Convergence of HIV prevalence and inter-racial sexual mixing among men who have sex with men, San Francisco, 2004-2011

Intersectional Identities and HIV: Race and Ethnicity Drive Patterns of Sexual Mixing

Large disparities exist in HIV across racial and ethnic populations-with Black and Latino populations disproportionately affected. This study utilizes a large cohort of young men who have sex with men (YMSM) to examine how race and ethnicity drive sexual partner selection, and how those with intersecting identities (Latinos who identify as White or Black) differ from Latinos without a specific racial identification (Latinos who identify as "Other"). Data come from YMSM (N = 895) who reported on sexual partners (N = 3244). Sexual mixing patterns differed substantially by race and ethnicity. Latinos who self-identified as "Black" reported mainly Black partners, those who self-identified as "White" predominantly partnered with Whites, while those who self-identified as "Other" mainly partnered with Latinos. Results suggested that Black-Latino YMSM are an important population for prevention, as their HIV prevalence neared that of Black YMSM, and their patterns of sexual partnership suggested that they may bridge Black YMSM and Other-Latino YMSM populations.

A New Era of HIV Risk: It's Not What You Know, It's Who You Know (and How Infectious)

HIV is transmitted in social and sexual relationships, and HIV transmission risks, as well as protective actions, are evolving as HIV epidemics unfold. The current focus of HIV prevention is centered on antiretroviral medications used to reduce HIV infectiousness in persons already infected with HIV [treatment as prevention (TasP)]. The same medications used to treat infected persons can also be used by uninfected persons as pre-exposure prophylaxis (PrEP) to reduce the infectivity of HIV. Both PrEP and TasP are effective when adherence is high and individuals do not have co-occurring sexually transmitted infections. HIV prevention is most effective and efficient when delivered within sexual networks with high HIV prevalence. Specific network characteristics are recognized as important facilitators of HIV transmission; these characteristics include the degree of similarity among network members (homophily), gender role norms, and belief systems. Since 2011, HIV risk has been redefined based on infectiousness and infectivity, ushering in a new era of HIV prevention with the potential to end HIV epidemics.

Trends in Sexual Behavior Among Men Who have Sex with Men (MSM) in High-Income Countries, 1990-2013: A Systematic Review

HIV diagnoses among men who have sex with men (MSM) have been increasing in several high-income countries. A better understanding of the sexual behavior trends among MSM can be useful for informing HIV prevention. We conducted a systematic review of studies that examined behavioral trends (1990-2013) in any condomless anal sex, condomless anal sex with an HIV-discordant partner, and number of partners. Studies included come from the United States, Europe, and Australia. We found increasing trends in condomless anal sex and condomless anal sex with an HIV-discordant partner, and a decreasing trend in number of partners. The increase in condomless anal sex may help to explain the increase in HIV infections. More explanatory research is needed to provide insight into factors that contribute to these behavior trends. Continuous monitoring of HIV, risk behaviors, and use of prevention and treatment is needed to evaluate prevention efforts and monitor HIV transmission risk.

Closing the Gap? The HIV Continuum in Care for African-American Men Who Have Sex with Men, San Francisco, 2004-2014

We examined trends in the HIV continuum in care in the National HIV Behavioral Surveillance surveys for MSM in San Francisco from 2004 to 2014. In 2004, HIV-positive African-American MSM were less likely to be diagnosed (42.9 vs. 87.5 %, p = 0.003), linked to care (42.9 vs. 85.7 %, p = 0.007), or to have ever used antiretroviral treatment (ART) (28.6 vs. 69.6 %, p = 0.032) compared to white MSM. By 2014, these gaps had narrowed but not closed, including diagnosis (85.7 vs. 100 %, Fisher's exact p = 0.106), linkage to care (85.7 vs. 96.8 %, Fisher's exact p = 0.290), and ART use (85.7 vs. 94.9 %, Fisher's exact p = 0.369).

Social mixing and correlates of injection frequency among opioid use partnerships

BACKGROUND

As resources are deployed to address the opioid overdose epidemic in the USA, it is essential that we understand the correlates of more frequent opioid injections-which has been associated not only with HIV and HCV transmission, but also with overdose risk-to inform the development and targeting of effective intervention strategies like overdose prevention and naloxone distribution programs. However, no studies have explored how characteristics of opioid use partnerships may be associated within injection frequency with opioid partnerships.

METHODS

Using baseline data from a trial of a behavioural intervention to reduce overdose among opioid users in San Francisco, CA, we calculated assortativity among opioid use partnerships by race, gender, participant-reported HIV- and HCV-status, and opioids used using Newman's assortativity coefficient (NC). Multivariable generalized estimating equations linear regression was used to examine associations between individual- and partnership-level characteristics and injection frequency within opioid use partnerships.

RESULTS

Opioid use partnerships (n=134) reported by study participants (n=55) were assortative by race (NC=0.42, 95%CI=0.33-0.50) and participant-reported HCV-status (NC=0.42, 95%CI=0.31-0.52). In multivariable analyses, there were more monthly injections among sexual/romantic partnerships (β=114.4, 95%CI=60.2-168.7, p<0.001), racially concordant partnerships reported by white study participants (β=71.4, 95%CI=0.3-142.5, p=0.049), racially discordant partnerships reported by African American study participants (β=105.7, 95%CI=1.0-210.5, p=0.048), and partnerships in which either member had witnessed the other experience an overdose (β=81.8, 95%CI=38.9-124.6, p<0.001).

