include future HIV incidence, HIV prevalence, and quality-adjusted life years (QALYs) gained under alternative strategies. Total medical costs were estimated to compare the cost-effectiveness of each strategy.

RESULTS

Over 10 years, expanding HHRP+ access to 80% of PWID could avert up to 29,000 HIV infections, or 6% of the projected total, at a cost of $7,777/QALY gained. Alternatively, 3H+ could avert 19,000 infections, but is slightly more cost-effective ($7,707/QALY), and remains so under widely varying effectiveness and cost assumptions. Nearly two-thirds of infections averted with either program are among non-PWIDs, due to reduced sexual transmission from PWID to their partners. Expanding these programs with broader OST coverage could avert up to 74,000 HIV infections over 10 years and reduce HIV prevalence from 16.5% to 14.1%, but is substantially more expensive than HHRP+ or 3H+ alone.

CONCLUSIONS

Both behavioral interventions were effective and cost-effective at reducing HIV incidence among both PWID and the general adult population; however, 3H+, the economical HHRP+ version, was slightly more cost-effective than HHRP+.

Amphetamine-type stimulants and HIV infection among men who have sex with men: implications on HIV research and prevention from a systematic review and meta-analysis

Introduction

HIV infections and the use of amphetamine-type stimulants (ATS) among men who have sex with men (MSM) have been increasing internationally, but the role of ATS use as a co-factor for HIV infection remains unclear. We aimed to summarize the association between ATS use and HIV infection among MSM.

Methods

We conducted a systematic search of MEDLINE, EMBASE, GLOBAL HEALTH and PsycINFO for relevant English, peer-reviewed articles of quantitative studies published between 1980 and 25 April 2013. Pooled estimates of the association – prevalence rate ratios (PRR, cross-sectional studies), odds ratio (OR, case-control studies) and hazard ratio (HR, longitudinal studies), with 95% Confidence Intervals (CI) – were calculated using random-effects models stratified by study design and ATS group (meth/amphetamines vs. ecstasy). We assessed the existence of publication bias in funnel plots and checked for sources of heterogeneity using meta-regression and subgroup analysis.

Results

We identified 6710 article titles, screened 1716 abstracts and reviewed 267 full text articles. A total of 35 publications were eligible for data abstraction and meta-analysis, resulting in 56 records of ATS use. Most studies (31/35) were conducted in high-income countries. Published studies used different research designs, samples and measures of ATS use. The pooled association between meth/amphetamine use and HIV infection was statistically significant in all three designs (PRR=1.86; 95% CI: 1.57–2.17; OR=2.73; 95% CI: 2.16–3.46 and HR=3.43; 95% CI: 2.98–3.95, respectively, for cross-sectional, case-control and longitudinal studies). Ecstasy use was not associated with HIV infection in cross-sectional studies (PRR=1.15; 95% CI: 0.88–1.49; OR=3.04; 95% CI: 1.29–7.18 and HR=2.48; 95% CI: 1.42–4.35, respectively, for cross-sectional, case-control and longitudinal studies). Results in cross-sectional studies were highly heterogeneous due to issues with ATS measurement and different sampling frames.

Conclusions

While meth/amphetamine use was significantly associated with HIV infection among MSM in high-income countries in all study designs, evidence of the role of ecstasy in HIV infection was lacking in cross-sectional studies. Cross-sectional study design, measurement approaches and source populations may also be important modifiers of the strength and the direction of associations. Event-specific measure of individual drug is required to establish temporal relationship between ATS use and HIV infection. HIV prevention programmes targeting MSM should consider including interventions designed to address meth/amphetamine use.

Evidence for risk reduction among amphetamine-injecting men who have sex with men; results from national HIV behavioral surveillance surveys in the Seattle area 2008-2012

In the Seattle area men who have sex with men and also inject amphetamines (amphetamine-injecting MSM/IDU) are disproportionately likely to be infected with HIV. To characterize their distinctive characteristics, we combined data from two Seattle-area surveys of men who have sex with men (MSM) and two surveys of injection drug users (IDU). Amphetamine-injecting MSM/IDU were compared with: male IDU, MSM and other MSM/IDU. Amphetamine-injecting MSM/IDU were older than MSM but younger than IDU, more likely to be white than either group, and had an educational level higher than IDU but below MSM. They had the highest HIV prevalence (56 vs. 4-19 %). However, reported HIV cases among them fell from 92 in 1990 to 25 in 2012. They were most likely to report ten or more sex partners (49 vs. 4-26 %), an STD diagnosis (22 vs. 1-7 %) and be tested for HIV (odds ratio 1.00 vs. 0.34-0.52), and least likely to share needles (odds ratio 1.00 vs. 6.80-10.50). While sexual risk remains high, these data suggest measurable and effective risk reduction with respect to sharing injection equipment and HIV testing among Seattle-area amphetamine-injecting MSM/IDU.

Male-to-male sex among men who inject drugs in Delhi, India: overlapping HIV risk behaviours

BACKGROUND

HIV among people who inject drugs (PWID) is a major public health challenge in India. This paper examines PWID in Delhi who also have male-to-male sex with a focus on overlapping HIV risk behaviours and the psychosocial correlates of a history of male-to-male anal sex.

