Number of casual male sexual partners and associated factors among men who have sex with men: results from the National HIV Behavioral Surveillance system

Dynamics and features of transmission clusters of HIV-1 subtypes in the state of São Paulo, Brazil

Background

Molecular epidemiology techniques allow us to track the HIV-1 transmission dynamics. Herein, we combined genetic, clinical and epidemiological data collected during routine clinical treatment to evaluate the dynamics and characteristics of transmission clusters of the most prevalent HIV-1 subtypes in the state of São Paulo, Brazil.

Methods

This was a cross-sectional study conducted with 2,518 persons living with HIV (PLWH) from 53 cities in São Paulo state between Jan 2004 to Feb 2015. The phylogenetic tree of protease/reverse transcriptase (PR/RT) regions was reconstructed by PhyML and ClusterPicker used to infer the transmission clusters based on Shimodaira-Hasegawa (SH) greater than 90% (phylogenetic support) and genetic distance less than 6%.

Results

Of a total of 2,518 sequences, 2,260 were pure subtypes at the PR/RT region, being B (88%), F1 (8.1%), and C (4%). About 21.2% were naïve with a transmitted drug resistance (TDR) rate of 11.8%. A total of 414 (18.3%) of the sequences clustered. These clusters were less evident in subtype B (17.7%) and F1 (15.1%) than in subtype C (40.2%). Clustered sequences were from PLWH at least 5 years younger than non-clustered among subtypes B (p < 0.001) and C (p = 0.037). Men who have sex with men (MSM) predominated the cluster in subtype B (51%), C (85.7%), and F1 (63.6%; p < 0.05). The TDR rate in clustered patients was 15.4, 13.6, and 3.1% for subtypes B, F1, and C, respectively. Most of the infections in subtypes B (80%), C (64%), and F1 (59%) occurred within the state of São Paulo. The metropolitan area of São Paulo presented a high level of endogenous clustering for subtypes B and C. The São Paulo city had 46% endogenous clusters of subtype C.

Conclusion

Our findings showed that MSM, antiretroviral therapy in Treatment-Naive (ART-naïve) patients, and HIV1-C, played an important role in the HIV epidemic in the São Paulo state. Further studies in transmission clusters are needed to guide the prevention intervention.

"I suppose in our culture, old means no sex": PLWH and healthcare provider views on factors influencing late HIV testing and diagnosis among older adults in Malaysia

The proportion of new HIV diagnoses among older adults aged ≥50 years continues to rise. Older adults are at higher risk of late diagnosis which is associated with higher treatment complexity and poorer health outcomes. Few studies in the Asia-Pacific region have explored factors contributing to late presentation and diagnosis in this population. Thus, our study aimed to explore factors influencing late HIV diagnosis among older adults ≥50 years in Malaysia. We conducted in-depth interviews with 16 older adults newly diagnosed with HIV (OPLWH) and focus group discussions with seven healthcare providers (HCPs) from different specialties in an academic tertiary hospital in Malaysia. All sessions were audio-recorded, transcribed verbatim and analysed thematically. Three main themes related to late diagnosis among OPLWH emerged: (1) challenge in recognizing HIV symptoms among older persons, (2) older persons and HCPs having low index of suspicion of HIV and (3) poor acceptance of HIV testing among older persons due to perceived personal and social identities. HCPs often missed HIV symptoms and these collectively culminated in OPLWH experiencing complex diagnostic journeys resulting in late HIV diagnosis. To reduce delays in HIV diagnosis, strategies are needed to improve HIV knowledge and risk perception among both older adults and HCPs.

Accumulation of Immunity in Heavy-Tailed Sexual Contact Networks Shapes Mpox Outbreak Sizes

Many countries affected by the global outbreak of mpox in 2022 have observed a decline in cases. Our mathematical model accounting for heavy-tailed sexual partnership distributions suggests that mpox epidemics can hit the infection-derived herd immunity threshold and begin to decline, with <1% of sexually active men who have sex with men infected regardless of interventions or behavioral changes. We consistently found that many countries and US states experienced an epidemic peak, with cumulative cases of around 0.1% to 0.5% among men who have sex with men. The observed decline in cases may not necessarily be attributable to interventions or behavioral changes primarily.

Substance use and variation in sexual partnership rates among young MSM and young transgender women: Disaggregating between and within-person associations

BACKGROUND

Substance use has been extensively linked to sexual behavior and HIV/STI risk among men who have sex with men (MSM) and transgender women (TW). However, the impact of specific substances and on specific partnership types is not well characterized. The current study seeks to estimate the association between specific substances and partnership rates while carefully disaggregating between and within-person associations to characterize the nature of these associations and inform prevention interventions.

METHODS

Using data from a longitudinal cohort (n = 1159) of young MSM (YMSM) and young TW (YTW), we utilized a series of hybrid mixed effect models to estimate the associations between substance use (i.e., heavy episodic drinking [HED], marijuana, cocaine, ecstasy, methamphetamine, poppers, prescription stimulant, prescription painkiller, and prescription depressants) and partnerships (i.e., one-time, casual, and main).

RESULTS

Results from multivariable models indicated people using substances had higher one-time (HED, poppers) and casual (HED, methamphetamine, poppers) partnership rates. In addition, participants reported higher rates of one-time (HED, ecstasy, methamphetamine, poppers) and casual partners (HED, marijuana, cocaine, methamphetamines, poppers) during periods of substance use.

CONCLUSION

These findings confirm that the highest rates of sexual activity occur among YMSM-YTW using substances during periods of substance use. Yet, these findings should caution researchers against simplistic generalizations as these associations differ across substance and partnership types. Efforts to promote the health of MSM-YTW who use substances should carefully consider this complexity as interventions accounting for the unique cultural context of substance use in these populations are most likely to be successful.

The relationship between age and sex partner counts during the mpox outbreak in the UK, 2022

BACKGROUND

Understanding the dynamics of an infectious disease outbreak linked to sexual activity requires valid expectations of likely counts of unique sex partners during the infectious period. Typically, age is the key demographic trait linked to expected partner count, with many transmission models removing adults from the sexually active pool abruptly at a pre-specified age threshold. Modelling the rate of decline in partner counts with age would benefit from a better description of empirical evidence.

METHODS

During the 2022 mpox epidemic in the UK, we asked individuals about their partner counts in the preceding three weeks, which is about the same as usual infectious period for persons with active mpox. We used negative binomial regression (all responses) and Weibull regression (non-zero responses) to analyse the relationship between age and partner counts, adjusted for other demographic data (such as education level and occupation), sub-dividing by three types of respondent: men who have sex with men (MSM), men who have sex with women, and women who have sex with men.

RESULTS

Most respondents had zero or one recent partner, all distributions were skewed. There was a relatively linear declining relationship between age and partner counts for heterosexual partnership groups, but a peak in partner counts and concurrency for MSMs in middle age years (age 35-54), especially for MSM who seemed to be in a highly sexually active subgroup.

CONCLUSION

Useful data were collected that can be used to describe sex partner counts during the British mpox epidemic and that show distinctive partner count relationships with age, dependent on partnership type.

Behavioral aspects and the transmission of Monkeypox: A novel approach to determine the probability of transmission for sexually transmissible diseases

Motivated by the 2022 worldwide Monkeypox (MPox) outbreak, a compartmental model is proposed to predict the evolution of the disease. Numerous models have been proposed for infectious diseases so far, although the number of variables makes it difficult to establish causation relations between individual factors and transmission rates. In order to evaluate the reaction of susceptible people to avoid infection during the outbreak, the rate of transmission is modeled through a unique phenomenological probabilistic approach, allowing the expression of the rate of generation of new cases in terms of two characteristics of the susceptible group: the frequency of sexual encounters and the probability of transmission given that there is a sexual encounter. Transmission rates are obtained and compared for the U.S. and several other countries. Results show reductions of up to 71% in the transmissibility parameter, which may be combined with variations in the frequency of sexual encounters (obtained through behavioral research) to determine the changes in the probability of transmission during an outbreak in a much more convenient way than current alternatives. This framework presents a valuable tool to health authorities in the understanding of future sexually transmissible disease outbreaks.

Racial Differences of Psychosocial Characteristics, HIV Risk-Taking and HIV Prevention Uptake between Men Who Have Sex with Men Only and Men Who Have Sex with Men and Women: A Community-Based Study in Two US Cities

Bisexual behavior preference plays an important role in shaping HIV risks among men who have sex with men (MSM), yet few studies have examined the racial differences in the patterns of sexual risk and HIV prevention uptake between men who have sex with men and women (MSMW) and men who have sex with men only (MSMO). We conducted a community-based study to identify and compare psychosocial characteristics, sexual risks, HIV testing frequency, and pre-exposure prophylaxis (PrEP) engagement between Black and White MSMW and MSMO in two US cities. Findings indicate that White MSMW were most likely to engage in HIV risk-taking behaviors (e.g., alcohol/drug use before sex, condomless/group sex), while Black MSMW were least likely to recently test for HIV or report awareness (aPR: 0.32, 95% CI: 0.17-0.61), willingness (aPR: 0.58, 95% CI: 0.30-0.98), and use (aPR: 0.59, 95% CI: 0.31-0.93) of PrEP. Findings from our study supplement salient information for designing culturally tailored HIV prevention interventions for specific MSM subgroups in the US.