CONCLUSION

Social segregation by race and HCV-status should potentially be considered in efforts to reach networks of opioid users. Due to higher injection frequency and greater likelihood of witnessing their partners experience an overdose, individuals in sexual/romantic opioid use partnerships, white individuals in racially homogenous partnerships, and African American individuals in heterogeneous partnerships may warrant focused attention as part of peer- and network-based overdose prevention efforts, as well as broader HIV/HCV prevention strategies. Developing and targeting overdose prevention education programs that provide information on risk factors and ways to identify overdose, as well as effective responses, including naloxone use and rescue breathing, for more frequently injecting networks may help reduce opioid morbidity and mortality in these most at risk groups.

Reconciling Epidemiology and Social Justice in the Public Health Discourse Around the Sexual Networks of Black Men Who Have Sex With Men

Several studies have implicated the sexual networks of Black men who have sex with men (MSM) as facilitating disproportionally high rates of new HIV infections within this community. Although structural disparities place these networks at heightened risk for infection, HIV prevention science continues to describe networks as the cause for HIV disparities, rather than an effect of structures that pattern infection. We explore the historical relationship between public health and Black MSM, arguing that the current articulation of Black MSM networks is too often incomplete and counterproductive. Public health can offer a counternarrative that reconciles epidemiology with the social justice that informs our discipline, and that is required for an effective response to the epidemic among Black MSM.

If You Are Not Counted, You Don't Count: Estimating the Number of African-American Men Who Have Sex with Men in San Francisco Using a Novel Bayesian Approach

African-American men who have sex with men (AA MSM) have been disproportionately infected with and affected by HIV and other STIs in San Francisco and the USA. The true scope and scale of the HIV epidemic in this population has not been quantified, in part because the size of this population remains unknown. We used the successive sampling population size estimation (SS-PSE) method, a new Bayesian approach to population size estimation that incorporates network size data routinely collected in respondent-driven sampling (RDS) studies, to estimate the number of AA MSM in San Francisco. This method was applied to data from a 2009 RDS study of AA MSM. An estimate from a separate study of local AA MSM was used to model the prior distribution of the population size. Two-hundred and fifty-six AA MSM were included in the RDS survey. The estimated population size was 4917 (95% CI 1267-28,771), using a flat prior estimated 1882 (95% CI 919-2463) as a lower acceptable bound, and a large prior estimated 6762 (95% CI 1994-13,863) as an acceptable upper bound. Point estimates from the SS-PSE were consistent with estimates from multiplier methods using external data. The SS-PSE method is easily integrated into RDS studies and therefore provides a simple and appealing tool to rapidly produce estimates of the size of key populations otherwise difficult to reach and enumerate.

Trends in the HIV Epidemic Among African American Men Who Have Sex with Men, San Francisco, 2004-2011

African American men who have sex with men have been disproportionately affected by the HIV epidemic in the United States and remain to this day one of the groups with highest HIV prevalence and incidence. Our goal was to clarify the current state of HIV risk, sexual behaviors, and structural/network-network level factors that affect black MSM's population risk of HIV, enabling the formulation of targeted and up-to-date public health messages/campaigns directed at this vulnerable population. Our approach maximized the use of local data through a process of synthesis and triangulation of multiple independent and overlapping sources of information that are sometimes separately published and often not examined side-by-side. Among African American MSM, we observed stable HIV incidence despite increases in reported individual risk behavior and STDs. An increasing proportion of African American MSM are reporting HIV testing in the past 6 months and seroadaptive behaviors, which may play a role in this observed decline in HIV among MSM in San Francisco, California. Our analysis suggests that currently the HIV epidemic is stable among African American MSM in San Francisco. However, we suggest that the observed stability is due to factors prohibiting expansion of new infections rather than decreasing risks for HIV infection among African American MSM.

Consistently high HIV prevalence among men who have sex with men in Chengdu city from 2009 to 2014

To describe the trends of the HIV epidemic among men who have sex with men (MSM) in Chengdu city, China, consecutive cross-sectional surveys were conducted by the Chengdu Center for Disease Control and Prevention. These surveys were carried out between 2009 and 2014 according to the protocol of the national HIV Sentinel Surveillance System. For the 2422 MSM who participated in the survey, the overall HIV prevalence was 15.5% (375/2422, 95% CI 14.0-16.9%). Between 2009 and 2014, the HIV prevalence of MSM remained high, with HIV-positivity rates of 15.0%, 15.1%, 16.3%, 13.9%, 17.8% and 14.0% each year respectively (χ² for trend = 0.008, P = 0.931). However, the majority (89.8%) of participants had had anal sex in the six months prior to the interview, and the percentage always using condoms during anal sex increased over the study period (36.7% in 2009, 39.8% in 2010, 36.9% in 2011, 46.2% in 2012, 65.1% in 2013, 49.0% in 2014; Chi-square for trend = 49.883, P < 0.001). HIV prevalence among MSM in Chengdu city has remained high. Given the continuing high levels of unprotected anal intercourse and high HIV prevalence among MSM, more effective intervention strategies are required to increase the coverage of MSM by risk-reduction interventions and to promote HIV testing among this population.