METHODS

We analysed data collected in April-May of 2012 from a community-based sample of 420 male PWID in Delhi obtained using time location sampling.

RESULTS

One third (37%) of the men reported a history of anal sex with men, among whom just 16% used a condom at last anal sex. Almost all (93%) participants who had a history of anal sex with men also had sex with women. Chi-square tests revealed that a history of anal sex with men was associated with a higher number of female sexual partners and sharing of needles and syringes. Additionally, unprotected sex at last sex with a male partner was significantly associated with unprotected sex at last sex with regular and paid female partners. Multivariate binary logistic regression revealed that the psychosocial correlates of a history of anal sex with other men were: being aged 18-24 (OR = 2.4, p = 0.014), illiteracy (OR = 1.9, p = 0.033), having never been married (OR = 2.6, p = 0.007), a main source of income of crime/begging (OR = 3.1, p = 0.019), a duration of injecting drug use greater than 20 years (OR = 3.4, p = 0.035) and suicidal ideation (OR = 1.7, p = 0.048).

CONCLUSION

Male-to-male sex was associated with psychosocial vulnerability, including a longer history of injecting drug use, suicidal ideation and socio-economic disadvantage. Given the extent of overlapping HIV risk behaviours, HIV programs for PWID would benefit from a strong focus on prevention of sexual HIV transmission, especially among male injectors who also have sex with other men.

Global burden of HIV among men who engage in transactional sex: a systematic review and meta-analysis

BACKGROUND

Men who engage in transactional sex, the exchange of sex for money, goods, or other items of value, are thought to be at increased risk of HIV, but there have been no systematic attempts to characterize HIV burden in this population. We undertook a systematic review and meta-analysis to quantify the burden in this population compared with that of men in the general population to better inform future HIV prevention efforts.

METHODS

We searched seven electronic databases, national surveillance reports, and conference abstracts for studies of men who engage in transactional sex published between 2004-2013. Random effects meta-analysis was used to determine pooled HIV prevalence and prevalence ratios (PR) for the difference in HIV prevalence among men who engage in transactional sex as compared to general population men.

FINDINGS

Of 66 studies included representing 31,924 men who had engaged in transactional sex in 28 countries, pooled biological assay-confirmed HIV prevalence was 10.5% (95% CI = 9.4 to 11.5%). The highest pooled HIV prevalence was in Sub-Saharan Africa (31.5%, 95% CI = 21.6 to 41.5%), followed by Latin America (19.3%, 95% CI = 15.5 to 23.1%), North America (16.6%, 95% CI = 3.7 to 29.5%), and Europe (12.2%, 95% CI = 6.0 to 17.2%). Men who engaged in transactional sex had an elevated burden of HIV compared to the general male population (PR = 20.7, 95% CI = 16.8 to 25.5).

CONCLUSIONS

The global burden of HIV is disproportionately high among men who engage in transactional sex compared with the general male population. There is an urgent need to include this population in systematic surveillance as well as to scale-up access to quality HIV prevention programs.

HIV infection and sexual risk among men who have sex with men and women (MSMW): a systematic review and meta-analysis

OBJECTIVES

To estimate the number of men who have sex with men and women who are HIV-positive in the United States, and to compare HIV prevalence rates between men who have sex with men and women, men who have sex with men only, and men who have sex with women exclusively.

METHODS

Following PRISMA guidelines, we conducted a systematic review and meta-analysis of reports referencing HIV prevalence and men who have sex with men and women. We searched PubMed and Ovid PsycINFO for peer-reviewed, U.S.-based articles reporting on HIV prevalence among men who have sex with men and women. We conducted event rate, effect size, moderation and sensitivity analyses.

RESULTS

We estimate that 1.0% of U.S. males are bisexually-behaving, and that 121,800 bisexually-behaving men are HIV-positive. Men who have sex with men and women are less than half as likely to be HIV-positive as men who have sex with men only (16.9% vs. 33.3%; OR = 0.41, 95% CI: 0.31, 0.54), but more than five times as likely to be HIV-positive as men who have sex with women exclusively (18.3% vs. 3.5%; OR = 5.71, 95% CI: 3.47, 9.39). They are less likely to engage in unprotected receptive anal intercourse than men who have sex with men only (15.9% vs. 35.0%; OR = 0.36, 95% CI: 0.28, 0.46). Men who have sex with men and women in samples with high racial/ethnic minority proportions had significantly higher HIV prevalence than their counterparts in low racial/ethnic minority samples.

CONCLUSIONS

This represents the first meta-analysis of HIV prevalence in the U.S. between men who have sex with men and women and men who have sex with men only. Data collection, research, and HIV prevention and care delivery specifically tailored to men who have sex with men and women are necessary to better quantify and ameliorate this population's HIV burden.

