Impact of post-incarceration care engagement interventions on HIV transmission among young Black men who have sex with men and their sexual partners: an agent-based network modeling study

Background

Understanding the impact of incarceration on HIV transmission among Black men who have sex with men is important given their disproportionate representation among people experiencing incarceration and the potential impact of incarceration on social and sexual networks, employment, housing, and medical care. We developed an agent-based network model (ABNM) of 10,000 agents representing young Black men who have sex with men in the city of Chicago to examine the impact of varying degrees of post-incarceration care disruption and care engagement interventions following release from jail on HIV incidence.

Methods

Exponential random graph models were used to model network formation and dissolution dynamics, and network dynamics and HIV care continuum engagement were varied according to incarceration status. Hypothetical interventions to improve post-release engagement in HIV care for individuals with incarceration (e.g., enhanced case management, linkage to housing and employment services) were compared to a control scenario with no change in HIV care engagement after release.

Finding

HIV incidence at 10 years was 4.98 [95% simulation interval (SI): 4.87, 5.09 per 100 person-years (py)] in the model population overall; 5.58 (95% SI 5.38, 5.76 per 100 py) among those with history of incarceration, and 12.86 (95% SI 11.89, 13.73 per 100 py) among partners of agents recently released from incarceration. Sustained post-release HIV care for agents with HIV and experiencing recent incarceration resulted in a 46% reduction in HIV incidence among post-incarceration partners [incidence rate (IR) per 100 py = 5.72 (95% SI 5.19, 6.27) vs. 10.61 (95% SI 10.09, 11.24); incidence rate ratio (IRR) = 0.54; (95% SI 0.48, 0.60)] and a 19% reduction in HIV incidence in the population overall [(IR per 100 py = 3.89 (95% SI 3.81-3.99) vs. 4.83 (95% SI 4.73, 4.92); IRR = 0.81 (95% SI 0.78, 0.83)] compared to a scenario with no change in HIV care engagement from pre-to post-release.

Interpretation

Developing effective and scalable interventions to increase HIV care engagement among individuals experiencing recent incarceration and their sexual partners is needed to reduce HIV transmission among Black men who have sex with men.

Funding

This work was supported by the following grants from the National Institutes of Health: R01DA039934; P20 GM 130414; P30 AI 042853; P30MH058107; T32 DA 043469; U2C DA050098 and the California HIV/AIDS Research Program: OS17-LA-003; H21PC3466.

The Integration of Value Assessment and Social Network Methods for Breast Health Navigation Among African Americans

OBJECTIVES

A major strategy to reduce the impact of breast cancer (BC) among African Americans (AA) is patient navigation, defined here as individualized assistance for reducing barriers to healthcare use. The primary focus of this study was to estimate the added value of incorporating breast health promotion by navigated participants and the subsequent BC screenings that network members may obtain.

METHODS

In this study, we compared the cost-effectiveness of navigation across 2 scenarios. First, we examine the effect of navigation on AA participants (scenario 1). Second, we examine the effect of navigation on AA participants and their networks (scenario 2). We leverage data from multiple studies in South Chicago. Our primary outcome (BC screening) is intermediate, given limited available quantitative data on the long-term benefits of BC screening for AA populations.

RESULTS

When considering participant effects alone (scenario 1), the incremental cost-effectiveness ratio was $3845 per additional screening mammogram. When including participant and network effects (scenario 2), the incremental cost-effectiveness ratio was $1098 per additional screening mammogram.

CONCLUSION

Our findings suggest that inclusion of network effects can contribute to a more precise, comprehensive assessment of interventions for underserved communities.

Expanding Medicaid to Reduce Human Immunodeficiency Virus Transmission in Houston, Texas: Insights From a Modeling Study

CONTEXT

Medicaid expansion has been nationally shown to improve engagement in the human immunodeficiency virus (HIV) treatment and prevention continua, which are vital steps to stopping the HIV epidemic. New HIV infections in the United States are disproportionately concentrated among young Black men who have sex with men (YBMSM). Houston, TX, is the most populous city in the Southern United States with a racially/ethnically diverse population that is located in 1 of 11 US states that have not yet expanded Medicaid coverage as of 2021.

METHODS

An agent-based model that incorporated the sexual networks of YBMSM was used to simulate improved antiretroviral treatment and pre-exposure prophylaxis (PrEP) engagement through Medicaid expansion in Houston, TX. Analyses considered the HIV incidence (number of new infections and as a rate metric) among YBMSM over the next 10 years under Medicaid expansion as the primary outcome. Additional scenarios, involving viral suppression and PrEP uptake above the projected levels achieved under Medicaid expansion, were also simulated.

RESULTS

The baseline model projected an HIV incidence rate of 4.96 per 100 person years (py) and about 368 new annual HIV infections in the 10th year. Improved HIV treatment and prevention continua engagement under Medicaid expansion resulted in a 14.9% decline in the number of annual new HIV infections in the 10th year. Increasing viral suppression by an additional 15% and PrEP uptake by 30% resulted in a 44.0% decline in new HIV infections in the 10th year, and a 27.1% decline in cumulative infections across the 10 years of the simulated intervention.

