Racial/ethnic disparities in the association between patient care experiences and receipt of initial surgical breast cancer care: findings from SEER-CAHPS.

PURPOSE: We determined whether racial/ethnic differences in patient experiences with care influence timeliness and type of initial surgical breast cancer treatment for a sample of female Medicare cancer patients. METHODS: We conducted a retrospective cohort study using the linked Epidemiology and End Results-Consumer Assessment of Healthcare Providers and Systems (SEER-CAHPS) dataset. The outcomes were: (1) time-to-initial surgical treatment, and (2) type of treatment [breast conserving surgery (BCS) vs. mastectomy]. The indicators were reports of four types of patient experiences with care including doctor communication, getting care quickly, getting needed care, and getting needed Rx. Interaction terms in each multivariable logistic model examined if the associations varied by race/ethnicity. RESULTS: Of the 2069 patients, 84.6% were White, 7.6% Black and 7.8% Hispanic. After adjusting for potential confounders, non-Hispanic Black patients who provided excellent reports of their ability to get needed prescriptions had lower odds of receiving surgery within 2-months of diagnosis, compared to NH-Whites who provided less than excellent reports (aOR: 0.29, 95% CI 0.09-0.98). There were no differences based on 1-month or 3-month thresholds. We found no other statistically significant effect of race/ethnicity. As to type of surgery, among NH Blacks, excellent reports of getting care quickly were associated with higher odds of receiving BCS versus mastectomy (aOR: 2.82, 95% CI 1.16-6.85) compared to NH Whites with less than excellent reports. We found no other statistically significant differences by race/ethnicity. CONCLUSION: Experiences with care are measurable and modifiable factors that can be used to assess and improve aspects of patient-centered care. Improvements in patient care experiences of older adults with cancer, particularly among minorities, may help to eliminate racial/ethnic disparities in timeliness and type of surgical treatment.

Latent classification model for censored longitudinal binary outcome.

Latent classification model is a class of statistical methods for identifying unobserved class membership among the study samples using some observed data. In this study, we proposed a latent classification model that takes a censored longitudinal binary outcome variable and uses its changing pattern over time to predict individuals' latent class membership. Assuming the time-dependent outcome variables follow a continuous-time Markov chain, the proposed method has two primary goals: (1) estimate the distribution of the latent classes and predict individuals' class membership, and (2) estimate the class-specific transition rates and rate ratios. To assess the model's performance, we conducted a simulation study and verified that our algorithm produces accurate model estimates (ie, small bias) with reasonable confidence intervals (ie, achieving approximately 95% coverage probability). Furthermore, we compared our model to four other existing latent class models and demonstrated that our approach yields higher prediction accuracies for latent classes. We applied our proposed method to analyze the COVID-19 data in Houston, Texas, US collected between January first 2021 and December 31st 2021. Early reports on the COVID-19 pandemic showed that the severity of a SARS-CoV-2 infection tends to vary greatly by cases. We found that while demographic characteristics explain some of the differences in individuals' experience with COVID-19, some unaccounted-for latent variables were associated with the disease.

Prevalence, Incidence, and Predictors of Kaposi Sarcoma-associated Herpesvirus Infection Among Young Men Who Have Sex with Men in the Southern United States.

Kaposi Sarcoma (KS) continues to cause substantial morbidity and mortality in populations at risk in the southern US. Utilizing biospecimens from the Houston site of the Young Men's Affiliate Project, 351 men who have sex with men had blood tested for Kaposi Sarcoma-associated herpesvirus (KSHV) IgG. Measuring seroprevalence, seroconversion between timepoints, and demographic and clinical correlates, KSHV prevalence was 36.7% and incidence was 8.9 per 100 person-years, prevalence and incidence were higher among Black individuals, people living with HIV, and those with a history of syphilis. Further research on KSHV risk may improve health disparities in KS diagnosis and outcomes.

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.

Factors associated with HIV testing and treatment among young Black MSM and trans women in three jail systems.