Association of depression, anxiety, and suicidal ideation with high-risk behaviors among men who inject drugs in Delhi, India

BACKGROUND

Sharing of needles and syringes and unprotected sex remain a common practice among people who inject drugs (PWID) in India and are important drivers of new HIV infections. Whether engagement in risk behaviors among PWID is associated with symptoms of common mental disorders in India is unknown.

METHODS

We analyzed the data collected in April and May of 2012 from a community-based sample of 420 PWID in Delhi using time location sampling. Self-report symptom scales were used to measure the severity of symptoms of depression (Patient Health Questionnaire 9) and anxiety (Generalized Anxiety Disorder scale 2) within the preceding 2 weeks. We assessed the presence of suicidal thoughts within the past 12 months.

RESULTS

PWID with severe depressive symptoms and those with suicidal thoughts were 4 and 2 times more likely to share needles/syringes, respectively. PWID experiencing suicidal thoughts had 82% more female sexual partners and were 5 times more likely to have had unprotected sex at last sex with a paid female partner. Conversely, symptoms of anxiety were associated with a 30% decrease in the likelihood of needle/syringe sharing and a 70% decrease in the likelihood of unprotected sex at last sex with a paid female partner.

CONCLUSIONS

We found a high prevalence of symptoms of depression, anxiety, and suicidal ideation among men who inject drugs in Delhi and that depression and suicidal ideation are independently positively associated with HIV risk behaviors, whereas anxiety is associated with a reduction in such behaviors. Ameliorating mental health problems among PWID in India may aid in reducing HIV infections.

Políticas de redução de danos no Brasil

Considerando a disseminação da epidemia de HIV e o controle de sua transmissão entre usuários de drogas injetáveis (UDI), estratégias de redução de danos foram incorporadas em diversos países, incluindo o Brasil. Considerando a emergência das drogas como tema central na agenda governamental, especialmente o crack, o presente artigo registra e discute as práticas observadas em um programa de pesquisa e atenção aos UDI: o UFO. Foram considerados aspectos tais como acesso e adesão do usuário, dificuldades de financiamento, sustentabilidade e avaliação de resultados. As etapas do estudo envolveram pesquisa documental, observação sistemática e entrevistas com informantes-chave. Destacamos características do UFO que poderiam contribuir para políticas de redução de danos no cenário brasileiro. O programa estudado se apresenta como um exemplo exitoso de iniciativas de redução de danos, obtendo sucesso no acesso e adesão desse grupo, favorecendo seu acesso aos serviços de saúde e prevenção de riscos associados ao uso de drogas.

30 Years on Selected Issues in the Prevention of HIV among Persons Who Inject Drugs

After 30 years of extensive research on human immunodeficiency virus (HIV) among persons who inject drugs (PWID), we now have a good understanding of the critical issues involved. Following the discovery of HIV in 1981, epidemics among PWID were noted in many countries, and consensus recommendations for interventions for reducing injection related HIV transmission have been developed. While high-income countries have continued to develop and implement new Harm Reduction programs, most low-/middle-income countries have implemented Harm Reduction at very low levels. Modeling of combined prevention programming including needle exchange (NSP) and antiretroviral therapy (ARV) suggests that NSP be given the highest priority. Future HIV prevention programming should continue to provide Harm Reduction programs for PWID coupled with interventions aimed at reducing sexual transmission. As HIV continues to spread in low- and middle-income countries, it is important to achieve and maintain high coverage of Harm Reduction programs in these locations. As PWID almost always experience multiple health problems, it will be important to address these multiple problems within a comprehensive approach grounded in a human rights perspective.

Injecting drug use among gay and bisexual men in Sydney: prevalence and associations with sexual risk practices and HIV and hepatitis C infection

Injecting drug use is commonly reported among gay and bisexual men in Australia. We examined the prevalence and covariates of injecting drug use among men participating in the Sydney Gay Community Periodic Survey between 2004-06 and 2011. In 2004-06, data was collected about which drugs were injected, while in 2011, data was collected about hepatitis C (HCV) and esoteric sexual practices. In 2004-06, 5.6 % of men reported injecting drugs in the previous 6 months; 3.4 % reported methamphetamine injection and 0.4 % heroin injection. In 2011, men who injected drugs were less likely to be employed full-time, and more likely to be HCV-positive, HIV-positive, to have used party drugs for sex, and to have engaged in esoteric sexual practices. The strong associations between injecting drug use, sexual risk practices and blood-borne virus infection suggests the need for combined sexual health and harm reduction services for gay and bisexual men who inject drugs.

A complex systems approach to evaluate HIV prevention in metropolitan areas: preliminary implications for combination intervention strategies

BACKGROUND

HIV transmission among injecting and non-injecting drug users (IDU, NIDU) is a significant public health problem. Continuing propagation in endemic settings and emerging regional outbreaks have indicated the need for comprehensive and coordinated HIV prevention. We describe the development of a conceptual framework and calibration of an agent-based model (ABM) to examine how combinations of interventions may reduce and potentially eliminate HIV transmission among drug-using populations.