FINDINGS

Simulation results indicate that Medicaid expansion has the potential to reduce HIV incidence among YBMSM in Houston. Achieving HIV elimination objectives, however, might require additional effective measures to increase antiretroviral treatment and PrEP uptake beyond the projected improvements under expanded Medicaid.

Impact of changes in protective behaviors and out-of-household activities by age on COVID-19 transmission and hospitalization in Chicago, Illinois

PURPOSE

Even with an efficacious vaccine, protective behaviors (social distancing, masking) are essential for preventing COVID-19 transmission and could become even more important if current or future variants evade immunity from vaccines or prior infection.

METHODS

We created an agent-based model representing the Chicago population and conducted experiments to determine the effects of varying adult out-of-household activities (OOHA), school reopening, and protective behaviors across age groups on COVID-19 transmission and hospitalizations.

RESULTS

From September-November 2020, decreasing adult protective behaviors and increasing adult OOHA both substantially impacted COVID-19 outcomes; school reopening had relatively little impact when adult protective behaviors and OOHA were maintained. As of November 1, 2020, a 50% reduction in young adult (age 18-40) protective behaviors resulted in increased latent infection prevalence per 100,000 from 15.93 (IQR 6.18, 36.23) to 40.06 (IQR 14.65, 85.21) and 19.87 (IQR 6.83, 46.83) to 47.74 (IQR 18.89, 118.77) with 15% and 45% school reopening. Increasing adult (age ≥18) OOHA from 65% to 80% of prepandemic levels resulted in increased latent infection prevalence per 100,000 from 35.18 (IQR 13.59, 75.00) to 69.84 (IQR 33.27, 145.89) and 38.17 (IQR 15.84, 91.16) to 80.02 (IQR 30.91, 186.63) with 15% and 45% school reopening. Similar patterns were observed for hospitalizations.

CONCLUSIONS

In areas without widespread vaccination coverage, interventions to maintain adherence to protective behaviors, particularly among younger adults and in out-of-household settings, remain a priority for preventing COVID-19 transmission.

Patient Navigation Can Improve Breast Cancer Outcomes among African American Women in Chicago: Insights from a Modeling Study

African American (AA) women experience much greater mortality due to breast cancer (BC) than non-Latino Whites (NLW). Clinical patient navigation is an evidence-based strategy used by healthcare institutions to improve AA women's breast cancer outcomes. While empirical research has demonstrated the potential effect of navigation interventions for individuals, the population-level impact of navigation on screening, diagnostic completion, and stage at diagnosis has not been assessed. An agent-based model (ABM), representing 50-74-year-old AA women and parameterized with locally sourced data from Chicago, is developed to simulate screening mammography, diagnostic resolution, and stage at diagnosis of cancer. The ABM simulated three counterfactual scenarios: (1) a control setting without any navigation that represents the "standard of care"; (2) a clinical navigation scenario, where agents receive navigation from hospital-affiliated staff; and (3) a setting with network navigation, where agents receive clinical navigation and/or social network navigation (i.e., receiving support from clinically navigated agents for breast cancer care). In the control setting, the mean population-level screening mammography rate was 46.3% (95% CI: 46.2%, 46.4%), the diagnostic completion rate was 80.2% (95% CI: 79.9%, 80.5%), and the mean early cancer diagnosis rate was 65.9% (95% CI: 65.1%, 66.7%). Simulation results suggest that network navigation may lead up to a 13% increase in screening completion rate, 7.8% increase in diagnostic resolution rate, and a 4.9% increase in early-stage diagnoses at the population-level. Results suggest that systems science methods can be useful in the adoption of clinical and network navigation policies to reduce breast cancer disparities.

Healthcare Predictors of Information Dissemination About Genetic Risks

Objectives

Despite the benefits of genetic counseling and testing (GCT), utilization is particularly low among African American (AA) women who exhibit breast cancer features that are common in BRCA-associated cancer. Underutilization is especially problematic for AA women who are more likely to die from breast cancer than women from any other race or ethnicity. Due to medical mistrust, fear, and stigma that can be associated with genetic services among racial/ethnic minorities, reliance on trusted social networks may be an impactful strategy to increase dissemination of knowledge about hereditary cancer risk. Informed by the social cognitive theory, the purpose of this study is to determine: 1) which AA patients diagnosed with breast cancer and with identified hereditary risk are sharing information about hereditary risk with their networks; 2) the nature of the information dissemination; and 3) if personal GCT experiences is associated with dissemination of information about hereditary risk.

Methods

Among consented participants (n = 100) that completed an interview administered using a 202-item questionnaire consisting of open- and closed-ended questions, 62 patients were identified to be at higher risk for breast cancer. Descriptive statistics, bivariable chi-square, Pearson’s exact tests, and regression analyses were conducted to examine differences in characteristics between high-risk participants who disseminated hereditary risk information and participants who did not.

Results

Among high-risk participants, 25 (40%) indicated they had disseminated information about hereditary risk to at least one member in their family/friend network and 37 (60%) had not. Receipt of both provider recommendations and receipt of GCT services was associated with greater odds of disseminating information about hereditary risk with networks, OR = 4.53, 95%CI [1.33, 15.50], p = .02.

