Immune profiling in Puerto Rican injection drug users with and without HIV-1 infection

Antiretroviral therapy has been effective in suppressing HIV viral load and enabling people living with HIV to experience longer, more conventional lives. However, as people living with HIV are living longer, they are developing aging-related diseases prematurely and are more susceptible to comorbidities that have been linked to chronic inflammation. Coincident with HIV infection and aging, drug abuse has also been independently associated with gut dysbiosis, microbial translocation, and inflammation. Here, we hypothesized that injection drug use would exacerbate HIV-induced immune activation and inflammation, thereby intensifying immune dysfunction. We recruited 50 individuals not using injection drugs (36/50 HIV+) and 47 people who inject drugs (PWID, 12/47 HIV+). All but 3 of the HIV+ subjects were on antiretroviral therapy. Plasma immune profiles were characterized by immunoproteomics, and cellular immunophenotypes were assessed using mass cytometry. The immune profiles of HIV+/PWID-, HIV-/PWID+, and HIV+/PWID+ were each significantly different from controls; however, few differences between these groups were detected, and only 3 inflammatory mediators and 2 immune cell populations demonstrated a combinatorial effect of injection drug use and HIV infection. In conclusion, a comprehensive analysis of inflammatory mediators and cell immunophenotypes revealed remarkably similar patterns of immune dysfunction in HIV-infected individuals and in people who inject drugs with and without HIV-1 infection.

Final Study Report of Andexanet Alfa for Major Bleeding With Factor Xa Inhibitors

BACKGROUND

Andexanet alfa is a modified recombinant inactive factor Xa (FXa) designed to reverse FXa inhibitors. ANNEXA-4 (Andexanet Alfa, a Novel Antidote to the Anticoagulation Effects of Factor Xa Inhibitors) was a multicenter, prospective, phase-3b/4, single-group cohort study that evaluated andexanet alfa in patients with acute major bleeding. The results of the final analyses are presented.

METHODS

Patients with acute major bleeding within 18 hours of FXa inhibitor administration were enrolled. Co-primary end points were anti-FXa activity change from baseline during andexanet alfa treatment and excellent or good hemostatic efficacy, defined by a scale used in previous reversal studies, at 12 hours. The efficacy population included patients with baseline anti-FXa activity levels above predefined thresholds (≥75 ng/mL for apixaban and rivaroxaban, ≥40 ng/mL for edoxaban, and ≥0.25 IU/mL for enoxaparin; reported in the same units used for calibrators) who were adjudicated as meeting major bleeding criteria (modified International Society of Thrombosis and Haemostasis definition). The safety population included all patients. Major bleeding criteria, hemostatic efficacy, thrombotic events (stratified by occurring before or after restart of either prophylactic [ie, a lower dose, for prevention rather than treatment] or full-dose oral anticoagulation), and deaths were assessed by an independent adjudication committee. Median endogenous thrombin potential at baseline and across the follow-up period was a secondary outcome.

RESULTS

There were 479 patients enrolled (mean age, 78 years; 54% male, 86% White; 81% anticoagulated for atrial fibrillation at a median time of 11.4 hours since last dose, with 245 (51%) on apixaban, 176 (37%) on rivaroxaban, 36 (8%) on edoxaban, and 22 (5%) on enoxaparin. Bleeding was predominantly intracranial (n=331 [69%]) or gastrointestinal (n=109 [23%]). In evaluable apixaban patients (n=172), median anti-FXa activity decreased from 146.9 ng/mL to 10.0 ng/mL (reduction, 93% [95% CI, 94-93]); in rivaroxaban patients (n=132), it decreased from 214.6 ng/mL to 10.8 ng/mL (94% [95% CI, 95-93]); in edoxaban patients (n=28), it decreased from 121.1 ng/mL to 24.4 ng/mL (71% [95% CI, 82-65); and in enoxaparin patients (n=17), it decreased from 0.48 IU/mL to 0.11 IU/mL (75% [95% CI, 79-67]). Excellent or good hemostasis occurred in 274 of 342 evaluable patients (80% [95% CI, 75-84]). In the safety population, thrombotic events occurred in 50 patients (10%); in 16 patients, this occurred during treatment with prophylactic anticoagulation that began after the bleeding event. No thrombotic episodes occurred after oral anticoagulation restart. Specific to certain populations, reduction of anti-FXa activity from baseline to nadir significantly predicted hemostatic efficacy in patients with intracranial hemorrhage (area under the receiver operating characteristic curve, 0.62 [95% CI, 0.54-0.70]) and correlated with lower mortality in patients <75 years of age (adjusted P=0.022; unadjusted P=0.003). Median endogenous thrombin potential was within the normal range by the end of andexanet alfa bolus through 24 hours for all FXa inhibitors.

CONCLUSIONS

In patients with major bleeding associated with the use of FXa inhibitors, treatment with andexanet alfa reduced anti-FXa activity and was associated with good or excellent hemostatic efficacy in 80% of patients.

REGISTRATION

URL: https://www.

CLINICALTRIALS

gov; Unique identifier: NCT02329327.