METHODOLOGY/PRINCIPAL FINDINGS

A multidisciplinary team of researchers from epidemiology, sociology, geography, and mathematics developed a conceptual framework based on prior ethnographic and epidemiologic research. An ABM was constructed and calibrated through an iterative design and verification process. In the model, "agents" represent IDU, NIDU, and non-drug users who interact with each other and within risk networks, engaging in sexual and, for IDUs, injection-related risk behavior over time. Agents also interact with simulated HIV prevention interventions (e.g., syringe exchange programs, substance abuse treatment, HIV testing) and initiate antiretroviral treatment (ART) in a stochastic manner. The model was constructed to represent the New York metropolitan statistical area (MSA) population, and calibrated by comparing output trajectories for various outcomes (e.g., IDU/NIDU prevalence, HIV prevalence and incidence) against previously validated MSA-level data. The model closely approximated HIV trajectories in IDU and NIDU observed in New York City between 1992 and 2002, including a linear decrease in HIV prevalence among IDUs. Exploratory results are consistent with empirical studies demonstrating that the effectiveness of a combination of interventions, including syringe exchange expansion and ART provision, dramatically reduced HIV prevalence among IDUs during this time period.

CONCLUSIONS/SIGNIFICANCE

Complex systems models of adaptive HIV transmission dynamics can be used to identify potential collective benefits of hypothetical combination prevention interventions. Future work will seek to inform novel strategies that may lead to more effective and equitable HIV prevention strategies for drug-using populations.

Projecting HIV transmission in Japan

BACKGROUND

Little is known about the epidemiology of HIV in Japan, though newly-identified cases amongst men who have sex with men (MSM) show an increasing trend. Predictions of future trends in the HIV epidemic are essential to identify suitable interventions.

METHODS

A deterministic, compartmental model was developed that incorporated risk groups, disease stages, and treatment and testing parameters. This model was calibrated against current figures on new infections and run over 30 years to identify trends in prevalence amongst MSM, low-risk men and low-risk women. Multivariate sensitivity analysis was used to estimate sensitivity ranges for all outcomes.

RESULTS

Without new interventions amongst MSM in Japan, HIV prevalence will climb from its current rate of 2.1% to 10.4% (sensitivity range 7.4% to 18.7%), while HIV prevalence among low-risk men and women will likely decline. With small changes in safer sex behavior and testing rates, HIV prevalence can remain stable or even decline amongst MSM.

CONCLUSIONS

Japan is at risk of an epidemic of HIV amongst MSM unless significant changes are made to its current public health intervention framework. More research is necessary to understand the key drivers of the epidemic in Japan.

Risk and protective factors related to HIV-risk behavior: a comparison between HIV-positive and HIV-negative young men who have sex with men

The objective of this study was to assess and compare the prevalence of high-risk sexual behaviors among young HIV-negative (n=8064) and HIV-positive (n=171) men who have sex with men (MSM) on predictors of unprotected anal intercourse (UAI). Using venue-based time-space sampling, 8235 MSM aged 15-25 were anonymously surveyed as a part of the Community Intervention Trial for Youth (CITY). The Project was conducted in 13 communities across the USA from 1999 to 2002. Forty percent of HIV-positive men and 34% of HIV-negative men reported that they had UAI in the previous 3 months. HIV-positive MSM were more likely than their uninfected peers to have traded sex within the previous year, to have had sex while high during their last sexual encounter, and to have UAI with a greater number of partners. Multivariate analyses indicated that for HIV-negative men, positive peer norms regarding safer sex and being Black or Latino predicted avoidance of UAI. Among HIV-positive men, having social support for safer sex and positive peer norms predicted avoidance of UAI. Young HIV-positive MSM are a relevant subgroup for prevention because they constitute a significant source from which future infections could be generated.

Individual, social, and environmental factors associated with initiating methamphetamine injection: implications for drug use and HIV prevention strategies

The purpose of this study was to determine the incidence and predictors of initiating methamphetamine injection among a cohort of injection drug users (IDU). We conducted a longitudinal analysis of IDU participating in a prospective study between June 2001 and May 2008 in Vancouver, Canada. IDU who had never reported injecting methamphetamine at the study's commencement were eligible. We used Cox proportional hazards models to identify the predictors of initiating methamphetamine injection. The outcome was time to first report of methamphetamine injection. Time-updated independent variables of interest included sociodemographic characteristics, drug use patterns, and social, economic and environmental factors. Of 1317 eligible individuals, the median age was 39.9 and 522 (39.6%) were female. At the study's conclusion, 200 (15.2%) participants had initiated injecting methamphetamine (incidence density: 4.3 per 100 person-years). In multivariate analysis, age (adjusted hazard ratio [aHR]: 0.96 per year older, 95%CI: 0.95-0.98), female sex (aHR: 0.58, 95%CI: 0.41-0.82), sexual abuse (aHR: 1.63, 95%CI: 1.18-2.23), using drugs in Vancouver's drug scene epicentre (aHR: 2.15 95%CI: 1.49-3.10), homelessness (aHR: 1.43, 95%CI: 1.01-2.04), non-injection crack cocaine use (aHR: 2.06, 95%CI: 1.36-3.14), and non-injection methamphetamine use (aHR: 3.69, 95%CI: 2.03-6.70) were associated with initiating methamphetamine injection. We observed a high incidence of methamphetamine initiation, particularly among young IDU, stimulant users, homeless individuals, and those involved in the city's open drug scene. These data should be useful for the development of a broad set of interventions aimed at reducing initiation into methamphetamine injection among IDU.