Assessing the Underestimation of HIV Risk Infection among Young Men Who Have Sex with Men in Argentina

The aim of this study is to describe the discordance between the self-perceived risk and actual risk of HIV among young men who have sex with men (YMSM) and its associated factors. An online, cross-sectional study was conducted with 405 men recruited from an Argentinian NGO in 2017. Risk discordance (RD) was defined as the expression of the underestimation of risk, that is, as a lower self-perception of HIV risk, as measured with the Perceived Risk of HIV Scale, than the current risk of HIV infection, as measured by the HIV Incidence Risk Index. Multivariate logistic regression models were used to analyze the associations between the RD and the explanatory variables. High HIV risk was detected in 251 (62%), while 106 (26.2%) showed high self-perceived risk. RD was found in 230 (56.8%) YMSM. The predictors that increased RD were consistent condom use with casual partners (aOR = 3.8 [CI 95:1.5-11.0]), the use of Growler to meet partners (aOR = 10.38 [CI 95:161-121.94]), frequenting gay bars (aOR = 1.9 [95% CI:1.1-3.5]) and using LSD (aOR = 5.44 [CI 95:1.32-30.29]). Underestimation of HIV risk in YMSM is associated with standard HIV risk behavior and modulated by psychosocial aspects. Thus, prevention campaigns aimed at YMSM should include these factors, even though clinical practice does not. Health professionals should reconsider adapting their instruments to measure the risk of HIV in YMSM. It is unknown what score should be used for targeting high-risk YMSM, so more research is needed to fill this gap. Further research is needed to assess what score should be used for targeting high-risk in YMSM.

Sexual Behavior Transition and Acute and Early HIV Infection Among Men Who Have Sex With Men: Evidence from an Open Cohort in China, 2011-2019

The present study examined how sexual behaviors transit over time among men who have sex with men (MSM) and whether these transitions were associated with acute and early HIV (AEH) infection. An open cohort study was conducted using snowball sampling to recruit MSM via physical venues and Internet venues from 2011 to 2019, in China. Cox models were used to estimate the correlates of risk factors and AEH infection. We used Latent Transition Analysis (LTA) to describe behavioral profile and explore latent behavioral "trans-phenotypes," then examined the effect between different "trans-phenotypes" and AEH infection risk and explored the effect of characteristics as possible predictors of sexual behavior transition. Of 6502 MSM, a total of 1974 individuals with negative human immunodeficiency virus (HIV) tests at baseline and at least 2 visit records were included in the final analysis from 2011 to 2019. During an average 1.84 years of follow-up, 64 AEH infections were documented. In the multivariable Cox model, the association between condom use in last anal sex (HR: 0.095, 0.038-0.205), fewer sexual partners (HR: 0.375, 0.205-0.712), low frequency of condom use (HR: 3.592, 1.186-11.272), and AEH acquisition were found. The percentage of MSM with "maintain/develop safety-profile," "consistent risky-profile," and "safety-profile to risky-profile" were 52.48, 40.17, and 7.35%, respectively. Compared with "maintain\develop safety-profile," "consistent or develop risky-profile" had an increasing likelihood of AEH infection. Meanwhile, male sex workers (MSWs) or older MSM were more likely to consist or transit in "risky-profile." Having middle education is a risk factor to transit in "risky-profile" for MSM with "safety-profile" at baseline. In addition, MSM who accept health services in the past year engaged in higher proportion of developing safety-profile. Approximately half of MSM maintain or develop risky behavior with the increasing likelihood of AEH acquisition in China, which suggested that targeted and intensive interventions should be prioritized to maintain safety-profile. Clinical Trial Number: ChiCTR2000039500.

Temporal Variation in One-Time Partnership Rates Among Young Men Who Have Sex With Men and Transgender Women

BACKGROUND

Volatility in sexual contact rates has been recognized as an important factor influencing HIV transmission dynamics. One-time partnerships may be particularly important given the potential to quickly accumulate large number of contacts. Yet, empirical data documenting individual variation in contact rates remain rare. This study provides much needed data on temporal variation in one-time partners to better understand behavioral dynamics and improve the accuracy of transmission models.

METHODS

Data for this study were obtained from a longitudinal cohort study of young men who have sex with men and transgender women in Chicago. Participants provided sexual network data every 6 months for 2 years. A series of random effects models examined variation in one-time partnership rates and disaggregated within and between associations of exposure variables. Exposure variables included prior number of one-time partners, number of casual partners, and having a main partner.

RESULTS

Results indicated substantial between-person and within-person variation in one-time partners. Casual partnerships were positively associated and main partnerships negatively associated with one-time partnership rates. There remained a small positive association between prior one-time partnerships and the current number of one-time partnerships.

CONCLUSIONS

Despite the preponderance of a low number of one-time partners, substantial variation in one-time partnership rates exists among young men who have sex with men and transgender women. Accordingly, focusing on high contact rate individuals alone may be insufficient to identify periods of highest risk. Future studies should use these estimates to more accurately model how volatility impacts HIV transmission and better understand how this variation influences intervention effectiveness.

Factors related to condomless anal intercourse between men who have sex with men: results from a European bio-behavioural survey

Background

Relationship status is an important factor associated with condomless anal intercourse (CAI) amongst men who have sex with men (MSM).

Methods

A multi-centre bio-behavioural survey with MSM was conducted in 13 European cities (n = 4901) exploring factors associated with CAI via bivariate and multivariate multilevel logistic regression analyses.

Results

Likelihood of CAI with casual partners was associated with being ‘out’ to a majority (AOR = 1.19;95% CI 1,1.42); knowing their HIV status (AOR = 1.86; 95% CI 1.25,2.76); using substances (1–2 AOR = 1.39; 95% CI 1.16,1.63, 2+ AOR = 1.81; 95% CI 1.35,2.42); being older (AOR = 0.98; 95% CI 0.97,0.99); successful sero-communication (AOR = 0.79; 95% CI 0.67,0.94); and, not having a recent HIV test (AOR = 0.78; 95% CI 0.66,0.92). CAI with steady partners was associated with successful sero-communication (AOR = 2.72; 95% CI 2.72,3.66); not having a recent HIV test (AOR = 1.26; 95% CI 1.09,1.46), and; being older (AOR = 0.99; 95% CI 0.98,0.99).

Conclusions

Understandings of partner type and/or relationship status in relation to CAI amongst MSM can potentially play an important role in the development of culturally appropriate HIV/STI prevention and risk-reduction efforts targeting at-risk MSM. Our results speak to the need to consider segmented and tailored public health and health promotion initiatives for MSM with differing CAI behaviours and relationship profiles.

Sexual network and condom use among male migrants in the context of China's gender imbalance

In the context of China's gender imbalance, this study addresses the characteristics of sexual networks and their association with condom use in a sample of 713 male migrants (aged 28-64) who have rural hukou (household registration) in China. Descriptive statistics, univariate analyses, and multilevel random intercept models were used to investigate the characteristics of sexual networks and their associations with condom use. We found that age, marital status, type of sex partners, support (the main help given to each sex partner by the participant), type of sexual intercourse, and stability of sexual relationships were associated with condom use. The sexual networks were mainly composed of sex partners of similar age (58.46%), unmarried people (50.53%), and regular partners (49.38%). Married male migrants were more likely to use condoms with casual partners; unmarried male migrants were less likely to use condoms in emotional and stable relationships. Variation in individual factors, sex partners, and sexual relationship characteristics contribute to participation in condomless sex by male migrants. HIV prevention strategies should target unmarried male migrants and their casual sex partners by increasing their awareness of the risk of HIV transmission and the availability of free condoms.

Influence of sexual risk behaviour and STI co-infection dynamics on the evolution of HIV set point viral load in MSM

HIV viral load (VL) is an important predictor of HIV progression and transmission. Anti-retroviral therapy (ART) has been reported to reduce HIV transmission by lowering VL. However, apart from this beneficial effect, increased levels of population mean set-point viral load (SPVL), an estimator for HIV virulence, have been observed in men who have sex with men (MSM) in the decade following the introduction of ART in The Netherlands. Several studies have been devoted to explain these counter-intuitive trends in SPVL. However, to our knowledge, none of these studies has investigated an explanation in which it arises as the result of a sexually transmitted infection (STI) co-factor in detail. In this study, we adapted an event-based, individual-based model to investigate how STI co-infection and sexual risk behaviour affect the evolution of HIV SPVL in MSM before and after the introduction of ART. The results suggest that sexual risk behaviour has an effect on SPVL and indicate that more data are needed to test the effect of STI co-factors on SPVL. Furthermore, the observed trends in SPVL cannot be explained by sexual risk behaviour and STI co-factors only. We recommend to develop mathematical models including also factors related to viral evolution as reported earlier in the literature. However, this requires more complex models, and the collection of more data for parameter estimation than what is currently available.