Black men who have sex with men (BMSM) and transgender women (BTW) are disproportionately affected by incarceration and HIV. We assessed factors associated with HIV testing and viral suppression among 176 incarcerated BMSM and BTW in Chicago, IL; Los Angeles, CA; and Houston, TX. In multivariable logistic regression, having a sexual orientation of bisexual, heterosexual, or other vs. gay or same-gender loving was associated with higher odds of testing in custody (aOR 8.97; 95% CI 1.95 - 41.24). Binge drinking (aOR 0.19; 95% CI 0.04 - 0.92) and being unemployed prior to incarceration (aOR 0.03; 95% CI 0.00 - 0.23) were associated with lower odds of testing; participants in Los Angeles were also more likely to be tested than those in Chicago. Being housed in protective custody (aOR 3.12; 95% CI 1.09-9.59) and having a prescription for ART prior to incarceration (aOR 2.58; 95% CI 1.01-6.73) were associated with higher odds of viral suppression when adjusted for site and duration of incarceration, though the associations were not statistically significant in the full multivariable model. Future research should examine structural and process level factors that impact engagement in HIV testing and treatment among detained BMSM and BTW.

Sexual Behaviors and Human Papillomavirus Vaccination in a Heterosexually Active Adult Population at Increased Risk for HIV Infection.

Human papillomavirus (HPV) is the most common sexually acquired infection in the US. Vaccination is effective against infection with high-risk HPV strains, yet HPV vaccine coverage is lower in the US than the national target. This study aimed to determine the relationship between sexual behaviors and HPV vaccination in a heterosexually active population at increased risk for HIV infection. Data from 380 participants aged 18-45 years obtained from the National HIV Behavioral Surveillance system increased risk heterosexuals cycle 5 (2019) in Houston, Texas, was analyzed. RDS-Analyst was used to generate population-based descriptive statistics. Modified Poisson regression models clustered on recruitment chain were conducted in SAS 9.4 to assess the relationship between sexual behaviors and HPV vaccination. Only 11.5% of participants had received at least one dose of the HPV vaccine. Regarding behaviors within the past 12 months, 44.8% reported having condomless casual sex, 51.3% reported having concurrent sexual partnerships while in their most recent relationship, 14.5% reported exchanging sex, and participants had an average of 4-5 sex partners. Further, those who exchanged sex had a significantly lower prevalence of HPV vaccine uptake when compared to those who did not exchange sex (adjusted prevalence ratio 0.23; confidence interval 0.10-0.52), while all other measures of sexual behavior were not significantly associated with HPV vaccination. More research is needed to understand the relationship between exchange sex and low prevalence of vaccination, specifically in women who bear the highest burden of poor HPV-related morbidity and mortality.

Social networks, high-risk anal HPV and coinfection with HIV in young sexual minority men.

OBJECTIVES: Young sexual minority men (SMM) exhibit a high prevalence and incidence of high-risk genotypes of human papillomavirus (hrHPV) anal infections and a confluence of a high prevalence of HIV and rectal STIs. Social determinants of health (SDOHs) are linked to social network contexts that generate and maintain racial disparities in HIV and STIs. A network perspective was provided to advance our knowledge of drivers of genotype-specific hrHPV infection and coinfection with HIV. The study also examined whether socially connected men are infected with the same high-risk HPV genotypes and, if so, whether this tendency is conditioned on coinfection with HIV. METHODS: Our sample included 136 young SMM of predominantly black race and their network members of other races and ethnicities, aged 18-29 years, who resided in Houston, Texas, USA. These participants were recruited during 2014-2016 at the baseline recruitment period by network-based peer referral, where anal exfoliated cells and named social and sexual partners were collected. Exponential random graph models were estimated to assess similarity in genotype-specific hrHPV anal infection in social connections and coinfection with HIV in consideration of the effects of similarity in sociodemographic, sexual behavioural characteristics, SDOHs and syphilis infection. RESULTS: Pairs of men socially connected to each other tend to be infected with the same hrHPV genotypes of HPV-16, HPV-45 and HPV-51 or HPV-16 and/or HPV-18. The tendency of social connections between pairs of men who were infected with either HPV-16 or HPV-18 were conditioned on HIV infection. CONCLUSIONS: Networked patterns of hrHPV infection could be amenable to network-based HPV prevention interventions that engage young SMM of predominantly racial minority groups who are out of HIV care and vulnerable to high-risk HPV acquisition.