Correlates of trading sex for methamphetamine in a sample of HIV-negative heterosexual methamphetamine users

While many studies have examined correlates of trading sex for money, few have examined factors associated with exclusive trading of sex for drugs. We identified sociodemographic, behavioral, and psychological correlates of trading sex for methamphetamine in a sample of HIV-negative heterosexual men and women who were enrolled in a sexual risk reduction intervention in San Diego, California. Of 342 participants, 26% overall (21% of males and 31% of females) reported trading sex for methamphetamine in the past two months. Multiple logistic regression analysis revealed that recently trading sex for methamphetamine was independently associated with being female, homeless, binging on methamphetamine, sexual victimization in the past two months, engaging in anal sex 24 or more times in the past two months, and higher sexual compulsivity scores. Effective interventions for this high-risk population should consider gender-focused counseling for sexual abuse, motivational enhancement therapy, social-cognitive skills training, as well as enhanced access and utilization of social services, including drug treatment.

The cost-effectiveness of a modestly effective HIV vaccine in the United States

BACKGROUND

The recent RV144 clinical trial showed that an ALVAC/AIDSVAX prime-boost HIV vaccine regimen may confer partial immunity in recipients and reduce transmission by 31%. Trial data suggest that efficacy may initially exceed 70% but decline over the following 3.5 years. Estimating the potential health benefits associated with a one-time vaccination campaign, as well as the projected benefits of repeat booster vaccination, may inform future HIV vaccine research and licensing decisions.

METHODS

We developed a mathematical model to project the future course of the HIV epidemic in the United States under varying HIV vaccine scenarios. The model accounts for disease progression, infection transmission, antiretroviral therapy, and HIV-related morbidity and mortality. We projected HIV prevalence and incidence over time in multiple risk groups, and we estimated quality-adjusted life years (QALYs) and costs over a 10-year time horizon. We assumed an exponentially declining efficacy curve fit to trial data, and that subsequent vaccine boosters confer similar immunity. Variations in vaccine parameters were examined in sensitivity analysis.

RESULTS

Under existing HIV prevention and treatment efforts, an estimated 590,000 HIV infections occur over 10 years. One-time vaccination achieving 60% coverage of adults could prevent 9.8% of projected new infections over 10 years (and prevent 34% of new infections in the first year) and cost approximately $91,000/QALY gained relative to the status quo, assuming $500 per vaccination series. Targeted vaccination strategies result in net cost savings for vaccines costing less than $750. One-time vaccination of 60% of all adults coupled with three-year boosters only for men who have sex with men and people who inject drugs could prevent 21% of infections for $81,000/QALY gained relative to vaccination of higher risk sub-populations only. A program attaining 90% vaccination coverage prevents 15% of new HIV cases over 10 years (and approximately 50% of infections in the first year).

CONCLUSIONS

A partially effective HIV vaccine with effectiveness similar to that observed in the RV144 trial would provide large health benefits in the United States and could meet conventionally accepted cost-effectiveness thresholds. Strategies that prioritize key populations are most efficient, but broader strategies provide greater total population health benefit.

Minimal impact of circumcision on HIV acquisition in men who have sex with men

BACKGROUND

Men who have sex with men (MSM) are disproportionately affected by HIV. The proven efficacy of circumcision in reducing the risk of HIV acquisition among African heterosexual males has raised the question of whether this protective effect may extend to MSM populations. We examined the potential impact of circumcision on an HIV epidemic within a population of MSM.

METHODS

A mathematical model was developed to simulate HIV transmission in an MSM population. The model incorporated both circumcision and seropositioning, and was used to predict the reduction in HIV prevalence and incidence as a result of the two interventions. Estimates for the time required to achieve these gains were also calculated.

RESULTS

We derive simple formulae for the decrease in HIV prevalence with increased circumcision. Our model predicts that if an initially uncircumcised MSM population in a developed country with a baseline HIV prevalence of 10% underwent universal circumcision, HIV incidence would only be reduced to 95% of pre-intervention levels and HIV prevalence to 9.6% after 20 years. In the longer term, our model predicts that prevalence would only decrease from 10% to 6%, but this would take several generations to achieve. The effectiveness of circumcision increases marginally with higher degrees of seropositioning.

CONCLUSIONS

The results of these calculations suggest that circumcision as a public health intervention will not produce a substantial decrease in HIV prevalence or incidence among MSM in the near future, and only modest reductions are achievable in the long-term.

The cost-effectiveness and population outcomes of expanded HIV screening and antiretroviral treatment in the United States

BACKGROUND

Although recent guidelines call for expanded routine screening for HIV, resources for antiretroviral therapy (ART) are limited, and all eligible persons are not currently receiving treatment.