HIV Care Prioritization Using Phylogenetic Branch Length

BACKGROUND

The structure of the HIV transmission networks can be dictated by just a few individuals. Public health intervention, such as ensuring people living with HIV adhere to antiretroviral therapy and remain virally suppressed, can help control the spread of the virus. However, such intervention requires using limited public health resource allocations. Determining which individuals are most at risk of transmitting HIV could allow public health officials to focus their limited resources on these individuals.

SETTING

Molecular epidemiology can help prioritize people living with HIV by patterns of transmission inferred from their sampled viral sequences. Such prioritization has been previously suggested and performed by monitoring cluster growth. In this article, we introduce Prioritization using AnCesTral edge lengths (ProACT), a phylogenetic approach for prioritizing individuals living with HIV.

METHODS

ProACT starts from a phylogeny inferred from sequence data and orders individuals according to their terminal branch length, breaking ties using ancestral branch lengths. We evaluated ProACT on a real data set of 926 HIV-1 subtype B pol data obtained in San Diego between 2005 and 2014 and a simulation data set modeling the same epidemic. Prioritization methods are compared by their ability to predict individuals who transmit most after the prioritization.

RESULTS

Across all simulation conditions and most real data sampling conditions, ProACT outperformed monitoring cluster growth for multiple metrics of prioritization efficacy.

CONCLUSION

The simple strategy used by ProACT improves the effectiveness of prioritization compared with state-of-the-art methods that rely on monitoring the growth of transmission clusters defined based on genetic distance.

Understanding the HIV Epidemic Among MSM in Baltimore: A Modeling Study Estimating the Impact of Past HIV Interventions and Who Acquired and Contributed to Infections

Supplemental Digital Content is Available in the Text.

Men who have sex with men (MSM) in the United States are disproportionately affected by HIV. We estimated the impact of past interventions and contribution of different population groups to incident MSM HIV infections.

Modelling the contribution that different sexual practices involving the oropharynx and saliva have on Neisseria gonorrhoeae infections at multiple anatomical sites in men who have sex with men

BACKGROUND

The spectrum of sexual practices that transmit Neisseria gonorrhoeae in men who have sex with men (MSM) is controversial. No studies have modelled potential Neisseria gonorrhoeae transmission when one sexual practice follows another in the same sexual encounter ('sequential sexual practices'). Our aim was to test what sequential practices were necessary to replicate the high proportion of MSM who have more than one anatomical site infected with gonorrhoea ('multisite infection').

METHODS

To test our aim, we developed eight compartmental models. We first used a baseline model (model 1) that included no sequential sexual practices. We then added three possible sequential transmission routes to model 1: (1) oral sex followed by anal sex (or vice versa) (model 2); (2) using saliva as a lubricant for penile-anal sex (model 3) and (3) oral sex followed by oral-anal sex (rimming) or vice versa (model 4). The next four models (models 5-8) used combinations of the three transmission routes.

RESULTS

The baseline model could only replicate infection at the single anatomical site and underestimated multisite infection. When we added the three transmission routes to the baseline model, oral sex, followed by anal sex or vice versa, could replicate the prevalence of multisite infection. The other two transmission routes alone or together could not replicate multisite infection without the inclusion of oral sex followed by anal sex or vice versa.

CONCLUSIONS

Our gonorrhoea model suggests sexual practices that involve oral followed by anal sex (or vice versa) may be important for explaining the high proportion of multisite infection.

The association between future time perspective and sexual behaviours in individuals attending HIV testing centres

BACKGROUND

Most European countries are still facing a high burden of sexually transmitted infections (STIs) cases each year. Available literature has found associations between time preference, i.e. the relative weight given by individuals to future outcomes compared to present ones, and various health behaviours such as tobacco or alcohol consumption, vaccination or participation in cancer screening programmes. Our objective is to investigate the role of future preference in risky sexual behaviours.

METHODS

We conducted a cross-sectional study using self-administered questionnaires in three HIV testing centres in Paris. We collected data on sexual behaviours, risk perceptions, risk attitude, future preference (Considerations of Future Consequences scale) and socioeconomic and demographic variables. Full data for variables used in regression analyses were available for 1090 respondents. We study factors associated with condom use at the first sexual encounter, with the frequency of condom use and with the number of sexual partners.

RESULTS

In the full sample, future preference is positively correlated with both measures of condom use while it is negatively correlated with the number of sexual partners. Decomposing the analysis by risk group, our results indicate that future preference has more impact on sexual behaviours, especially condom use, among men who have sex with men compared to heterosexual men and, to a lesser extent, compared to heterosexual women.

CONCLUSION

If future time perspective is confirmed as a determinant of safer sexual behaviours, prevention campaigns could be shifted towards greater information on short-term consequences of STIs.

Immigrant Generational Differences in Social Support and Sexual Risk Behaviors Among Men Who Have Sex With Men in Seattle, Washington

Different immigrant generations may encounter distinct sexual opportunities with implications for HIV transmission. Yet, few studies have examined how immigrant generational status is associated with sexual risk behaviors among men who have sex with men (MSM). We explored relationships between immigrant generational status, social support, and sexual risk behaviors among English-speaking MSM using data from surveys conducted in Seattle, Washington, in 2014 (n = 323). We compared the sexual risk behaviors and social support of first-generation, second-generation, and third- and higher-generation MSM, and examined whether immigrant generational status and social support were associated with sexual risk behaviors using logistic regression models. Second-generation MSM reported lower friend social support than first- or third- and higher-generation MSM (p < .05). However, immigrant generational status was not associated with sexual risk behavior outcomes, even after accounting for social support. Results suggest that differences in immigration processes such as acculturation may be more predictive of risk behaviors than generational status alone.

FAVITES: simultaneous simulation of transmission networks, phylogenetic trees and sequences

MOTIVATION

The ability to simulate epidemics as a function of model parameters allows insights that are unobtainable from real datasets. Further, reconstructing transmission networks for fast-evolving viruses like Human Immunodeficiency Virus (HIV) may have the potential to greatly enhance epidemic intervention, but transmission network reconstruction methods have been inadequately studied, largely because it is difficult to obtain 'truth' sets on which to test them and properly measure their performance.

RESULTS

We introduce FrAmework for VIral Transmission and Evolution Simulation (FAVITES), a robust framework for simulating realistic datasets for epidemics that are caused by fast-evolving pathogens like HIV. FAVITES creates a generative model to produce contact networks, transmission networks, phylogenetic trees and sequence datasets, and to add error to the data. FAVITES is designed to be extensible by dividing the generative model into modules, each of which is expressed as a fixed API that can be implemented using various models. We use FAVITES to simulate HIV datasets and study the realism of the simulated datasets. We then use the simulated data to study the impact of the increased treatment efforts on epidemiological outcomes. We also study two transmission network reconstruction methods and their effectiveness in detecting fast-growing clusters.

AVAILABILITY AND IMPLEMENTATION

FAVITES is available at https://github.com/niemasd/FAVITES, and a Docker image can be found on DockerHub (https://hub.docker.com/r/niemasd/favites).

SUPPLEMENTARY INFORMATION

Supplementary data are available at Bioinformatics online.

An Examination of Gay Couples' Motivations to Use (or Forego) Pre-exposure Prophylaxis Expressed During Couples HIV Testing and Counseling (CHTC) Sessions

While many gay couples perceive themselves to have little risk for HIV transmission, research estimates that 35-68% of new HIV infections are transmitted within main partnerships. Pre-exposure prophylaxis (PrEP) is recommended for those partnered gay and bisexual men (GBM) who engage in sex outside their primary relationship or who have an HIV-positive partner. There is reason to believe that couples' sero-status and sexual agreement will shape perceptions of PrEP's personal relevance among gay couples. The current study examined motivations for and ambivalence towards PrEP uptake reported in a sample of 67 gay couples during completion of a brief CDC-recommended prevention intervention: Couples HIV Testing and Counseling. Findings suggest that all types of couples identified some circumstances in which they would consider PrEP; however, PrEP messaging should be crafted to avoid undermining current prevention strategies or threatening the trust and legitimacy of the relationship.

Trends in Number and Composition of Sex Partners Among Men Who Have Sex With Men in the United States, National HIV Behavioral Surveillance, 2008-2014

BACKGROUND

Social and legal acceptance of long-term same-sex partnerships in the United States has increased over the past decade which may impact sexual partnering among men who have sex with men (MSM). Identifying whether and how partnering trends have evolved at a national level could improve understanding of HIV transmission and prevention among MSM partnerships.

METHODS

We used Centers for Disease Control and Prevention's National HIV Behavioral Surveillance data (2008, 2011, and 2014) to study trends in the number and partner type composition (main/casual) of male sex partners among US MSM. Changes over time were assessed in Poisson regression models with the link function tailored to the count and binary outcomes.

RESULTS

The mean total number of partners in the past year increased, while the mean number of main partners remained stable. The percentage of MSM with both main and casual partners increased, and we observed a shift from having ≥1 main and 0 casual partners to having ≥1 main and ≥2 casual partners. Condomless anal sex in the past year increased regardless of partner composition.