Conclusion

Interventions that increase self-efficacy gained through additional personalized knowledge and experience gained through provider recommendations and by undergoing GCT may facilitate information dissemination among social/familial networks.

Abstract PO-208: The value of estimating spillover effects in health equity interventions: A case study to promote mammogram uptake among African American women and their social networks

Introduction: Standard economic evaluation methods may underestimate the value of health equity interventions by focusing exclusively on program costs and direct effects on participants' health. Yet, these interventions have spillover effects – wherein participants transition from being intervention recipients to becoming health advocates for their social networks. Consequently, interventions may improve the health of participants and other community members who are not directly connected with interventions. This study demonstrates the utility of incorporating spillover effects by comparing incremental cost-effectiveness ratios via a patient navigation intervention to promote mammography screening among African American (AA) women. Specifically, we compare the relative costs and cost-effectiveness when including mammography uptake of: (1) AA intervention participants (egos) only versus (2) AA intervention participants (egos) and their screening eligible social network members (alters). Methods: Our study draws from two studies: (1) an individual randomized trial to test the efficacy of patient navigation on mammography uptake (Patient Navigation in Medically Underserved Areas [PNMUA]) and (2) an observational ancillary study to test the effects of PNMUA on breast cancer survivor egos and their alters (Offering AA Survivors Increased Support [OASIS]). Overall, we used a healthcare system perspective. For 2021 cost data, we collected data from study records and expense reports. For effects data, we used: (1) medical record data for egos' mammography uptake, (2) self-report data from egos regarding their alters' mammography uptake, and (3) self-report data from alters about their own mammography uptake. We consequently computed incremental cost-effectiveness ratios (ICERs), using different data sources, to assess the impact of estimating spillover effects on economic evaluation of patient navigation. Results: Total cost of the intervention was $196,601. The greatest expense were breast cancer navigators' salaries and fringe rates ($126,745). In PNMUA, more navigated vs. non-navigated egos obtained biennial mammograms (45% vs. 39%). In terms of spillover effects, more navigation arm alters obtained biennial mammograms compared to alters in the non-navigated arm (ego self-report: n=1296 vs 949; alter self-report: n=1521 vs. 1195). Navigation had lower value when only incorporating participants' mammography uptake ($3,277 per each additional woman screened) versus when incorporating spillover effects ($2,027-$2,114 per each additional woman screened). Conclusion: Our results suggest breast cancer navigation programs may be more valuable when including spillover effects. This case study provides insight with real-world applicability into integrating spillover effects into economic evaluation. Our methods offer a new avenue for improved cost and effect estimates of health equity interventions, which may be useful for assessing future resource allocation in healthcare practice and policy.

Citation Format: Nyahne Bergeron, Veronica Fitzpatrick, Carl Asche, Karriem S. Watson, Aditya S. Khanna, Bridgette Hempstead, Elizabeth A. Calhoun, Jean McDougall, Yamilé Molina. The value of estimating spillover effects in health equity interventions: A case study to promote mammogram uptake among African American women and their social networks [abstract]. In: Proceedings of the AACR Virtual Conference: 14th AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2021 Oct 6-8. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2022;31(1 Suppl):Abstract nr PO-208.

Socio-Structural and Neighborhood Predictors of Incident Criminal Justice Involvement in a Population-Based Cohort of Young Black MSM and Transgender Women

Black men who have sex with men (MSM) and transgender women are disproportionately affected by criminal justice involvement (CJI) and HIV. This study recruited 618 young Black MSM and transgender women in Chicago, IL, using respondent-driven sampling between 2013 and 2014. Random effects logistic regression evaluated predictors of incident CJI over 18 months of follow-up. Controlling for respondent age, gender and sexual identity, spirituality (aOR 0.56, 95% CI 0.33-0.96), and presence of a mother figure (aOR 0.41, 95% CI 0.19-0.89) were protective against CJI. Economic hardship (financial or residential instability vs. neither aOR 2.23, 95% CI 1.10-4.51), two or more past episodes of CJI vs. none (aOR 2.66, 95% CI 1.40-5.66), and substance use (marijuana use vs. none aOR 2.79, 95% CI 1.23-6.34; other drug use vs. none aOR 4.49, 95% CI 1.66-12.16) were associated with CJI during follow-up. Research to identify and leverage resilience factors that can buffer the effects of socioeconomic marginalization may increase the effectiveness of interventions to address the socio-structural factors that increase the risk for CJI among Black MSM and transgender women. Given the intersection of incarceration, HIV and other STIs, and socio-structural stressors, criminal justice settings are important venues for interventions to reduce health inequities in these populations.

The potential of online social networking data for augmenting the study of high-risk personal networks among young men who have sex with men at-risk for HIV

Capturing dynamics in high-risk personal networks is essential for preventing HIV transmission. Online social networking data offer incentive to augment traditional selfreported approaches for network enumeration. To explore what online networks reveal about dynamics among high-risk associates, we examine the relationship between egocentric confidant and sex networks and personal Facebook friendship networks of a cohort of young Black men who have sex with men. Although overlap exists between self-reported and Facebook associates, the stabilities of each were unrelated. Confidants who were also Facebook friends with a respondent were, however, more likely to be retained. Thus, Facebook networks contain stable confidants.