OBJECTIVE

To evaluate the effects on the U.S. HIV epidemic of expanded ART, HIV screening, or interventions to reduce risk behavior.

DESIGN

Dynamic mathematical model of HIV transmission and disease progression and cost-effectiveness analysis.

DATA SOURCES

Published literature.

TARGET POPULATION

High-risk (injection drug users and men who have sex with men) and low-risk persons aged 15 to 64 years in the United States.

TIME HORIZON

Twenty years and lifetime (costs and quality-adjusted life-years [QALYs]).

PERSPECTIVE

Societal.

INTERVENTION

Expanded HIV screening and counseling, treatment with ART, or both.

OUTCOME MEASURES

New HIV infections, discounted costs and QALYs, and incremental cost-effectiveness ratios.

RESULTS OF BASE-CASE ANALYSIS

One-time HIV screening of low-risk persons coupled with annual screening of high-risk persons could prevent 6.7% of a projected 1.23 million new infections and cost $22,382 per QALY gained, assuming a 20% reduction in sexual activity after screening. Expanding ART utilization to 75% of eligible persons prevents 10.3% of infections and costs $20,300 per QALY gained. A combination strategy prevents 17.3% of infections and costs $21,580 per QALY gained.

RESULTS OF SENSITIVITY ANALYSIS

With no reduction in sexual activity, expanded screening prevents 3.7% of infections. Earlier ART initiation when a CD4 count is greater than 0.350 × 10(9) cells/L prevents 20% to 28% of infections. Additional efforts to halve high-risk behavior could reduce infections by 65%.

LIMITATION

The model of disease progression and treatment was simplified, and acute HIV screening was excluded.

CONCLUSION

Expanding HIV screening and treatment simultaneously offers the greatest health benefit and is cost-effective. However, even substantial expansion of HIV screening and treatment programs is not sufficient to markedly reduce the U.S. HIV epidemic without substantial reductions in risk behavior.

PRIMARY FUNDING SOURCE

National Institute on Drug Abuse, National Institutes of Health, and Department of Veterans Affairs.

The cost-effectiveness and population outcomes of expanded HIV screening and antiretroviral treatment in the United States

BACKGROUND

Although recent guidelines call for expanded routine screening for HIV, resources for antiretroviral therapy (ART) are limited, and all eligible persons are not currently receiving treatment.

OBJECTIVE

To evaluate the effects on the U.S. HIV epidemic of expanded ART, HIV screening, or interventions to reduce risk behavior.

DESIGN

Dynamic mathematical model of HIV transmission and disease progression and cost-effectiveness analysis.

DATA SOURCES

Published literature.

TARGET POPULATION

High-risk (injection drug users and men who have sex with men) and low-risk persons aged 15 to 64 years in the United States.

TIME HORIZON

Twenty years and lifetime (costs and quality-adjusted life-years [QALYs]).

PERSPECTIVE

Societal.

INTERVENTION

Expanded HIV screening and counseling, treatment with ART, or both.

OUTCOME MEASURES

New HIV infections, discounted costs and QALYs, and incremental cost-effectiveness ratios.

RESULTS OF BASE-CASE ANALYSIS

One-time HIV screening of low-risk persons coupled with annual screening of high-risk persons could prevent 6.7% of a projected 1.23 million new infections and cost $22,382 per QALY gained, assuming a 20% reduction in sexual activity after screening. Expanding ART utilization to 75% of eligible persons prevents 10.3% of infections and costs $20,300 per QALY gained. A combination strategy prevents 17.3% of infections and costs $21,580 per QALY gained.

RESULTS OF SENSITIVITY ANALYSIS

With no reduction in sexual activity, expanded screening prevents 3.7% of infections. Earlier ART initiation when a CD4 count is greater than 0.350 × 10(9) cells/L prevents 20% to 28% of infections. Additional efforts to halve high-risk behavior could reduce infections by 65%.

LIMITATION

The model of disease progression and treatment was simplified, and acute HIV screening was excluded.

CONCLUSION

Expanding HIV screening and treatment simultaneously offers the greatest health benefit and is cost-effective. However, even substantial expansion of HIV screening and treatment programs is not sufficient to markedly reduce the U.S. HIV epidemic without substantial reductions in risk behavior.

PRIMARY FUNDING SOURCE

National Institute on Drug Abuse, National Institutes of Health, and Department of Veterans Affairs.

Social and behavioral characteristics of HIV-positive MSM who trade sex for methamphetamine

BACKGROUND

Previous research among drug-using men who have sex with men (MSM) indicates that trading sex for methamphetamine may be common.

OBJECTIVES

This study identified background characteristics, substance use variables, contextual factors, and sexual risk behaviors associated with trading sex for methamphetamine in a sample of HIV-positive MSM. Baseline data were gathered from 155 participants who were enrolled in a sexual risk-reduction intervention. Logistic regression was used to compare MSM who traded sex for methamphetamine with men who did not.