HIV Response Interventions that Integrate HIV Molecular Cluster and Social Network Analysis: A Systematic Review.

Due to improved efficiency and reduced cost of viral sequencing, molecular cluster analysis can be feasibly utilized alongside existing human immunodeficiency virus (HIV) prevention strategies. The goal of this paper is to elucidate how HIV molecular cluster and social network analyses are being integrated to implement HIV response interventions. We searched PubMed, Scopus, PsycINFO, and Cochrane Library databases for studies incorporating both HIV molecular cluster and social network data. We identified 32 articles that combined analyses of HIV molecular sequences and social or sexual networks. All studies were descriptive. Six studies described network interventions informed by molecular and social data but did not fully evaluate their efficacy. There is no current standard for incorporating molecular and social network analyses to inform interventions or data demonstrating its utility. More research must be conducted to delineate benefits and best practices for leveraging molecular data for network-based interventions.

RESUMEN: Debido a mejor eficiencia y costo reducido de la secuenciación viral, el análisis de complejos moleculares se puede utilizar de manera factible junto con las estrategias de prevención del virus de inmunodeficiencia humana (VIH) existentes. El objetivo de este repaso es de aclarar como integrar los análisis de las redes sociales y de los complejos moleculares del VIH para implementar intervenciones para controlar el VIH. Buscamos en las bases de datos de PubMed, Scopus, PsycINFO y Cochrane Library por estudios que incorporaran datos de redes sociales y grupos moleculares del VIH. Identificamos 32 estudios que combinaban análisis de secuencias moleculares del VIH y datos de redes sociales. Todos los estudios fueron descriptivos. Seis estudios describieron intervenciones informadas por datos moleculares y sociales, pero no evaluaron completamente su eficacia. No existe un estándar actual para incorporar análisis moleculares y sociales para informar intervenciones o datos que demuestren su eficacia. Se deben realizar más investigaciones para delinear los beneficios y las mejores prácticas de aplicar los datos moleculares y sociales para crear intervenciones del VIH.

Community-clinic linkages for promoting HIV prevention: organizational networks for PrEP client referrals and collaborations.

Community-clinic linkages may help communities increase HIV pre-exposure prophylaxis (PrEP) uptake. Referrals from community-based organizations may be particularly important for linking Black men who have sex with men (MSM) to PrEP. This study describes PrEP referral and HIV/STI prevention networks among organizations that serve MSM in Houston, TX (N = 40), and Chicago, IL (N = 28), and compares network positions of organizations based on percentage of Black/African American clients. A majority of organizations conducted PrEP awareness/promotion activities, but fewer made PrEP referrals, with little overlap between the collaboration and referral networks. The networks tended to have a densely connected core group of organizations and more a peripheral group of organizations linking into the core with relatively few times among themselves; this core/periphery structure is efficient, but vulnerable to disruptions. The percentage of Black/African American clients organizations served was not related to most measures of network centrality. However, in Houston's collaboration network, higher Black-serving organizations tended not to hold as influential positions for controlling communications or flows of resources. The findings indicate a potential to leverage collaborations into PrEP referral pathways to enhance PrEP promotion efforts and identify opportunities to address racial disparities in PrEP uptake.

The association between egocentric sexual networks and sexual meeting venues with PrEP conversation and encouragement for use among Latinx men who have sex with men.