Super protective anti-bacterial coating development with silica-titania nano core-shells

In the present study, we have developed an anti-bacterial as well as mechanically-strengthened super protective coating material, which can be used as a marine antifouling paint. In this research, silica, titania and silica-titania core-shell nanoparticles were individually prepared via sol-gel and peptization processes. The idea behind the synthesis of core-shell nanoparticles was to utilize the mechanical strength of silica and the antimicrobial property of TiO₂ together. These nanoparticles were characterized via dynamic light scattering, UV-Visible spectroscopy, X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, transmission electron microscopy and X-ray photoelectron spectroscopy. Coating formulations were developed with two types of model binders, i.e., solvent-based polyurethane and water-based poly-acrylic, containing all nanoparticles individually at various concentrations for a better comparative study. These coating formulations were applied onto mild steel for anti-bacterial testing that was performed against Escherichia coli and Bacillus. The nanoparticle concentration was varied from 1% (wt) to 6% (wt). The best anti-bacterial result was obtained with 4% (wt) of silica-titania core-shell nanoparticles prepared via the peptization process among all the nanoparticles. The scratch testing was performed successfully using an Erichsen scratch tester; the formulated PU coating passed up-to 20 N load with good adhesion, impact resistance, flexibility and has shown satisfactory anti-corrosion performance.

Sex Partner Behavior Variation Related to Network Position of and Residential Proximity to Sex Partners Among Young Black Men Who Have Sex with Men

This analysis examines how sex behaviors are influenced by a sex partner's network bridging position and the residential proximity between the two. The study sample consisted of 437 young black men who have sex with men (YBMSM) in Chicago and their sex partners (2013-2014). Dyadic analyses that clustered on individuals using generalized estimating equations (n = 1095 relationships) were conducted to assess the associations between different HIV-related sexual behaviors and the network position of and residential proximity to a partner. The odds of group sex was higher with partners who had high network bridging, regardless of how close they lived to one another. The odds of transactional sex was higher with partners who had high network bridging and lived in a different region of the city. Sex behaviors associated with an increased risk of HIV transmission were associated with the network structural position of and residential proximity to partners among YBMSM.

A modeling framework to inform preexposure prophylaxis initiation and retention scale-up in the context of 'Getting to Zero' initiatives

OBJECTIVE(S)

'Getting to Zero' (GTZ) initiatives aim to eliminate new HIV infections over a projected time frame. Increased preexposure prophylaxis (PrEP) uptake among populations with the highest HIV incidence, such as young Black MSM, is necessary to accomplish this aim. Agent-based network models (ABNMs) can help guide policymakers on strategies to increase PrEP uptake.

DESIGN

Effective PrEP implementation requires a model that incorporates the dynamics of interventions and dynamic feedbacks across multiple levels including virus, host, behavior, networks, and population. ABNMs are a powerful tool to incorporate these processes.

METHODS

An ABNM, designed for and parameterized using data for young Black MSM in Illinois, was used to compare the impact of PrEP initiation and retention interventions on HIV incidence after 10 years, consistent with GTZ timelines. Initiation interventions selected individuals in serodiscordant partnerships, or in critical sexual network positions, and compared with a controlled setting where PrEP initiators were randomly selected. Retention interventions increased the mean duration of PrEP use. A combination intervention modeled concurrent increases in PrEP initiation and retention.

RESULTS

Selecting HIV-negative individuals for PrEP initiation in serodiscordant partnerships resulted in the largest HIV incidence declines, relative to other interventions. For a given PrEP uptake level, distributing effort between increasing PrEP initiation and retention in combination was approximately as effective as increasing only one exclusively.

CONCLUSION

Simulation results indicate that expanded PrEP interventions alone may not accomplish GTZ goals within a decade, and integrated scale-up of PrEP, antiretroviral therapy, and other interventions might be necessary.

The Social Context of HIV Prevention and Care among Black Men Who Have Sex with Men in Three U.S. Cities: The Neighborhoods and Networks (N2) Cohort Study