DISCUSSION

Findings suggest casual partnering among MSM has increased in recent years, including among those with ≥1 main partners. Both partner-based and individual prevention programs remain critical to reaching MSM.

Sociodemographic and Behavioral Factors Associated with HIV Vulnerability according to Sexual Orientation

Objective

To analyze sociodemographic and behavioral factors associated with vulnerability to HIV according to sexual orientation.

Method

This is a cross-sectional study conducted using data on 3,818 people in the city of Imperatriz, Brazil, during 2015 and 2016. The survey's questionnaires addressed sociodemographic and behavioral variables. For the data analysis, association (chi-square test) and strength of association (odds ratio) were observed. A significance level of p < 0.05 and adjustment for age and gender were taken into consideration.

Results

A substantial portion of the sample stated they were heterosexual (88.8%). These individuals demonstrated a lower chance of HIV infection (p < 0.001), sexually transmitted infections (p < 0.001), alcohol use (p < 0.001) and condom use (p < 0.001), compared to men who have sex with men and/or bisexuals. In this group, after adjusting for confounding variables, the factors associated with HIV infection were being male (p < 0.001), unmarried (p < 0.001), having completed higher education (p < 0.001) and boasting multiple sexual partners (p < 0.001).

Conclusion

Behavioral and sociodemographic factors of vulnerability to HIV are predominant among men who have sex with men and/or are bisexual.

Associations among Negative Urgency, Sensation Seeking, Alcohol Use, Self-Esteem, and Casual Sexual Behavior for College Students

Background: The present study proposed a moderated mediation model of relations among negative urgency, sensation seeking, alcohol use, self-esteem, and casual sexual behavior among college students. We hypothesized students' alcohol use would mediate a positive relation between two facets of impulsivity, negative urgency and sensation seeking, with casual sexual behavior. We also examined the influence of self-esteem on alcohol use and casual sexual behavior to determine if self-esteem may serve as a point of intervention. We hypothesized that self-esteem might moderate the relation between casual sexual behavior and alcohol use, such that students who report high alcohol use in addition to low self-esteem would engage in more casual sexual behavior than individuals who report relatively higher levels of self-esteem. Methods: Data were collected in 2015 from 413 undergraduate students at a large Northeastern public university. Structural equation modeling tested the moderated mediation model. Results: Contrary to hypotheses, the theorized model demonstrated an inadequate fit to the data when self-esteem was included. A second structural model was calculated to test alcohol use as a mediator of associations between negative urgency and sensation seeking, and casual sexual behavior. As hypothesized, students' alcohol use was found to be a mediator of the positive associations between negative urgency and casual sexual behavior and sensation seeking and casual sexual behavior. Conclusions: Findings suggest that alcohol use, negative urgency, and sensation seeking may serve as points of intervention to address casual sexual behavior, as appropriate, among college student populations.

An Electronic Pre-Exposure Prophylaxis Initiation and Maintenance Home Care System for Nonurban Young Men Who Have Sex With Men: Protocol for a Randomized Controlled Trial

BACKGROUND

Pre-exposure prophylaxis (PrEP) is highly efficacious for preventing HIV but has not yet been brought to scale among at-risk persons. In several clinical trials in urban areas, technology-based interventions have shown a positive impact on PrEP adherence. In rural and small-town areas in the United States, which often do not have geographically proximal access to PrEP providers, additional support may be needed. This may be particularly true for younger persons who are more likely to face multiple barriers to accessing PrEP services. Home-based care, accomplished through a tailored mobile phone app, specimen self-collection (SSC), and interactive video consultations, could increase both PrEP initiation and persistence in care.

OBJECTIVE

The goal of this study is to assess the initiation and persistence in PrEP care for those randomized to a home-care intervention (electronic PrEP, ePrEP) relative to those assigned to the standard of care (control) condition. We will conduct additional assessments, including quantitative and qualitative analyses, to contextualize trial results and facilitate scale-up.

METHODS

This 2-arm, randomized controlled trial will enroll young men who have sex with men (YMSM) aged between 18 and 24 years from rural areas of Georgia, Mississippi, and North Carolina. The trial will seek to recruit a diverse sample, targeting 50% participation among highly impacted groups of black or Latino men who have sex with men. Intervention participants will receive a study app that incorporates a messaging platform, a scheduling and milestone-based tracking system for PrEP care progress, electronic behavioral surveys, and interactive video consultations with a clinician. Complemented by SSC kits mailed to laboratories for standard PrEP-related monitoring, the ePrEP system will allow participants to access PrEP care without leaving their homes. YMSM randomized to the control condition will receive a listing of nearest local PrEP providers to receive standard PrEP care. Both groups will complete quarterly electronic surveys. The primary outcome, assessed at 6 and 12 months after randomization, will be the difference in the proportion of intervention versus control participants that achieve protective levels of the active metabolite of oral PrEP (tenofovir diphosphate in dried blood spots).

RESULTS

Enrollment will begin in May 2019, with study completion in 2022.

CONCLUSIONS

This trial will determine whether home PrEP care provided through an app-based platform is an efficacious means of expanding access to PrEP care for a diverse group of YMSM in rural and small-town areas of the United States.

TRIAL REGISTRATION

ClinicalTrials.gov NCT03729570; https://clinicaltrials.gov/ct2/show/NCT03729570 (Archived by WebCite at http://www.webcitation.org/78RE2Qizf).

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

PRR1-10.2196/13982.

Sexual Partner Characteristics, Relationship Type, and HIV Risk Among a Community Venue-based Sample of Urban Adolescent and Young Adult Men Who Have Sex with Men

Few studies have examined sexual partnerships and HIV risk in diverse samples of African American/black and Hispanic/Latino adolescent and young adult men who have sex with men (YMSM), a group that have a high burden of HIV in the U.S. A community-venue recruitment approach was used, which identified significant differences in HIV risk by sexual partner type among 1215 YMSM. Those with casual partners had a higher number of sexual partners, had more STIs, and were more likely to engage in transactional sex, to use alcohol, marijuana, or other substances compared with those with main partners only. Among those with female sexual partners, many used condoms "every time" when engaging in vaginal sex with casual partners, but a sizeable proportion "never/rarely" used condoms with their main partners. Our findings demonstrate a need for tailored HIV prevention education and counseling with necessary skills regarding consistent and correct condom use with all sexual partnerships.

A Cost Analysis of Gyrase A Testing and Targeted Ciprofloxacin Therapy Versus Recommended 2-Drug Therapy for Neisseria gonorrhoeae Infection

BACKGROUND

Novel approaches to combating drug-resistant Neisseria gonorrhoeae infections are urgently needed. Targeted therapy with ciprofloxacin has been made possible by a rapid assay for genotyping the gyrase A (gyrA) gene; a nonmutated gene reliably predicts susceptibility to ciprofloxacin.

METHODS

We determined the costs of running the gyrA assay, 500 mg of ciprofloxacin, 250 mg of ceftriaxone injection, and 1000 mg of azithromycin. Cost estimates for gyrA testing included assay reagents and labor. Cost estimates for ceftriaxone included medication, injection, administration, supplies, and equipment. We measured the cost of using the gyrA assay and treatment based on genotype using previously collected data over a 13-month period between November 2015 and November 2016 for all N. gonorrhoeae cases diagnosed at UCLA. We subsequently developed 3 cost models, varying the frequency of testing and prevalence of N. gonorrhoeae infections with ciprofloxacin-resistant or genotype-indeterminate results. We compared those estimates with the cost of recommended 2-drug therapy (ceftriaxone and azithromycin).

RESULTS

Based on a 65.3% prevalence of cases with ciprofloxacin-resistant or genotype indeterminate N. gonorrhoeae infections when running an average of 1.7 tests per day, the per-case cost of gyrA genotyping and targeted therapy was US $197.19. The per-case cost was US $155.16 assuming a 52.6% prevalence of ciprofloxacin-resistant or genotype-indeterminate infections when running an average of 17 tests per day. The per-case cost of 2-drug therapy was US $142.75.

CONCLUSIONS

Direct costs of gyrA genotyping and targeted ciprofloxacin therapy depend on the prevalence of ciprofloxacin-resistant or genotype-indeterminate infections and testing frequency.

"Stay strong! keep ya head up! move on! it gets better!!!!": resilience processes in the healthMpowerment online intervention of young black gay, bisexual and other men who have sex with men

Overlapping stigmas related to sexual minority-, race/ethnicity-, and HIV-status pose barriers to HIV prevention and care and the creation of supportive social networks for young, Black, gay, bisexual, and other men who have sex with men (GBMSM). A risk-based approach to addressing the HIV epidemic focuses on what is lacking and reinforces negative stereotypes about already-marginalized populations. In contrast, a strengths-based approach builds on Black GBMSM’s existing strengths, recognizing the remarkable ways in which they are overcoming barriers to HIV prevention and care. HealthMpowerment (HMP) is an online, mobile phone optimized intervention that aimed to reduce condomless anal intercourse and foster community among young Black GBMSM (age 18–30). Applying a resilience framework, we analyzed 322 conversations contributed by 48 HMP participants (22/48 living with HIV) on the intervention website. These conversations provided a unique opportunity to observe and analyze dynamic, interpersonal resilience processes shared in response to stigma, discrimination, and life challenges experienced by young Black GBMSM. We utilized an existing framework with four resilience processes and identified new subthemes that were displayed in these online interactions: (1) Exchanging social support occurred through sharing emotional and informational support. (2) Engaging in health-promoting cognitive processes appeared as reframing, self-acceptance, endorsing a positive outlook, and agency and taking responsibility for outcomes. (3) Enacting healthy behavioral practices clustered into modeling sex-positive norms, reducing the risk of acquiring or transmitting HIV, and living well with HIV. (4) Finally, empowering other gay and bisexual youth occurred through role modeling, promoting self-advocacy, and providing encouragement. Future online interventions could advance strengths-based approaches within HIV prevention and care by intentionally building on Black GBMSM’s existing resilience processes. The accessibility and anonymity of online spaces may provide a particularly powerful intervention modality for amplifying resilience among young Black GBMSM.