RESULTS

Forty-three percent of the sample reported trading sex for methamphetamine in the past 2 months. Trading sex for methamphetamine was associated with being a binge user, homelessness, having an income of less than $20,000 per year, being less assertive at turning down drugs, engaging in more anal sex without a condom, and seeking out risky sex partners when high on methamphetamine.

CONCLUSION AND SCIENTIFIC SIGNIFICANCE

These data suggest that the trading of sex for methamphetamine may be a primary source of new HIV infections within and outside of the MSM community, necessitating targeted interventions with this vulnerable subgroup.

Male injecting drug users in the Deep South: bisexual behaviour is a marker for elevated HIV risk

This study determined whether bisexual male injecting drug users (IDUs) as compared with heterosexual IDUs were more likely to engage in HIV-associated risk behaviours. Respondent-driven sampling was employed to recruit a sample of 382 male IDUs residing in the southeastern USA. Data were collected in face-to-face interviews. Weighted analyses showed that bisexual IDUs in the past 12 months were 4.6 times as likely to share needles and 3.5 times as likely to share a cooker; having multiple female sexual partners and trading money or drugs for sex with women were marginally significant. Bisexual IDUs were 10 times as likely to self-report HIV. Male IDUs, who engage in bisexual behaviour, are also engaging in HIV-associated drug and to some degree sexual-risk behaviours with women more so than heterosexual IDUs. Their higher prevalence of HIV infection coupled with their risk behaviours place themselves and other IDUs at heightened risk of both acquiring and transmitting HIV.

HIV risk and the overlap of injecting drug use and high-risk sexual behaviours among men who have sex with men in Zanzibar (Unguja), Tanzania

BACKGROUND

Men who have sex with men and inject drugs (MSM-IDU) are particularly vulnerable to HIV infection and have the potential to transmit HIV across multiple populations through their male and female sexual partners and injection drug-using partners.

METHODS

Respondent-driven sampling was used to recruit men who reported engaging in anal sex with another man in the past 3 months, aged ≥15 years, and living in Unguja, Zanzibar. Participants responded to a face-to-face interview about their HIV and injecting risk behaviours and were tested for HIV, Hepatitis B (HBV) and C (HCV) and syphilis.

RESULTS

Among the 509 MSM who enrolled in the survey, 14% (n=66) reported injecting drugs in the past 3 months among which 66% used heroin, 60% used a needle after someone else had and 68% passed a needle to someone else after using it. MSM-IDU were significantly more likely to have two or more non-paying male receptive sex partners and to have engaged in group sex in the past month, to have symptoms of a sexually transmitted infection in past 6 months, to have been arrested or beaten in the past 12 months and to be infected with HIV and co-infected with HIV and HCV compared to MSM who did not inject drugs. MSM-IDU were less likely to have used a condom at last sex with a non-paid female partner, to know where to get a confidential HIV test and to have ever been tested for HIV compared to MSM who did not inject drugs.

CONCLUSION

MSM-IDU, and MSM in general, in Unguja practice multiple high-risk behaviours that put them at risk for blood-borne and sexual transmission of HIV and HCV infection. Targeted interventions for MSM-IDU must account for the overlap of high-risk sexual and drug-using networks and integrate injection drug use and HIV services.

Potential population health outcomes and expenditures of HIV vaccination strategies in the United States

Estimating the potential health benefits and expenditures of a partially effective HIV vaccine is an important consideration in the debate about whether HIV vaccine research should continue. We developed an epidemic model to estimate HIV prevalence, new infections, and the cost-effectiveness of vaccination strategies in the U.S. Vaccines with modest efficacy could prevent 300,000-700,000 HIV infections and save $30 billion in healthcare expenditures over 20 years. Targeted vaccination of high-risk individuals is economically efficient, but difficulty in reaching these groups may mitigate these benefits. Universal vaccination is cost-effective for vaccines with 50% efficacy and price similar to other infectious disease vaccines.

Simultaneous recruitment of drug users and men who have sex with men in the United States and Russia using respondent-driven sampling: sampling methods and implications

The Sexual Acquisition and Transmission of HIV Cooperative Agreement Program (SATHCAP) examined the role of drug use in the sexual transmission of the human immunodeficiency virus (HIV) from traditional high-risk groups, such as men who have sex with men (MSM) and drug users (DU), to lower risk groups in three US cities and in St. Petersburg, Russia. SATHCAP employed respondent-driven sampling (RDS) and a dual high-risk group sampling approach that relied on peer recruitment for a combined, overlapping sample of MSM and DU. The goal of the sampling approach was to recruit an RDS sample of MSM, DU, and individuals who were both MSM and DU (MSM/DU), as well as a sample of sex partners of MSM, DU, and MSM/DU and sex partners of sex partners. The approach efficiently yielded a sample of 8,355 participants, including sex partners, across all four sites. At the US sites-Los Angeles, Chicago, and Raleigh-Durham-the sample consisted of older (mean age = 41 years), primarily black MSM and DU (both injecting and non-injecting); in St. Petersburg, the sample consisted of primarily younger (mean age = 28 years) MSM and DU (injecting). The US sites recruited a large proportion of men who have sex with men and with women, an important group with high potential for establishing a generalized HIV epidemic involving women. The advantage of using the dual high-risk group approach and RDS was, for the most part, the large, efficiently recruited samples of MSM, DU, and MSM/DU. The disadvantages were a recruitment bias by race/ethnicity and income status (at the US sites) and under-enrollment of MSM samples because of short recruitment chains (at the Russian site).