Background: In many parts of the world, stark racial disparities in human immunodeficiency virus (HIV) prevalence, incidence, prevention, and care outcomes persist among gay, bisexual, and other men who have sex with men (MSM), with Black MSM significantly impacted in the United States (U.S.). Individual-level characteristics, including sexual behaviors and socioeconomic status, do not fully account for racial/ethnic disparities in HIV among MSM. We hypothesize that neighborhood contexts and network characteristics influence risk for HIV infection as well as HIV-related prevention and care behaviors. As such, the study design includes the use of real-time geospatial methods and in-depth assessments of multiple network typologies to investigate the impact of neighborhood and network-level factors on HIV prevention and treatment among Black MSM residing in longstanding priority HIV elimination areas in the U.S., namely Chicago, Illinois and in the Deep South (Jackson, Mississippi and New Orleans, Louisiana) (n = 450, n = 50, and n = 100, respectively). We describe the design, sampling methods, data collection, data management methods, and preliminary findings of the ongoing ‘Neighborhoods and Networks (N2) Cohort Study’. Methods/Design: N2 employs a prospective longitudinal design. The sample includes Black MSM participants in Chicago recruited via respondent-driven sampling and assessed every six months over two years of follow-up. Participants enrolled in Jackson and New Orleans are being recruited through existing health and community services and assessed every six months over one year of follow-up. Mobility within and between neighborhoods is being assessed using global positioning system (GPS) technology. Social and sexual networks among Black MSM are being studied through egocentric network inventories as well as newer methods of creating meso-level networks that involve social media (Facebook) and mobile phone contacts. Key HIV prevention outcomes such as pre-exposure prophylaxis (PrEP) care engagement, and HIV/STI (sexually transmitted infections) biomarkers will be examined at baseline and follow-up. Results: As of 31 December 2018, a total of 361 men were enrolled across all study sites: 259 in Chicago and 102 in the Deep South (75 in New Orleans and 27 in Jackson). At baseline, participants ranged in age from 17 to 65 years old (mean = 34.3, standard deviation = 5.1) with 123 men (34.1%) self-reported as HIV positive. While HIV treatment levels were similar between sites, men in the Deep South reported higher rates of adherence than men in Chicago (63.3% versus 49.4%, p = 0.03). Sexual risk profiles were mainly the same between men from different study sites, with 22.9% of men in Chicago and 28.9% in the Deep South reporting consistent condom use during vaginal and anal sex (p = 0.26). Regarding their home neighborhoods, men in the Deep South were more likely than those in Chicago to characterize theirs as having a good reputation (43.1% versus 24.7%, p < 0.001) and as being safe (37.3% versus 21.2%, p = 0.002). Conclusions: The focus on Black MSM in the N2 Study will allow for a nuanced exploration of the attitudes, beliefs, behaviors, and practices of a diverse group of Black MSM. The study is also positioned to provide novel insight about neighborhood and network characteristics that influence HIV-related behaviors. A health equity framework ensures that Black MSM are not explicitly or implicitly deemed as deviant, disordered, or the non-reference group. Findings from N2 will provide guidance for the implementation of more impactful HIV prevention interventions that engage a diverse population of Black MSM as we work toward HIV elimination in the U.S.

Prescription Opioid Use in a Population-Based Sample of Young Black Men Who Have Sex with Men: A Longitudinal Cohort Study

Background: Prescription opioid use (POU) among young adults is increasing. This represents a major public health concern due to the increased risks of opioid use misuse and opioid-related overdose. Limited research has examined the POU among young black men who have sex with men (YBMSM), a diverse group experiencing continued increases in HIV incidence over the past decade. Objective: This study aims to examine the prevalence and both the individual and network characteristics of POU among YBMSM. Methods: Data were from a longitudinal cohort study of 16-29 year old YBMSM (N = 514) between 2013 and 2016 in Chicago. Bivariate and multivariable associations were estimated using general estimating equations (GEE). Results: Approximately 4.2% of YBMSM reported POU in the past 12 months with a cumulative incidence rate of 4.1% over the 18-month follow-up period. YBMSM having criminal justice involvements, experiencing violence, or using any illicit drug other than marijuana in the past 12 months were more likely to report POU in the past 12 months. The presence of a mother figure, however, was associated with a decreased risk of POU in the past 12 months, while engaging in condomless anal sex with their named sexual partners was associated with an increased risk of POU in the past 12 months. Conclusions: This is one of the first studies to describe POU among a population-based sample of YBMSM. The high incidence rate of POU among YBMSM is alarming, and it underscores the need for further analysis on POU among this key population.

Human Immunodeficiency Virus Partner Notification Services Among a Representative Sample of Young Black Men Who Have Sex With Men Demonstrates Limited Service Offering and Potential Benefits of Clinic Involvement

BACKGROUND

Partner notification (PN) is commonly offered to persons recently diagnosed with human immunodeficiency virus (HIV) to improve linkage to care and prevent onward transmission. Yet, much remains unknown about the factors associated with successful PN participation in populations at highest risk.

METHODS

Data were collected during the first 2 waves (2013-2015) of "uConnect," a population-based cohort study of young black men who have sex with men in Chicago (N = 618). Participants completed a biobehavioral survey and were tested for HIV. Among HIV-infected participants (N = 187), weighted logistic regression models examined the relationship between participant characteristics and being offered PN and providing partner names.

RESULTS

30.3% (n = 187) of the sample was HIV-positive, of which 71.7% (n = 134) were offered PN, including: 8.2% (n = 11) by the city health department; 51.5% (n = 69) by health care providers; and 40.3% (n = 54) by both. Being offered PN was significantly associated with criminal justice involvement history (adjusted odds ratio [aOR], 2.49; 95% confidence interval [CI], 1.38-4.49), volatile nitrates usage (aOR, 2.88; 95% CI, 1.20-6.94), and recent conversations with HIV outreach workers (aOR, 2.68; 95% CI, 1.25-5.77). Providing partner names was significantly associated with intermittent (aOR, 7.26; 95% CI, 1.75-30.07) and heavy (aOR, 11.47; 95% CI, 2.57-51.22) marijuana use, and being offered PN by both the city health department and health care provider (aOR, 8.36; 95% CI, 2.73-25.62).