Despite the increasing availability of pre-exposure prophylaxis (PrEP), Latinx men who have sex with men (LMSM) are not receiving PrEP-related information. To understand the influence of LMSM sexual networks on PrEP-related conversations and encouragement to use PrEP, this cross-sectional egocentric network study characterized the PrEP-related communication of 130 LMSM egos with 507 sexual partners (alters). Participants were recruited using respondent-driven sampling methods from a Miami-Dade County community-health organization. Egocentric-level data were collected from 2018-2019 and analyzed using multilevel modeling. Of egos, 30% reported using PrEP. Closeness between participants and sexual partners played a role in PrEP conversation and encouragement. Participants believed they would have less success convincing sexual partners to use PrEP if partners were older. Participants perceived higher likelihood to talk about PrEP or success in encouraging alters to use PrEP if, relative to meeting sexual partners on Grindr, they met at a friend's party, gay-centric community event, or school/work. Given that increased closeness and in-person sexual partner meeting venues are associated with PrEP information dissemination and encouragement, social network-based interventions can capitalize on PrEP navigators who run network visualizations, and with this information develop a longitudinal plan to increase PrEP conversation and encouragement as needed for each network.

Acceptance- and mindfulness-based techniques for physical activity promotion in breast cancer survivors: a qualitative study.

PURPOSE: The purpose of this study was to develop and characterize the relevance and potential utility of an electronically delivered acceptance- and mindfulness-based approaches to physical activity promotion for insufficiently active breast cancer survivors. METHODS: The acceptance- and mindfulness-based physical activity intervention was delivered to participants electronically over the course of 4-8 weeks. It consisted of didactic videos, experiential exercises, and workbook-type activities that targeted principles from acceptance and commitment therapy (ACT). We conducted semi-structured, in-depth interviews with participants after they completed the intervention. Three coders conducted qualitative data analysis on interview transcripts to identify overarching themes and subthemes. RESULTS: We recruited 30 participants. Of those, 16 engaged in an individual interview. The mean age of the sample was 58.4 years (SD = 13.8). The sample was relatively well educated (50.0% college graduates) and mostly overweight or obese (58.8%). We identified two overarching themes from interviews. They were centered on (1) internal and external barriers to physical activity adherence and (2) the utility of targeting core ACT processes (acceptance and defusion, mindfulness, and values clarification) for physical activity promotion. CONCLUSION: Intervention content was perceived to be acceptable, relevant, and to fulfill important needs related to healthy living. Findings suggest that this approach to physical activity promotion can be delivered effectively online. Electronically delivered acceptance- and mindfulness-based approaches hold promise for helping insufficiently active breast cancer survivors increase physical activity.

Integrated molecular and affiliation network analysis: Core-periphery social clustering is associated with HIV transmission patterns.

This study investigates the two-mode core-periphery structures of venue affiliation networks of younger Black men who have sex with men (YBMSM). We examined the association between these structures and HIV phylogenetic clusters, defined as members who share highly similar HIV strains that are regarded as a proxy for sexual affiliation networks. Using data from 114 YBMSM who are living with HIV in two large U.S. cities, we found that HIV phylogenetic clustering patterns were associated with social clustering patterns whose members share affiliation with core venues that overlap with those of YBMSM. Distinct HIV transmission patterns were found in each city, a finding that can help to inform tailored venue-based and network intervention strategies.

Sexual and social networks, venue attendance, and HIV risk among young men who have sex with men.

OBJECTIVE: This study used a Social network analysis (SNA) approach to describe HIV transmission and venue affiliations among social and sexual networks of young men who have sex with men (YMSM) in Houston, TX. METHODS: A total of 34 YMSM indices aged 18-23 years and 23 of their network members were interviewed about their social and sexual networks and venues at which they met and spent time. RESULTS: Participants reported information on 220 friends (mean age = 25.3 years) and 112 sexual partners (mean age = 26.3 years). Participants spent time with friends and sexual partners at similar venues but relied more heavily on social media and dating applications to meet sexual partners. Participants lived in zip codes consistent with high concentrations of HIV positivity. Popularly frequented clubs/gay bars were often 10-20 miles away, also in zip codes with high densities of seropositivity. CONCLUSION: Both friendship and sexual networks are large, diffuse, and not limited by geography. Participants came from areas with high rates of HIV/AIDS. The venues at which participants recruited sexual partners may present increased opportunities for HIV transmission. HIV prevention interventions should focus on the heightened risk of unknown HIV serostatus.

"Down the Rabbit Hole" of Vaccine Misinformation on YouTube: Network Exposure Study.