Behaviorally bisexual men and their risk behaviors with men and women

Gay and bisexual men are often treated as a homogenous group; however, there may be important differences between them. In addition, behaviorally bisexual men are a potential source of HIV infection for heterosexual women. In this study, we compared 97 men who have sex with men only (MSM) to 175 men who have sex with men and women (MSMW). We also compared the 175 MSMW to 772 men who have sex with women only (MSW). Bivariate and multiple logistic regression analyses were performed to assess correlates of MSMW risk behaviors with men and with women as well as whether MSMW, compared with MSW, engaged in more risky behaviors with women. Compared with MSM, MSMW were less likely to be HIV-positive or to engage in unprotected receptive anal intercourse. In contrast, MSMW were more likely than MSW to be HIV-positive and to engage in anal intercourse with their female partners; however, rates of unprotected anal intercourse were similar. The study findings suggest that there may be important differences in HIV risk behaviors and HIV prevalence between MSM and MSMW as well as between MSMW and MSW.

Sociodemographic, sexual, and HIV and other sexually transmitted disease risk profiles of nonhomosexual-identified men who have sex with men

I examined sociodemographic, sexual, and HIV and other sexually transmitted disease risk differences among homosexual- and nonhomosexual-identified men who have sex with men (MSM) in the United States. Non-Mexican Latino ethnicity, marriage or cohabitation, religiosity, and incarceration history were positively associated with being nonhomosexual identified. Being nonhomosexual identified was associated with some risk (e.g., more sexual intercourse while intoxicated) and protective (e.g., fewer male partners) behaviors. Probabilistic sampling strategies may be useful in future research and intervention efforts.

The relationship of sexual dyad and personal network characteristics and individual attributes to unprotected sex among young injecting drug users

We examine in the heterosexual partnerships (dyads) of IDUs the correlates of engaging in unprotected sex on three levels: individual attributes, social network characteristics, and dyad characteristics. Unprotected sex was significantly less likely to occur in dyads where the participant injected daily or had high safe-sex attitude scores, and in dyads where both members encouraged each other to use condoms. Unprotected sex was significantly more likely to occur in dyads that smoked crack together, shared needles with each other, and where the participant knew that the sex partner had concurrent sex partners. In the sexual dyads of IDUs there is a combined risk of unsafe injecting and unsafe sex. Both injecting and sexual risk, and their combination need to be addressed in interventions that target the sexual partnerships of IDUs. Such interventions should also aim to reduce injected and non-injected crack and other stimulant use associated with high-risk sex.

An examination of social network characteristics of men who have sex with men who use drugs

OBJECTIVES

The purpose of this study was to compare the social network characteristics of men who have sex with men (MSM) to men who did not have sex with men (NMSM) in a sample of predominately African-American drug users. Specifically, we were interested in examining the differences in structure of the networks and drug and sexual risk partners within the network.

METHODS

Data came from 481 male participants who reported having > or =1 sex partner in the past 90 days. MSM were defined as having sex with a male. Data on social network composition were collected using a Social Network Inventory.

RESULTS

Of 481 men, 7% (n = 32) were categorised as MSM. Nearly two-thirds of MSM did not identify as gay. MSM were more likely to be HIV positive compared with NMSM. Social networks of MSM were younger and a greater proportion was HIV positive. After adjusting for HIV status, networks of MSM were less dense indicating fewer connections among network members. Among injection drug using men in the sample, MSM reported a greater number of needle sharing networks than NMSM.

CONCLUSIONS

These findings underscore the importance of including social network factors in investigations of HIV risk among MSM. Further studies should focus on dynamics within a network and how they may operate to affect behaviour and health.

Stigma and discrimination experiences of HIV-positive men who have sex with men in Cape Town, South Africa

Since the primary mode of HIV transmission in sub-Saharan Africa is heterosexual, research focusing on the sexual behaviour of men who have sex with men (MSM) is scant. Currently it is unknown how many people living with HIV in South Africa are MSM and there is even less known about the stigmatisation and discrimination of HIV-positive MSM. The current study examined the stigma and discrimination experiences of MSM living with HIV/AIDS in South Africa. Anonymous venue-based surveys were collected from 92 HIV-positive MSM and 330 HIV-positive men who only reported sex with women (MSW). Internalised stigma was high among all HIV-positive men who took part in the survey, with 56% of men reporting that they concealed their HIV status from others. HIV-positive MSM reported experiencing greater social isolation and discrimination resulting from being HIV-positive, including loss of housing or employment due to their HIV status, however these differences were not significant. Mental health interventions, as well as structural changes for protection against discrimination, are needed for HIV-positive South African MSM.