Disassortative mixing patterns of drug-using and sex networks on HIV risk behaviour among young drug users in Yunnan, China

OBJECTIVES

The dominant mode of HIV transmission in China has changed from injection drug use to sexual contact. The objectives of this study were to describe the disassortative and assortative mixing patterns of drug-using and sex networks among young drug users in China.

STUDY DESIGN

Cross-sectional study.

METHODS

Respondent-driven sampling (RDS) was used to recruit young drug users in an egocentric network study in Yunnan, China. Egos were categorized as having disassortative mixing network patterns if they reported both sex and drug-using networks. Egos who only had a sex network (no drug-using network), or only a drug-using network (no sex network) were categorized as having assortative mixing network patterns. Multiple logistic regression was performed to analyze the relationships between disassortative patterns with risky sexual behaviour and drug-using practices.

RESULTS

A total of 426 participants were recruited into the study. Two hundred forty-two egos reported disassortative mixing patterns and 139 egos had assortative patterns. The RDS-adjusted proportion of having a disassortative pattern was 53.2%. Participants with disassortative patterns were more likely to engage in HIV risk behaviour compared to those with assortative patterns. Specifically, drug users with disassortative patterns reported more multiple sex partners (31.4% vs 19.6%), concurrent partnerships (52.1% vs 39.0%), non-regular sex partners (12.0% vs 4.3%), and sex partners who were IDUs (24.9% vs 12.5%). Consistent condom use with regular or non-regular partners was low (between 18.9% and 47.2%) regardless of the mixing pattern. However, parenteral risk for HIV transmission was relatively low in both groups.

CONCLUSIONS

The transition of the HIV epidemic in China from injection drug use to sexual contact may be attributed to disassortative mixing in drug-use and sexual networks. HIV programs should consider disassortative mixing patterns when designing new behavioural interventions.

The Role of Geographic and Network Factors in Racial Disparities in HIV Among Young Men Who have Sex with Men: An Egocentric Network Study

The objective of this study was to characterize and compare individual and sexual network characteristics of Black, White, and Latino young men who have sex with men (YMSM) as potential drivers of racial disparities in HIV. Egocentric network interviews were conducted with 175 diverse YMSM who described 837 sex partners within 167 sexual-active egos. Sexual partner alter attributes were summarized by ego. Descriptives of ego demographics, sexual partner demographics, and network characteristics were calculated by race of the ego and compared. No racial differences were found in individual engagement in HIV risk behaviors or concurrent sexual partnership. Racial differences were found in partner characteristics, including female gender, non-gay sexual orientations, older age, and residence in a high HIV prevalence neighborhood. Racial differences in relationship characteristics included type of relationships (i.e., main partner) and strength of relationships. Network characteristics also showed differences, including sexual network density and assortativity by race. Most racial differences were in the direction of effects that would tend to increase HIV incidence among Black YMSM. These data suggest that racial disparities in HIV may be driven and/or maintained by a combination of racial differences in partner characteristics, assortativity by race, and increased sexual network density, rather than differences in individual's HIV risk behaviors.

Sexual mixing and the risk environment of sexually active transgender women: data from a respondent-driven sampling study of HIV risk among transwomen in San Francisco, 2010

Background

Research on the sexual networks of transwomen is central to explaining higher HIV risk for this population. This study examined HIV risk behaviors and sexual mixing patterns of transwomen by demographic and HIV-related risk behaviors.

Methods

Data were obtained from a 2010 study of HIV risk for transwomen in San Francisco. Assortativity by race, partner type, HIV serostatus, and IDU across sexual networks was calculated using Newman’s assortativity coefficient (NC). Multivariable generalized estimating equations (GEE) logistic regression models were used to evaluate associations between unprotected anal intercourse with race and HIV serostatus, partner-IDU status and relationship type discordance while adjusting for the HIV status of transwomen.

Results

There were 235 sexually active transwomen in this study, of whom 104 (44.3%) were HIV-positive and 73 (31.1%) had a history of injection drug use. Within the 575 partnerships, African American/black and Latina transwomen were the most racially assortative (NC 0.40, 95% CI 0.34-0.45, and NC 0.43, 95% CI 0.38-0.49, respectively). In partnerships where the partner’s HIV status was known (n = 309, 53.7%), most transwomen were in sexual partnerships with people of their same known serostatus (71.8%, n = 222). In multivariable analyses, unprotected anal intercourse was significantly associated with primary partners, having a sexual partner who was an injection drug user, and sexual partner seroconcordance.

Conclusions

Public health efforts to reduce transwomen’s HIV risk would likely benefit from prioritizing prevention efforts to risk reduction within IDU-discordant and primary partnerships, determining risks attributable to sexual network characteristics, and actively addressing injection drug use among transwomen.