BACKGROUND: Social media platforms such as YouTube are hotbeds for the spread of misinformation about vaccines. OBJECTIVE: The aim of this study was to explore how individuals are exposed to antivaccine misinformation on YouTube based on whether they start their viewing from a keyword-based search or from antivaccine seed videos. METHODS: Four networks of videos based on YouTube recommendations were collected in November 2019. Two search networks were created from provaccine and antivaccine keywords to resemble goal-oriented browsing. Two seed networks were constructed from conspiracy and antivaccine expert seed videos to resemble direct navigation. Video contents and network structures were analyzed using the network exposure model. RESULTS: Viewers are more likely to encounter antivaccine videos through direct navigation starting from an antivaccine video than through goal-oriented browsing. In the two seed networks, provaccine videos, antivaccine videos, and videos containing health misinformation were all found to be more likely to lead to more antivaccine videos. CONCLUSIONS: YouTube has boosted the search rankings of provaccine videos to combat the influence of antivaccine information. However, when viewers are directed to antivaccine videos on YouTube from another site, the recommendation algorithm is still likely to expose them to additional antivaccine information.

Operationalizing patient-centered cancer care: A systematic review and synthesis of the qualitative literature on cancer patients' needs, values, and preferences.

OBJECTIVE: Efficiently addressing patient priorities and concerns remains a challenge in oncology. Systematic operationalization of patient-centered care (PCC) can support improved assessment and practice of PCC in this unique care setting. This review aimed to synthesize the qualitative empirical literature exploring the National Academy of Medicine (NAM)'s PCC constructs of values, needs, and preferences among patients' during their cancer treatment experiences. METHODS: A systematic review of qualitative studies published between 2002 and 2018 addressing adult patient values, needs, and preferences during cancer treatment was conducted. Medline, EMBASE, PsycINFO, and SCOPUS databases were searched on September 10, 2018. Methodological rigor was assessed using a modified version of the Evaluation Tool for Qualitative Studies. Included study findings were analyzed using line-by-line coding; and the emergent themes were compared to the National Academy of Medicine (NAM)'s PCC dimensions. RESULTS: Twenty-nine primary studies were included in the synthesis. Descriptive themes for values (autonomy, being involved, family, hope, normality, and sincerity), needs (care coordination, information, privacy, support of physical well-being, emotional support (family/friends, peer, provider), and self-support), and preferences (care coordination, decision-making, information delivery, source of social support, and treatment) were identified. "Cancer care context" emerged as an important domain in which these constructs are operationalized. This thematic framework outlines PCC attributes that oncology care stakeholders can evaluate to improve patient experiences. CONCLUSIONS: These findings build on previous PCC research and may contribute to the systematic assessment of patient priorities and the improvement of oncology care quality from the patient perspective.

Exploratory Factor Analysis of a Patient-Centered Cancer Care Measure to Support Improved Assessment of Patients' Experiences.

OBJECTIVE: To increase the understanding of patient-centered care (PCC) and address the need for cross-cutting quality cancer care measures that are relevant to both patients and providers. METHODS: An exploratory factor analysis (EFA) was performed on a short version of the Patients and the Cancer Care Experience Survey, a patient-reported measure of perceived importance of social, emotional, physical, and informational aspects of care, administered to adult patients (n = 104) at a National Cancer Institute-designated comprehensive cancer center. Relationships between PCC dimensions and patient characteristics were also assessed. Principal axis factoring was applied and bivariate analyses were performed using Wilcoxon rank-sum tests. RESULTS: Most of our sample was over 60 years old (63.4%), female (57.4%), and white (74.2%), with either breast (41.2%) or prostate cancer (27.5%). A 5-factor model was identified: (1) quality of life (α = .91), (2) provider social support (α = .83), (3) psychosocial needs (α = .91), (4) nonprovider social support (α = .79), and (5) health information and decision-making support (α = .88). No statistically significant associations were found between these factors and patients' characteristics. CONCLUSIONS: A preliminary factor structure for a cancer PCC measure was identified. Our findings reinforce the interrelated nature of PCC dimensions. The lessons learned from this study may be used to develop a single PCC measure that identifies patient priorities across the cancer care continuum. Data collected from such a measure can be used to support patient engagement in treatment planning and decision-making.