Sexual Identity Disclosure and Awareness of HIV Prevention Methods Among Black Men Who Have Sex With Men

Black men who have sex with men (BMSM) are disproportionately affected by the human immunodeficiency virus (HIV) epidemic, yet we know little about how HIV-negative BMSM of different sexual orientations access HIV prevention strategies. Identity development, minority stress, and disclosure theories suggest that for people of different sexual orientations, disclosure of sexual identity may be related to health behaviors. We performed a latent class analysis on a sample of 650 BMSM (Mage = 33.78, SD = 11.44) from Atlanta, Georgia, to explore whether sexual orientation, disclosure of sexual identity, and relationship status were related to HIV prevention strategies, including awareness of PrEP (pre-exposure prophylaxis) and PEP (post-exposure prophylaxis) and frequency of HIV testing. We found three distinct BMSM classes referred to as (1) closeted bisexuals, (2) sexual identity managers, and (3) gay, out, and open; all classes primarily engaged in casual sex. Classes differed in their awareness and access to HIV prevention strategies. The closeted bisexual class was least aware of and least likely to access HIV prevention. Findings have important implications for future research, namely the consideration of sexual identity and disclosure among BMSM. With this knowledge, we may be able to engage BMSM in HIV/sexually transmitted infection (STI) prevention services.

Determinants of HIV Incidence Disparities Among Young and Older Men Who Have Sex with Men in the United States

This study sought to determine why young men who have sex with men (MSM) have higher HIV incidence rates than older MSM in the United States. We developed hypotheses that may explain this disparity. Data came from peer-reviewed studies published during 1996-2016. We compared young and older MSM with respect to behavioral, clinical, psychosocial, and structural factors that promote HIV vulnerability. Compared with older MSM, young MSM were more likely to have HIV-discordant condomless receptive intercourse. Young MSM also were more likely to have "any" sexually transmitted infection and gonorrhea. Among HIV-positive MSM, young MSM were less likely to be virally suppressed, use antiretroviral therapy, and be aware of their infection. Moreover, young MSM were more likely than older MSM to experience depression, polysubstance use, low income, decreased health care access, and early ages of sexual expression. These factors likely converge to exacerbate age-associated HIV incidence disparities among MSM.

App-Based Sexual Partner Seeking and Sexually Transmitted Infection Outcomes: A Cross-Sectional Study of HIV-Negative Men Who Have Sex With Men Attending a Sexually Transmitted Infection Clinic in Los Angeles, California

BACKGROUND

Gay, bisexual, and other men who have sex with men (MSM) face higher rates of sexually transmitted infections (STIs) compared with the general population. The association between venues where sexual partners are met and STI transmission is dynamic and poorly understood, especially among those who use geosocial networking (GSN) apps. This study aimed to determine whether there is a difference in STI incidence between MSM who met their last sexual partner through a GSN app and MSM who met their last partner via other venues.

METHODS

Data were analyzed from HIV-negative MSM attending the Los Angeles LBGT Center between August 2015 and July 2016 (n = 9499). Logistic regression models were used to investigate the relationship between STI incidence and whether or not an individual met his last partner through a GSN app.

RESULTS

No relationship was detected between STI incidence and whether one's last sexual partner was met via GSN app. However, an association was detected between STI incidence and having used GSN apps to meet sexual partners in the past 3 months. A dose-response relationship was observed between the number of venues used to meet partners and testing positive for any STI (adjusted odds ratio, 1.08; 95% confidence interval, 1.02-1.14).

CONCLUSIONS

The relationship between how people meet sexual partners and STI acquisition is much more nuanced than previously thought. Geosocial networking apps do not inherently expose users to high-risk reservoirs of STIs, but further understanding of the complexity of sexual networks and networking methods is warranted, given increasing rates of STIs.

Sexual risk behaviour trajectories among MSM at risk for HIV in Amsterdam, the Netherlands

OBJECTIVE

Sexual risk behaviour changes during a person's life course. Insights in sexual risk behaviour trajectories of MSM may provide starting points for the timing of HIV prevention methods. We aimed to study longitudinal trajectories of sexual risk behaviour predictive of HIV acquisition from sexual debut onwards.

DESIGN

A longitudinal study among 815 HIV-negative participants of the Amsterdam Cohort Studies (ACS) who completed extensive questionnaires about their sexual behaviour every 6 months between 2007 and 2017.

METHODS

A comprehensive behavioural risk score predictive of HIV seroconversion was developed. On the basis of this risk score, linear trajectories of sexual risk behaviour and MSM group membership were estimated using latent class growth mixture modelling. Associations between longitudinal trajectories and demographic and psychosocial factors were examined.

RESULTS

Three trajectories of sexual risk behaviour were identified, which were labelled Low risk (90.3% of the sample), Falling high risk (6.5%) and Rising high risk (3.3%). MSM following the Falling high risk (20.5%) and Rising high risk (25.0%) trajectories were more likely to acquire HIV during follow-up. The Falling high risk trajectory was associated with younger age at sexual debut, fewer steady partnerships and high percentages of substance use. The Rising high-risk trajectory was associated with increasing percentages of substance use over time.

CONCLUSION

MSM follow different trajectories of changing sexual risk behaviour over time. Early identification of MSM following a trajectory of falling or rising high-risk behaviour and adequate timing of individual-based preventive interventions may reduce HIV transmission.

Associations between sexual partner number and HIV risk behaviors: implications for HIV prevention efforts in a Treatment as Prevention (TasP) environment

Previous research indicates that gay and bisexual men (GBM) have significantly more sexual partners than same-aged heterosexual men and women. As a result, some HIV intervention programs have focused on partner reduction. However, new research findings question the relevance of sexual partner number as a sexual risk measure for GBM given Treatment as Prevention (TasP) programs and new seroadaptive strategies which have led to lower GBM community viral load and new HIV prevention behaviors. To assess if sexual partner number continues to remain an important measure of sexual risk for GBM living in a city that actively promotes TasP as provincial policy, we analysed cross-sectional data from 719 GBM recruited through respondent-driven sampling in Vancouver, Canada. Multivariable negative binomial regression analysis showed that partner number was significantly associated with previously identified HIV risk factors including condomless anal intercourse with serodiscordant and/or unknown serostatus partners, using sex toys, attending group sex events, receiving money for sex, and sex drug use. These results indicate that sexual partner number remains an important proximate HIV risk measure. However, more nuanced measures of HIV treatment status and greater understanding of the possible causes of increased partner number among GBM are needed.

Age differences in sexual risk behaviors and related factors among people living with HIV in Guangxi, China

Sexual risk behaviors by people living with HIV (PLHIV) can result in secondary HIV transmission and other health problems. Given the dearth of research on age differences in sexual behaviors among PLHIV, the objective of the study is to compare sexual risk behaviors and related factors among PLHIV by age groups. Data used in the current study were derived from a cross-sectional survey conducted from 2012 to 2013 in Guangxi, China. PLHIV were selected randomly from 12 sites with the largest number of HIV/AIDS cases. The 2,987 PLHIV completing the survey were included in the study. Participants were asked about key sociodemographic characteristics, health condition, same-sex behavior, and sexual risk behaviors (number of sex partners, condom use consistency, and change in condom use after HIV diagnosis). Univariate logistic regression analyses were conducted to evaluate associations of sexual risk behaviors with age and other factors. Those variables with a p-value of less than 0.2 were entered into multivariate logistic regression models. All statistical analyses were conducted using SAS 9.4. Differences in sexual risk behaviors across age groups were observed. Compared with their younger counterparts, who were ≥ 50 years of age were more likely to have multiple partners, use condoms inconsistently, and use condoms less than before HIV diagnosis. Moreover, lower education attainment, being in the lowest or highest category of income, having a sero-concordant or sero-unknown steady partner or no steady partner, and having contracted HIV from steady or casual/commercial partners, or through injection drug use appeared to be predictive of at least one of the sexual risk behaviors examined in the study. The findings call for HIV prevention interventions to be tailored to different age groups. The interventions that can help reduce unprotected sex among older PLHIV are urgently needed.