CONCLUSIONS

A substantial proportion of HIV-diagnosed individuals were never offered PN. Being offered PN by multiple sources is associated with participation, and improved collaboration within health systems may improve participation rates.

Network Viral Load: A Critical Metric for HIV Elimination

BACKGROUND

Associations have been observed between an aggregate viral load measure, the community viral load, and new HIV diagnoses. The community viral load aggregates viral loads within chosen geographic areas, restricting inferences about HIV acquisition risk to these areas. We develop a more precise metric, the network viral load (NVL), to measure the composite viral load within a risk network of a HIV-negative individual.

METHODS

We examined the relationship between NVL and HIV infection among young men who have sex with men in Chicago, United States. Networks were generated using respondent-driven sampling. NVL was defined as the prevalence of viremic individuals in one's risk network, characterized as those with a viral load ≥20 k copies per milliliter. Permutation tests were conducted to account for dependency.

RESULTS

After controlling for total connections, age, substance use during sex, syphilis diagnosis (previous 12 months), and frequency of condomless anal sex (previous 6 months), we found a positive association between NVL and HIV infection. Compared with a network with all HIV-seronegative members, the odds of HIV infection with an NVL of <10% viremia were 1.85 (95% confidence interval: 1.18 to 2.92) times higher and those with an NVL of ≥10% viremia were 2.73 (95% confidence interval: 1.54 to 4.85) times higher.

CONCLUSIONS

We found a positive association between NVL and HIV seroprevalence. Although limited in its ability to infer causality, NVL could have substantial public health implications for persons most at risk for HIV infection, given that this novel metric avoids overreliance on individual level behavior or broad community indices.

Sex Behaviors as Social Cues Motivating Social Venue Patronage Among Young Black Men Who Have Sex with Men

HIV prevention programs often focus on the physical social venues where men who have sex with men (MSM) frequent as sites where sex behaviors are assumed to be practiced and risk is conferred. But, how exactly these behaviors influence venue patronage is not well understood. In this study, we present a two-mode network analysis that determines the extent that three types of sex behaviors-condomless sex, sex-drug use, and group sex-influence the patronage of different types of social venues among a population sample of young Black MSM (YBMSM) (N = 623). A network analytic technique called exponential random graph modeling was used in a proof of concept analysis to verify how each sex behavior increases the likelihood of a venue patronage tie when estimated as either: (1) an attribute of an individual only and/or (2) a shared attribute between an individual and his peers. Findings reveal that sex behaviors, when modeled only as attributes possessed by focal individuals, were no more or less likely to affect choices to visit social venues. However, when the sex behaviors of peers were also taken into consideration, we learn that individuals were statistically more likely in all three behavioral conditions to go places that attracted other MSM who practiced the same behaviors. This demonstrates that social venues can function as intermediary contexts in which relationships can form between individuals that have greater risk potential given the venues attraction to people who share the same risk tendencies. As such, structuring interventions around these settings can be an effective way to capture the attention of YBMSM and engage them in HIV prevention.

PrEP Chicago: A randomized controlled peer change agent intervention to promote the adoption of pre-exposure prophylaxis for HIV prevention among young Black men who have sex with men

BACKGROUND/AIMS

Advances in biomedical prevention strategies such as pre-exposure prophylaxis (PrEP) represent a new opportunity for reducing HIV incidence among young Black men who have sex with men, for whom the number of new HIV infections continues to rise. However, studies have documented low rates of PrEP uptake in this community. Research suggests that the peer networks of young Black men who have sex with men play important roles in their sexual health decisions. PrEP Chicago is a randomized controlled trial network intervention designed to increase PrEP uptake among young Black men who have sex with men living in Chicago. The aims of this study are twofold. Aim 1 is to estimate the effectiveness of a peer change agent intervention for (1) increasing the number of referrals made to a PrEP information line, (2) increasing the rate of PrEP adoption among non-participant peers, and (3) increasing PrEP knowledge, attitudes, and intentions among participants. Aim 2 is to determine the individual and network variables that explain peer change agent effectiveness.

METHODS

PrEP Chicago is a social network intervention that utilizes the influence of peer change agents to link young Black men who have sex with men in Chicago to PrEP. Young Black men who have sex with men were recruited using respondent-driven sampling. Once screened for eligibility, participants were randomly assigned to either one of two treatment sequences: (1) intervention treatment in Year 1 followed by a minimal contact attention control in Year 2 or (2) the minimal contact attention control in Year 1 followed by treatment in Year 2. The treatment consists of a PrEP/peer change agent training workshop followed by booster calls for 12 months. The attention control consists of a sex diary activity designed to help participants assess sexual risk. Psychosocial, sexual health, and network data are collected from all participants at baseline and at 12- and 24-month follow-ups.

RESULTS

In total, 423 participants aged 18-35 have been enrolled (more than 100% target enrollment) and have completed baseline data collection. A majority of participants in both intervention and control groups reported having heard of PrEP before enrolling in the study, yet also reported having had no current or prior experience taking PrEP. Statistical analyses await completion of Year 1 of the trial in March 2018.