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.

Friend of a Friend with Benefits ontology (FOAF+): extending a social network ontology for public health.

BACKGROUND: Dyadic-based social networks analyses have been effective in a variety of behavioral- and health-related research areas. We introduce an ontology-driven approach towards social network analysis through encoding social data and inferring new information from the data. METHODS: The Friend of a Friend (FOAF) ontology is a lightweight social network ontology. We enriched FOAF by deriving social interaction data and relationships from social data to extend its domain scope. RESULTS: Our effort produced Friend of a Friend with Benefits (FOAF+) ontology that aims to support the spectrum of human interaction. A preliminary semiotic evaluation revealed a semantically rich and comprehensive knowledge base to represent complex social network relationships. With Semantic Web Rules Language, we demonstrated FOAF+ potential to infer social network ties between individual data. CONCLUSION: Using logical rules, we defined interpersonal dyadic social connections, which can create inferred linked dyadic social representations of individuals, represent complex behavioral information, help machines interpret some of the concepts and relationships involving human interaction, query network data, and contribute methods for analytical and disease surveillance.

Neighbourhoods, networks and pre-exposure prophylaxis awareness: a multilevel analysis of a sample of young black men who have sex with men.

OBJECTIVE: Young black men who have sex with men (YBMSM) in the USA represent a subgroup that has the highest HIV incidence among the overall population. In the USA, pre-exposure prophylaxis (PrEP) is an effective prevention intervention to prevent HIV acquisition when taken regularly. Neighbourhood and network factors may relate to PrEP awareness, but have not been studied in YBMSM. This study aimed to examine the relationship of neighbourhood and network characteristics with PrEP awareness among YBMSM. METHODS: We used data collected from a sample of 618 YBMSM in Chicago (2013-2014). Home addresses were collected for participants and enumerated network members. Administrative data (eg, 2014 American Community Survey, Chicago Department of Public Health) were used to describe residence characteristics. Network member characteristics were also collected (eg, sexual partners' sex-drug use, confidant network members who were also MSM). Multilevel analysis was performed to examine the relationships of neighbourhood and network characteristics to PrEP awareness. RESULTS: Higher neighbourhood-level educational attainment (adjusted odds ratio (aOR) 1.02, p=0.03) and greater primary care density (aOR 1.38, p=0.01) were associated with greater PrEP awareness; greater neighbourhood alcohol outlet density (aOR 0.52, p=0.004) was associated with less PrEP awareness. Sexual network members residing in the same neighbourhood as the participants (aOR 2.58, p=0.03) and discussions around avoiding HIV acquisition with confidants (aOR 2.26, p=0.04) were associated with greater PrEP awareness. CONCLUSIONS: The results suggest that neighbourhood and network characteristics can influence PrEP awareness in YBMSM. Additional studies are needed to understand the influences of neighbourhood (eg, MSM serving venues) and network (eg, peer to peer communication) characteristics on dissemination of PrEP information, uptake and adherence and the related mechanisms behind the associations.

Network Modeling of PrEP Uptake on Referral Networks and Health Venue Utilization Among Young Men Who Have Sex with Men.

The objective of this study is to identify individual-level factors and health venue utilization patterns associated with uptake of pre-exposure prophylaxis (PrEP) and to evaluate whether PrEP uptake behavior is further diffused among young men who have sex with men (YMSM) through health venue referral networks. A sample of 543 HIV-seronegative YMSM aged 16-29 were recruited in 2014-2016 in Chicago, IL, and Houston, TX. Stochastic social network models were estimated to model PrEP uptake. PrEP uptake was associated with more utilization of health venues in Houston and higher levels of sexual risk behavior in Chicago. In Houston, both Hispanic and Black YMSM compared to White YMSM were less likely to take PrEP. No evidence was found to support the spread of PrEP uptake via referral networks, which highlights the need for more effective PrEP referral network systems to scale up PrEP implementation among at-risk YMSM.