The Effect of PrEP on HIV Incidence Among Men Who Have Sex With Men in the Context of Condom Use, Treatment as Prevention, and Seroadaptive Practices

BACKGROUND

HIV preexposure prophylaxis (PrEP) is an effective tool in preventing HIV infection among high-risk men who have sex with men (MSM). It is unknown how effective PrEP is in the context of other implemented HIV prevention strategies, including condom use, seroadaption, and treatment as prevention (TasP). We evaluate the impact of increasing uptake of PrEP in conjunction with established prevention strategies on HIV incidence in a high-risk population of MSM through simulation.

METHODS

Agent-based simulation models representing the sexual behavior of high-risk, urban MSM in the United States over the period of 1 year were used to evaluate the effect of PrEP on HIV infection rates. Simulations included data for 10,000 MSM and compared increasing rates of PrEP uptake under 8 prevention paradigms: no additional strategies, TasP, condom use, seroadaptive behavior, and combinations thereof.

RESULTS

We observed a mean of 103.2 infections per 10,000 MSM in the absence of any prevention method. PrEP uptake at 25% without any additional prevention strategies prevented 30.7% of infections. In the absence of PrEP, TasP, condom use, and seroadaptive behavior independently prevented 27.1%, 48.8%, and 37.7% of infections, respectively, and together prevented 72.2%. The addition of PrEP to the 3 aforementioned prevention methods, at 25% uptake, prevented an additional 5.0% of infections.

CONCLUSIONS

To achieve a 25% reduction in HIV infections by 2020, HIV prevention efforts should focus on significantly scaling up access to PrEP in addition to HIV testing, access to antiretroviral therapy, and promoting condom use.

Racial Differences in Partnership Attributes, Typologies, and Risk Behaviors Among Men Who Have Sex With Men in Atlanta, Georgia

The role of main partnerships in shaping HIV transmission dynamics among men who have sex with men (MSM) has gained recognition in recent studies, but there is little evidence that existing definitions of partnership type are accurate or have consistent meaning for all men. Using data collected from 2011 to 2013 on 693 partnerships described by 193 Black and White MSM in Atlanta, GA, partnership attributes and risk behaviors were examined and compared by race, stratified in two ways: (1) by commonly used definitions of partnerships as "main" or "casual" and (2) by a new data-driven partnership typology identified through latent class analysis (LCA). Racial differences were analyzed using chi-square, Fisher's exact, and Wilcoxon-Mann-Whitney tests. Black participants were less likely to report condomless anal sex (CAS) within partnerships they labeled as main, yet they were also less likely to describe these partnerships as "primary" on a parallel question. In contrast, within strata defined by the LCA-derived typology, most partnership attributes were comparable and the likelihood of CAS was equivalent by race. These findings suggest that classification of partnerships as main or casual does not accurately capture the partnership patterns of MSM, resulting in differential misclassification by race. Future studies and interventions should refine and utilize more evidence-based typologies.

Expanded antiretroviral treatment, sexual networks, and condom use: Treatment as prevention unlikely to succeed without partner reduction among men who have sex with men in China

Background

To project the impact of partner reduction on preventing new HIV infections among men who have sex with men (MSM) under varying conditions of enhanced HIV testing and treatment (T&T) and condom use in Beijing, China.

Methods and findings

A complex network model was fitted to predict the number of new HIV infections averted from 2014 to 2023 under four scenarios of sexual behavior risk reduction (S)—S1: Male sexual partners decrease (reduced by a random value m from 1–50) while condom use increases (risk constant p is a random value between 0.2 and 1]); S2: Both sexual partners and condom use decrease (m 1, 50; p 1, 1.8); S3: Sexual partners reduce (m 1, 10) while condom use increases or decreases (p 0.2, 1.8); S4: Only MSM with ≥100 male sexual partners reduce their partners (m 1, 50) while condom use increases (p 0.2, 1).

HIV prevalence will reach 23.2% by 2023 among Beijing MSM if T&T remains at the 2013 level. The three most influential factors are: T&T coverage; partner reduction (m); and the background risk (p). Under scenarios 1–4 of sexual behavioral changes with enhanced T&T interventions, the cumulative HIV new infections prevented over the 10 years will be 46.8% for S1 (interquartile range [IQR] 32.4%, 60.1%); 29.7% for S2 (IQR 18.0%, 41.4%), 23.2% for S3 (IQR 12.2%, 37.0%) and 11.6% for S4 (IQR 4.0%, 26.6%), respectively. The reproduction number R₀ could drop below 1 if there were a substantial reduction of male sexual partners and/or expanded condom use.

Conclusion

Partner reduction is a vital factor within HIV combination interventions to reduce HIV incidence among Beijing MSM, with substantial additional benefits derived from condom use. T&T without substantial partner reduction and increased condom use is less promising unless its implementation were extremely (and improbably) efficient.

Influence of concurrency, partner choice, and viral suppression on racial disparity in the prevalence of HIV infected women

In 1992, Watts and May introduced a simple dynamical systems model of the spread of HIV based on disease transmission per partnership including the length of partnership duration. This model allowed for the treatment of concurrent partnerships, although it was hampered by the assumption of an important latent phase which generated a non-autonomous system. Subsequent models including concurrency have been based on networks, Monte Carlo, and stochastic simulations which lose a qualitative understanding of the effects of concurrency. We present a new autonomous deterministic model of the effect of concurrent sexual partnerships that allows for an analytical study of disease transmission. We incorporate the effect of concurrency through the newly derived force of infection term in a mathematical model of the transmission of HIV through sexual contact in a population stratified by sexual behavior and race/ethnicity. The model also includes variations in population mixing (partner choice) and non-uniform Highly Active Anti-Retroviral Treatment (HAART) leading to viral suppression. We use this mathematical model to understand the non-uniform spread of HIV in women who were infected through heterosexual contact. In addition, an analytical study shows the importance of continued condom use in virally suppressed MSM. Numerical simulations of the reproduction number as a function of concurrency, viral suppression level, and mixing show a reservoir of disease present in both heterosexual and MSM populations. Statistical analysis of parameter values show that viral suppression level, mixing and progression to AIDS without viral suppression have a strong correlation (either positive or negative) with the number of HIV positive women. Concurrency and assortative mixing are shown to be essential to reproduce infection levels in women, as reported by 2010 data from the Center for Disease Control (CDC).

Patterns of Drug Use and Drug-related Hospital Admissions in HIV-Positive and -Negative Gay and Bisexual Men

We aimed to compare rates of illicit drug-related hospitalisations in HIV-negative (HIV-ve) (n = 1325) and HIV-positive (HIV+ve) (n = 557) gay and bisexual men (GBM) with rates seen in the general male population and to examine the association between self-reported illicit drug use and drug-related hospitalisation. Participants were asked how often they used a range of illicit drugs in the previous 6 months at annual interviews. Drug-related hospital admissions were defined as hospital admissions for mental or behavioural disorders due to illicit drug use (ICD 10: F11-16, F18, F19), drug poisoning (T40-T45, T50) or toxic effect of gases (T53, T59, T65). Drug-related hospitalisations were 4.8 times higher in the HIV-ve cohort [SIR 4.75 (95 % CI 3.30-6.91)] and 3.5 times higher in the HIV+ve cohort [SIR 3.51 (1.92-5.88)] compared with the general population. Periods of weekly drug use [IRR 1.86 (1.01-3.46)], poly-drug use [IRR 2.17 (1.07-4.38)] and cannabis use [low use-IRR 1.95 (1.01-3.77), high use-IRR 2.58 (1.29-5.16)] were associated with drug-related hospitalisation in both cohorts, as was being a consistently high meth/amphetamine user throughout follow-up [IRR 3.24 (1.07-9.83)] and being an inconsistent or consistent injecting drug user throughout follow-up [IRR 3.94 (1.61-9.66), IRR 4.43(1.04-18.76), respectively]. Other risk factors for drug-related hospitalisation indicated the likelihood of comorbid drug and mental health issues in GBM hospitalised for drug use.

Progression and Transmission of HIV/AIDS (PATH 2.0)

BACKGROUND

HIV transmission is the result of complex dynamics in the risk behaviors, partnership choices, disease stage and position along the HIV care continuum-individual characteristics that themselves can change over time. Capturing these dynamics and simulating transmissions to understand the chief sources of transmission remain important for prevention.

METHODS

The Progression and Transmission of HIV/AIDS (PATH 2.0) is an agent-based model of a sample of 10,000 people living with HIV (PLWH), who represent all men who have sex with men (MSM) and heterosexuals living with HIV in the U.S.A. Persons uninfected were modeled as populations, stratified by risk and gender. The model included detailed individual-level data from several large national surveillance databases. The outcomes focused on average annual transmission rates from 2008 through 2011 by disease stage, HIV care continuum, and sexual risk group.

RESULTS

The relative risk of transmission of those in the acute phase was nine-times [5^th and 95^th percentile simulation interval (SI): 7, 12] that of those in the non-acute phase, although, on average, those with acute infections comprised 1% of all PLWH. The relative risk of transmission was 24- to 50-times as high for those in the non-acute phase who had not achieved viral load suppression as compared with those who had. The relative risk of transmission among MSM was 3.2-times [SI: 2.7, 4.0] that of heterosexuals. Men who have sex with men and women generated 46% of sexually acquired transmissions among heterosexuals.