CONCLUSION

PrEP Chicago addresses a gap in HIV prevention research and intervention design by utilizing the existing social networks among young Black men who have sex with men as mechanisms for information diffusion, behavioral influence, social support, and empowerment. Therefore, interventions that leverage peer influence processes to facilitate PrEP uptake are promising strategies to improve sexual health engagement and overcome disparities in outcomes among this at-risk population.

Facebook network structure and awareness of preexposure prophylaxis among young men who have sex with men

BACKGROUND

Young Black men who have sex with men (YBMSM) are the only population in the United States who have experienced rising human immunodeficiency virus incidence over the past decade. Consistent pre-exposure prophylaxis (PrEP) use can substantially reduce the risk of human immunodeficiency virus acquisition. What differentiates those who become aware of PrEP, and those who do not, remains largely unknown.

METHODS

The social networks of YBMSM can impact their awareness of PrEP; to examine this impact, we used two waves of Facebook data from "uConnect"-a longitudinal cohort study of YBMSM in Chicago (n = 266).

RESULTS

While PrEP awareness increased from 45% at baseline to 75% at follow-up, its use remained low (4% and 6%). There were 88 PrEP-unaware individuals at baseline who became aware (BA) by follow-up, and 56 who remained persistently unaware. While the persistently unawares had a higher median number of total Facebook friends, the BAs had a higher median numbers of friends who participated in uConnect, who were PrEP-aware, and who practiced behaviors previously found to be associated with individual-level awareness of PrEP at baseline. The BAs also had substantially more "influential" friends.

CONCLUSION

These findings demonstrate the potential of social networks in raising PrEP awareness and use among YBMSM.

Marijuana Use Among Young Black Men Who Have Sex With Men and the HIV Care Continuum: Findings From the uConnect Cohort

BACKGROUND

Young Black men who have sex with men (YBMSM) are at highest risk for HIV seroconversion in the United States. Successful movement through the HIV care continuum is an important intervention for limiting onwards HIV transmission.

OBJECTIVE

Little data exists on how substances most commonly used by YBMSM, such as marijuana, are related to the HIV continuum, which represents the primary aim of this study.

METHODS

A cohort of YBMSM (n = 618) was generated through respondent-driven sampling. Frequency of marijuana use and marijuana use as a sex-drug were assessed across the HIV care continuum using weighted logistic regression models.

RESULTS

Study participants reported more intermittent marijuana use (n = 254, 56.2%) compared to heavy use (n = 198, 43.8%). Our sample contained 212 (34.3%) HIV seropositive participants of which 52 (24.5%) were unaware of their HIV positive status. Study participants who were heavy marijuana users were more likely to be unaware of their HIV seropositive status (AOR: 4.18; 95% CI 1.26, 13.89). All other stages in the care continuum demonstrated no significant differences between those who use marijuana intermittently or heavily or as a sex-drug and nonusers.

CONCLUSIONS

YBMSM who used marijuana heavily were more likely to be HIV-positive unaware than those who never used marijuana. Findings were inconclusive regarding the relationships between marijuana use and other HIV care continuum metrics. However, knowledge of ones' HIV status is a critical requirement for engaging in care and may have implications for onwards HIV transmission.

Estimating the impact of universal antiretroviral therapy for HIV serodiscordant couples through home HIV testing: insights from mathematical models

INTRODUCTION

Antiretroviral therapy (ART) prevents HIV transmission within HIV serodiscordant couples (SDCs), but slow implementation and low uptake has limited its impact on population-level HIV incidence. Home HIV testing and counselling (HTC) campaigns could increase ART uptake among SDCs by incorporating couples' testing and ART referral. We estimated the reduction in adult HIV incidence achieved by incorporating universal ART for SDCs into home HTC campaigns in KwaZulu-Natal (KZN), South Africa, and southwestern (SW) Uganda.

METHODS

We constructed dynamic, stochastic, agent-based network models for each region. We compared adult HIV incidence after 10 years under three scenarios: (1) "Current Practice," (2) "Home HTC" with linkage to ART for eligible persons (CD4 <350) and (3) "ART for SDCs" regardless of CD4, delivered alongside home HTC.

RESULTS

ART for SDCs reduced HIV incidence by 38% versus Home HTC: from 1.12 (95% CI: 0.98-1.26) to 0.68 (0.54-0.82) cases per 100 person-years (py) in KZN, and from 0.56 (0.50-0.62) to 0.35 (0.30-0.39) cases per 100 py in SW Uganda. A quarter of incident HIV infections were averted over 10 years, and the proportion of virally suppressed HIV-positive persons increased approximately 15%.

CONCLUSIONS

Using home HTC to identify SDCs and deliver universal ART could avert substantially more new HIV infections than home HTC alone, with a smaller number needed to treat to prevent new HIV infections. Scale-up of home HTC will not diminish the effectiveness of targeting SDCs for treatment. Increasing rates of couples' testing, disclosure, and linkage to care is an efficient way to increase the impact of home HTC interventions on HIV incidence.