CONCLUSIONS

The model results support a continued focus on early diagnosis, treatment and adherence to ART, with an emphasis on prevention efforts for MSM, a subgroup of whom appear to play a role in transmission to heterosexuals.

An analysis of baseline data from the PROUD study: an open-label randomised trial of pre-exposure prophylaxis

Background

Pre-exposure prophylaxis (PrEP) has proven biological efficacy to reduce the sexual acquisition of the human immunodeficiency virus (HIV). The PROUD study found that PrEP conferred higher protection than in placebo-controlled trials, reducing HIV incidence by 86 % in a population with seven-fold higher HIV incidence than expected. We present the baseline characteristics of the PROUD study population and place the findings in the context of national sexual health clinic data.

Methods

The PROUD study was designed to explore the real-world effectiveness of PrEP (tenofovir-emtricitabine) by randomising HIV-negative gay and other men who have sex with men (GMSM) to receive open-label PrEP immediately or after a deferral period of 12 months. At enrolment, participants self-completed two baseline questionnaires collecting information on demographics, sexual behaviour and lifestyle in the last 30 and 90 days. These data were compared to data from HIV-negative GMSM attending sexual health clinics in 2013, collated by Public Health England using the genitourinary medicine clinic activity database (GUMCAD).

Results

The median age of participants was 35 (IQR: 29–43). Typically participants were white (81 %), educated at a university level (61 %) and in full-time employment (72 %). Of all participants, 217 (40 %) were born outside the UK. A sexually transmitted infection (STI) was reported to have been diagnosed in the previous 12 months in 330/515 (64 %) and 473/544 (87 %) participants reported ever having being diagnosed with an STI. At enrolment, 47/280 (17 %) participants were diagnosed with an STI. Participants reported a median (IQR) of 10 (5–20) partners in the last 90 days, a median (IQR) of 2 (1–5) were condomless sex acts where the participant was receptive and 2 (1–6) were condomless where the participant was insertive. Post-exposure prophylaxis had been prescribed to 184 (34 %) participants in the past 12 months. The number of STI diagnoses was high compared to those reported in GUMCAD attendees.

Conclusions

The PROUD study population are at substantially higher risk of acquiring HIV infection sexually than the overall population of GMSM attending sexual health clinics in England. These findings contribute to explaining the extraordinary HIV incidence rate during follow-up and demonstrate that, despite broad eligibility criteria, the population interested in PrEP was highly selective.

Trial registration

Current Controlled TrialsISRCTN94465371. Date of registration: 28 February 2013.

Electronic supplementary material

The online version of this article (doi:10.1186/s13063-016-1286-4) contains supplementary material, which is available to authorized users.

Hypersexual, Sexually Compulsive, or Just Highly Sexually Active? Investigating Three Distinct Groups of Gay and Bisexual Men and Their Profiles of HIV-Related Sexual Risk

Emerging research supports the notion that sexual compulsivity (SC) and hypersexual disorder (HD) among gay and bisexual men (GBM) might be conceptualized as comprising three groups-Neither SC nor HD; SC only, and Both SC and HD-that capture distinct levels of severity across the SC/HD continuum. We examined data from 370 highly sexually active GBM to assess how the three groups compare across a range of risk factors for HIV infection. Comparisons focused on psychosexual measures-temptation for condomless anal sex (CAS), self-efficacy for avoiding CAS, sexual excitation and inhibition-as well as reports of actual sexual behavior. Nearly half (48.9 %) of this highly sexually active sample was classified as Neither SC nor HD, 30 % as SC Only, and 21.1 % as Both SC and HD. While we found no significant differences between the three groups on reported number of male partners, anal sex acts, or anal sex acts with serodiscordant partners, the Both SC and HD group reported higher numbers of CAS acts and CAS acts with serodiscordant partners and also had a higher proportion of their anal sex acts without condoms compared to the SC Only group. Our findings support the validity of a three-group classification system of SC/HD severity in differentiating psychosexual and HIV-related sexual risk behavior outcomes in a sample of GBM who report similarly high levels of sexual activity. Notwithstanding the need for sex positive HIV prevention programs, interventions that attempt to help Both SC and HD men deal with distress and address their psychosexual needs specifically may derive HIV prevention benefits.

The impact of meeting locations for men having sex with men on the risk for bacterial sexually transmitted infections: analyses from a cross-sectional online survey

OBJECTIVES

Opportunities for men having sex with men (MSM) to meet each other have very much improved by new communication technologies. Meeting venue-based characteristics can impact how many partners are met and how much sexual risk is taken. We analysed the association between physical and virtual venues and the risk for bacterial sexually transmitted infections (bSTIs) among participants in an MSM online survey.

METHODS

Data were collected during 2013/2014 with a survey targeting MSM living in Germany. The impact of the meeting place with the last non-steady anal sex partner on diagnosis with a bSTI in the previous year was analysed using bivariate and multivariate regression analysis, taking into account self-reported HIV status, serostatus communication, condom use, partner number, age and city size.

RESULTS

The study sample consisted of 8878 respondents (7799 not diagnosed with HIV; 1079 diagnosed with HIV). Meeting partners online was most common (62% HIV-/51% HIV+), followed by sex venues (11% HIV-/25% HIV+); other venues were each reported by 2-6% of the respondents. Venue-dependent proportions reporting bSTIs in the recent year were 2-4 folds higher among men diagnosed with HIV. In multivariate analysis, HIV status was the strongest predictor for bSTIs (OR=5.0; 95% CI 2.8 to 8.7). Compared with meeting partners online, sex (OR 1.6; 95% CI 1.0 to 2.5) and social venues (OR 1.9; 95% CI 1.4 to 2.6) were associated with increased bSTI risk for men not diagnosed with HIV, but the risk when meeting partners by smartphone apps was only of borderline significance (OR 1.5; 95% CI 0.9 to 2.3). For men diagnosed with HIV, bSTI risk increased for sex venues (OR 1.5; 95% CI 1.1 to 2.1), and was lower for non-gay/other venues (OR 0.2; 95% CI 0.1 to 0.5).

CONCLUSIONS

Venues are connected to social-behavioural facets of corresponding sexual encounters, and may be important arenas for differential HIV and STI education, treatment and prevention.

HIV Serosorting, Status Disclosure, and Strategic Positioning Among Highly Sexually Active Gay and Bisexual Men

Researchers have identified harm reduction strategies that gay, bisexual, and other men who have sex with men (GBMSM) use to reduce HIV transmission--including serosorting, status disclosure, and strategic positioning. We report on patterns of these behaviors among 376 highly sexually active (i.e., 9+partners, <90 days) GBMSM: mean age of 37, 49.5% men of color, 87.8% gay identified, 57.5% college educated. We found evidence that many men engaged in serosorting, status disclosure, and strategic positioning; however, rates varied based on the participant's HIV status. HIV-positive and HIV-negative men both engaged in sex with men of similar status more often than they engaged in sex with men known to be a different HIV status (i.e., serosorting). However, HIV-negative men disclosed their HIV-status with about half of their partners, whereas HIV-positive participants disclosed with only about one-third. With regard to strategic positioning, HIV-positive participants were the receptive partner about half the time with their HIV-negative partners and with their HIV-positive partners. In contrast, strategic positioning was very common among HIV-negative participants-they rarely bottomed with HIV-positive partners, bottomed about one-third of the time with status-unknown partners, and 42% of the time (on average) with HIV-negative partners. Highly sexually active GBMSM are a critical population in which to both investigate HIV prevention strategies as well as develop effective intervention programs. Providers and clinicians might be well served to include a wide range of behavioral harm reduction strategies in addition to condom use and biomedical approaches to reduce onward HIV transmission.

The Epidemiologic and Economic Impact of Improving HIV Testing, Linkage, and Retention in Care in the United States

BACKGROUND

Recent guidelines advocate early antiretroviral therapy (ART) to decrease human immunodeficiency virus (HIV) morbidity and prevent transmission, but suboptimal engagement in care may compromise impact. We sought to determine the economic and epidemiologic impact of incomplete engagement in HIV care in the United States.

METHODS

We constructed a dynamic transmission model of HIV among US adults (aged 15-65 years) and conducted a cost-effectiveness analysis of improvements along the HIV care continuum : We evaluated enhanced HIV testing (annual for high-risk groups), increased 3-month linkage to care (to 90%), and improved retention (50% relative reduction in yearly disengagement and 50% increase in reengagement). Our primary outcomes were HIV incidence, mortality, costs and quality-adjusted life-years (QALYs).

RESULTS

Despite early ART initiation, a projected 1.39 million (95% uncertainty range [UR], 0.91-2.2 million) new HIV infections will occur at a (discounted) cost of $256 billion ($199-298 billion) over 2 decades at existing levels of HIV care engagement. Enhanced testing with increased linkage has modest epidemiologic benefits and could reduce incident HIV infections by 21% (95% UR, 13%-26%) at a cost of $65 700 per QALY gained ($44 500-111 000). By contrast, comprehensive improvements that couples enhanced testing and linkage with improved retention would reduce HIV incidence by 54% (95% UR, 37%-68%) and mortality rate by 64% (46%-78%), at a cost-effectiveness ratio of $45 300 per QALY gained ($27 800-72 300).

CONCLUSIONS

Failure to improve engagement in HIV care in the United States leads to excess infections, treatment costs, and deaths. Interventions that improve not just HIV screening but also retention in care are needed to optimize epidemiologic impact and cost-effectiveness.

Sexual Networks and HIV Risk among Black Men Who Have Sex with Men in 6 U.S. Cities

BACKGROUND

Sexual networks may place U.S. Black men who have sex with men (MSM) at increased HIV risk.

METHODS

Self-reported egocentric sexual network data from the prior six months were collected from 1,349 community-recruited Black MSM in HPTN 061, a multi-component HIV prevention intervention feasibility study. Sexual network composition, size, and density (extent to which members are having sex with one another) were compared by self-reported HIV serostatus and age of the men. GEE models assessed network and other factors associated with having a Black sex partner, having a partner with at least two age category difference (age difference between participant and partner of at least two age group categories), and having serodiscordant/serostatus unknown unprotected anal/vaginal intercourse (SDUI) in the last six months.

RESULTS

Over half had exclusively Black partners in the last six months, 46% had a partner of at least two age category difference, 87% had ≤5 partners. Nearly 90% had sex partners who were also part of their social networks. Among HIV-negative men, not having anonymous/exchange/ trade partners and lower density were associated with having a Black partner; larger sexual network size and having non-primary partners were associated with having a partner with at least two age category difference; and having anonymous/exchange/ trade partners was associated with SDUI. Among HIV-positive men, not having non-primary partners was associated with having a Black partner; no sexual network characteristics were associated with having a partner with at least two age category difference and SDUI.

CONCLUSIONS

Black MSM sexual networks were relatively small and often overlapped with the social networks. Sexual risk was associated with having non-primary partners and larger network size. Network interventions that engage the social networks of Black MSM, such as interventions utilizing peer influence, should be developed to address stable partnerships, number of partners, and serostatus disclosure.

Correlates of unprotected anal intercourse: the influence of anal sex position among men who have sex with men in Beijing, china

Understanding barriers to consistent condom use among men who have sex with men (MSM) requires consideration of the context in which risk behaviors occur. Anal sex position is one such context. This pooled cross-sectional study used survey data from 1,230 MSM and their 2,618 reported male sexual partnerships. Overall, nearly half of the participants engaged in unprotected anal intercourse (UAI) with at least one of upto three partners in the past 6 months. "Insertive" men engaged in less UAI (39 %) than "receptive" (53 %) or "versatile" (51 %) men. Regardless of sexual position, UAI was associated with cohabiting with a male or female partner and perceiving great or moderate risk of HIV from male contact at the individual level, and steady (vs. casual) partnership at the dyad level. However, early MSM anal sex debut, high number of male partners, alcohol use, receiving and buying condoms, HIV testing, and MSM sex-seeking venues were found to be only statistically significantly correlated with UAI among some but not all sexual positions, implying that interventions to increase condom use should take into account how anal sex position may influence willingness and ability to engage in safer sex. Dyad level data appear to provide additional insight into the influence of sexual positions, and should be used to complement individual data for future intervention designs.

Assessment of a new web-based sexual concurrency measurement tool for men who have sex with men

BACKGROUND

Men who have sex with men (MSM) are the most affected risk group in the United States' human immunodeficiency virus (HIV) epidemic. Sexual concurrency, the overlapping of partnerships in time, accelerates HIV transmission in populations and has been documented at high levels among MSM. However, concurrency is challenging to measure empirically and variations in assessment techniques used (primarily the date overlap and direct question approaches) and the outcomes derived from them have led to heterogeneity and questionable validity of estimates among MSM and other populations.

OBJECTIVE

The aim was to evaluate a novel Web-based and interactive partnership-timing module designed for measuring concurrency among MSM, and to compare outcomes measured by the partnership-timing module to those of typical approaches in an online study of MSM.

METHODS

In an online study of MSM aged ≥18 years, we assessed concurrency by using the direct question method and by gathering the dates of first and last sex, with enhanced programming logic, for each reported partner in the previous 6 months. From these methods, we computed multiple concurrency cumulative prevalence outcomes: direct question, day resolution / date overlap, and month resolution / date overlap including both 1-month ties and excluding ties. We additionally computed variants of the UNAIDS point prevalence outcome. The partnership-timing module was also administered. It uses an interactive month resolution calendar to improve recall and follow-up questions to resolve temporal ambiguities, combines elements of the direct question and date overlap approaches. The agreement between the partnership-timing module and other concurrency outcomes was assessed with percent agreement, kappa statistic (κ), and matched odds ratios at the individual, dyad, and triad levels of analysis.

RESULTS

Among 2737 MSM who completed the partnership section of the partnership-timing module, 41.07% (1124/2737) of individuals had concurrent partners in the previous 6 months. The partnership-timing module had the highest degree of agreement with the direct question. Agreement was lower with date overlap outcomes (agreement range 79%-81%, κ range .55-.59) and lowest with the UNAIDS outcome at 5 months before interview (65% agreement, κ=.14, 95% CI .12-.16). All agreements declined after excluding individuals with 1 sex partner (always classified as not engaging in concurrency), although the highest agreement was still observed with the direct question technique (81% agreement, κ=.59, 95% CI .55-.63). Similar patterns in agreement were observed with dyad- and triad-level outcomes.

CONCLUSIONS

The partnership-timing module showed strong concurrency detection ability and agreement with previous measures. These levels of agreement were greater than others have reported among previous measures. The partnership-timing module may be well suited to quantifying concurrency among MSM at multiple levels of analysis.

Risk of using logistic regression to illustrate exposure-response relationship of infectious diseases

Background

In most biological experiments, especially infectious disease, the exposure-response relationship is interrelated by a multitude of factors rather than many independent factors. Little is known about the suitability of ordinary, categorical exposures, and logarithmic transformation which have been presented in logistic regression models to assess the likelihood of an infectious disease as a function of a risk or exposure. This study aims to examine and compare the current approaches.

Methods

A simulated human immunodeficiency virus (HIV) population, dynamic infection data for 100,000 individuals with 1% initial prevalence and 2% infectivity, was created. Using the Monte Carlo method (computational algorithm) to repeat random sampling to obtain numerical results, linearity between log odds and exposure, and suitability in practice were examined in the three model approaches.

Results

Despite diverse population prevalence, the linearity was not satisfied between log odds and raw exposures. Logarithmic transformation of exposures improved the linearity to a certain extent, and categorical exposures satisfied the linear assumption (which was important for modelling). When the population prevalence was low (assumed < 10%), performances of the three models were significantly different. Comparing to ordinary logistic regression, the logarithmic transformation approach demonstrated better accuracy of estimation except that at the two inflection points: likelihood of infection increased from slowly to sharply, then slowly again. The approach using categorical exposures had better estimations around the real values, but the measurement was coarse due to categorization.

Conclusions

It is not suitable to directly use ordinary logistic regression to explore the exposure-response relationship of HIV as an infectious disease. This study provides some recommendations for practical implementations including: 1) utilize categorical exposure if a large sample size and low population prevalence are provided; 2) utilize a logarithmic transformed exposure if the sample size is insufficient or the population prevalence is too high (such as 30%).

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2334-14-540) contains supplementary material, which is available to authorized users.

Risk factors associated with HIV infection among male homosexuals and bisexuals followed in an open cohort study: Project Horizonte, Brazil (1994-2010)

BACKGROUND

There has recently been an increase in HIV infection rates among men who have sex with men (MSM). This study aimed at investigating risk factors associated with incident HIV infection in a MSM cohort-Project Horizonte, Belo Horizonte, Minas Gerais, Brazil.

METHODOLOGY

This is a nested case-control study in an ongoing open cohort of homosexual and bisexual men, carried out in 1994-2010, during which 1,085 volunteers were enrolled. Each HIV seroconverted volunteer (case) was compared with three randomly selected HIV negative controls, matched by admission date and age (±3 years). During follow-up, 93 volunteers seroconverted and were compared with 279 controls.

PRINCIPAL FINDINGS

The risk factors associated with HIV seroconversion were: contact with partner's blood during sexual relations (OR 3.7; 95% CI 1.2-11.6), attendance at gay saunas in search for sexual partners (OR 2.6; 95% CI 1.3-5.4), occasional intake of alcohol when flirting and engaging in sexual activity (OR 2.5; 95% CI 1.3-5.1), inconsistent use of condoms in receptive anal sex (OR 2.4; 95% CI 1.1-5.4), little interest to look up information about AIDS (OR 2.6; 95% CI 1.0-6.7) particularly in newspapers (OR 3.4; 95% CI 1.4-8.1).

CONCLUSIONS

This study shows that MSM are still engaging in risk behavior, such as unprotected anal intercourse, despite taking part in a cohort study on various preventive measures. New preventive strategies in touch with the epidemic's development and the specificities of this particular population are needed.