Graphene based anticorrosive coatings for Cr(VI) replacement

Corrosion has been a perennial issue of concern for the steel industry. Chromate conversion coatings are well known pre-treatment coatings for steel but due to environmental concerns and legislations, their use has been restricted. The industrial community, pegged by these legislations, has been long demanding an economically viable and eco-friendly pre-treatment coating alternative, without having to compromise on the durability and corrosion performance of the overall coating system. The present study focuses on evaluation of graphene as an anticorrosive alternative to Cr(VI) based coatings. Graphene, produced by a high shear liquid exfoliation route, upon functionalisation, provides a conductive and nearly impermeable barrier coating. On electrochemical and coating performance evaluation of this coating system, a dramatic improvement in corrosion resistance is observed. The study confirms the environment friendly corrosion protection of steel using functionalised graphene coating.

Estimating PMTCT's Impact on Heterosexual HIV Transmission: A Mathematical Modeling Analysis

INTRODUCTION

Prevention of mother-to-child HIV transmission (PMTCT) strategies include combined short-course antiretrovirals during pregnancy (Option A), triple-drug antiretroviral treament (ART) during pregnancy and breastfeeding (Option B), or lifelong ART (Option B+). The WHO also recommends ART for HIV treatment and prevention of sexual transmission of HIV. The impact of PMTCT strategies on prevention of sexual HIV transmission of HIV is not known. We estimated the population-level impact of PMTCT interventions on heterosexual HIV transmission in southwestern Uganda and KwaZulu-Natal, South Africa, two regions with different HIV prevalence and fertility rates.

MATERIALS AND METHODS

We constructed and validated dynamic, stochastic, network-based HIV transmission models for each region. PMTCT Options A, B, and B+ were simulated over ten years under three scenarios: 1) current ART and PMTCT coverage, 2) current ART and high PMTCT coverage, and 3) high ART and PMTCT coverage. We compared adult HIV incidence after ten years of each intervention to Option A (and current ART) at current coverage.

RESULTS

At current coverage, Options B and B+ reduced heterosexual HIV incidence by about 5% and 15%, respectively, in both countries. With current ART and high PMTCT coverage, Option B+ reduced HIV incidence by 35% in Uganda and 19% in South Africa, while Option B had smaller, but meaningful, reductions. The greatest reductions in HIV incidence were achieved with high ART and PMTCT coverage. In this scenario, all PMTCT strategies yielded similar results.

DISCUSSION

Implementation of Options B/B+ reduces adult HIV incidence, with greater effect (relative to Option A at current levels) in Uganda than South Africa. These results are likely driven by Uganda's higher fertility rates.

Conceptual framework and research methods for migration and HIV transmission dynamics

Migration and mobility have had a profound influence on the global HIV epidemic. We propose a network-dyadic conceptual model to interpret previous literature and inform the development of future research with respect to study design, measurement methods, and analytic approach. In this model, HIV transmission is driven by risk behaviors of migrants that emerges and is enabled by mobility, the bridging of sub-epidemics across space and time, and the displacement effects on the primary residential sending community for migrants. To investigate these causal pathways, empirical study designs must measure the relative timing of migratory events, sexual risk behaviors, and incident HIV infections. Network-based mathematical models using empirical data on partnerships help gain insight into the dynamic disease transmission systems. Although the network-dyadic conceptual model and related network methods may not address all questions related to migration and HIV, they provide a unified approach for future research on this important topic.

Modeling the impact of post-diagnosis behavior change on HIV prevalence in Southern California men who have sex with men (MSM)

Our objective here is to demonstrate the population-level effects of individual-level post-diagnosis behavior change (PDBC) in Southern Californian men who have sex with men (MSM), recently diagnosed with HIV. While PDBC has been empirically documented, the population-level effects of such behavior change are largely unknown. To examine these effects, we develop network models derived from the exponential random graph model family. We parameterize our models using behavioral data from the Southern California Acute Infection and Early Disease Research Program, and biological data from a number of published sources. Our models incorporate vital demographic processes, biology, treatment and behavior. We find that without PDBC, HIV prevalence among MSM would be significantly higher at any reasonable frequency of testing. We also demonstrate that higher levels of HIV risk behavior among HIV-positive men relative to HIV-negative men observed in some cross-sectional studies are consistent with individual-level PDBC.

3H-spiroperidol binding sites in blood platelets

3H-spiroperidol, an antagonist of dopamine receptors in brain (striatum), was found to bind to human and rat platelet membrane preparations. The binding was rapid, reversible, saturable and specific. Unlabelled haloperidol displaced the specifically bound 3H-spiroperidol. Binding equilibrium was attained in 15 min at pH 7.4 and 37 degrees C. Scatchard analysis of 3H-spiroperidol binding revealed a single population of binding site with Kd of 7.6 nM in rat platelet membrane and Kd of 15 nM in human platelet membrane. Unlabelled 5-hydroxytryptamine produced no significant effect on 3H-spiroperidol binding to rat or human blood platelet membranes in the presence or absence of haloperidol. Some dopaminergic agents, known to inhibit spiroperidol binding in corpus striatum, also inhibited the same in rat and human blood platelet membranes under in vitro conditions. This study suggests the presence of specific 3H-spiroperidol binding sites in blood platelets.