Social Network Analysis of an Agricultural Center: Stakeholders and the Transfer of Information

We conducted a social network analysis (SNA) of Central States Center for Agricultural Safety and Health (CS-CASH) to describe stakeholder networks for agricultural Research and Education/Outreach. This was a two-phase study. First, the Leader Survey went to N = 9 CS-CASH leaders to identify their key stakeholders. Next, the Stakeholder Survey was sent to these stakeholders to learn about their stakeholder collaborations, interactions, and communications. The Pajek Network Analysis measured SNA metrics for density, centrality, betweenness, k-core, and created the sociograms. The Leader Survey had a 100% response rate and generated N = 337 unique stakeholders. Most were researchers (44%) and educators (20%), with a primary sphere of influence in Nebraska-only (40%). The Stakeholder Survey had 46% response rate, and generated N = 199 names in the extended Education/Outreach network and N = 140 in the extended Research network. Stakeholders in both networks were employed mostly in universities/schools (61%) or non-profits (15%). Both networks had a single main component and 7/9 CS-CASH leaders had central roles in these components. CS-CASH is well positioned in the extended stakeholder networks based on SNA metrics. Stakeholders utilize CS-CASH resources, and they seek and exchange information with its leaders. To strengthen knowledge transfer, it will be useful to build on connections with stakeholders outside academia.

Employing Respondent Driven Sampling (RDS) to recruit people who inject drugs (PWID) and other hard-to-reach populations during COVID-19: Lessons learned

BACKGROUND

Respondent Driven Sampling (RDS) is an effective sampling strategy to recruit hard-to-reach populations but the impact of the COVID-19 pandemic on the use of this strategy in the collection of data involving human subjects, particularly among marginalized and vulnerable populations, is not known. Based on an ongoing study using RDS to recruit and study the interactions between HIV infection, injection drug use, and the microbiome in Puerto Rico, this paper explores the effectiveness of RDS during the pandemic and provided potential strategies that could improve recruitment and data collection.

RESULTS

RDS was employed to evaluate its effectiveness in recruiting a group of people who inject drugs (PWID) and controls (N = 127) into a study in the midst of the COVID-19 pandemic. The participants were distributed among three subsets: 15 were HIV+ and PWID, 58 were HIV- PWID, and 54 were HIV+ and not PWID.

FINDINGS

Results show that recruitment through peer networks using RDS was possible across all sub-groups. Yet, while those in the HIV+ PWID sub-group managed to recruit from other-sub groups of HIV- PWID and HIV+, this occurred at a lower frequency.

CONCLUSION

Despite the barriers introduced by COVID-19, it is clear that even in this environment, RDS continues to play a powerful role in recruiting hard-to-reach populations. Yet, more attention should be paid at how future pandemics, natural disasters, and other big events might affect RDS recruitment of vulnerable and hard-to-reach populations.

Social Integration and Domestic Violence Support in an Indigenous Community: Women's Recommendations of Formal Versus Informal Sources of Support

Throughout North America, indigenous women experience higher rates of intimate partner violence and sexual violence than any other ethnic group, and so it is of particular importance to understand sources of support for Native American women. In this article, we use social network analysis to study the relationship between social integration and women's access to domestic violence support by examining the recommendations they would give to another woman in need. We ask two main questions: First, are less integrated women more likely to make no recommendation at all when compared with more socially integrated women? Second, are less integrated women more likely than more integrated women to nominate a formal source of support rather than an informal one? We use network data collected from interviews with 158 Canadian women residing in an indigenous community to measure their access to support. We find that, in general, less integrated women are less likely to make a recommendation than more integrated women. However, when they do make a recommendation, less integrated women are more likely to recommend a formal source of support than women who are more integrated. These results add to our understanding of how access to two types of domestic violence support is embedded in the larger set of social relations of an indigenous community.

"He's under oath": Privacy and Confidentiality Views Among People Who Inject Drugs Enrolled in a Study of Social Networks and Human Immunodeficiency Virus/Hepatitis C Virus Risk

Despite the promise of social network research, this method raises important ethical questions regarding privacy and confidentiality. Although researchers and bioethicists have considered research obligations in relation to marginal or vulnerable populations, the views of people who inject drugs (PWIDs) have not been sufficiently considered. To elicit participants' views of research obligations, we conducted in-depth interviews with a subset (n = 40) of active PWIDs enrolled in a large social network study. Findings suggest participants have an expectation of confidentiality but believe this obligation need not be absolute and can be waived if a participant violates community norms or place others at risk. Ethics boards should recognize that marginalized populations are able to articulate complex moral views about privacy and confidentiality. Engaging participants in dialogue about the responsible conduct of research presents an opportunity to correct under- or overestimations of research vulnerabilities when such decisions are restricted to the perspectives of investigators or Institutional Review Board members.

Treatment trajectories and barriers in opioid agonist therapy for people who inject drugs in rural Puerto Rico

BACKGROUND

Research has shown medication for opioid use disorder (MOUD) to have positive effects, including reducing HIV and HCV transmission, but important barriers to access remain among people who inject drugs (PWID). Barriers include lack of social and familial support, bureaucracy, distance to treatment, poverty, and homelessness. However, we know little about how these barriers interact with each other to shape PWID's drug treatment access and retention.

METHODS

We used qualitative methods with a dataset from a study conducted during 2019 with 31 active PWID residing in rural Puerto Rico. The study gathered ethnographic data and narratives about treatment trajectories to document the lived experiences of PWID as they moved in and out of treatment.

RESULTS

Participants were at least 18 years old; 87.7% were male, the mean age was 44.1 years, and the mean age at first injection was 22 years. Participants identified homelessness, lack of proper ID or other identifying documents, and previous negative experiences with MOUD as the main barriers to treatment entry and retention. In addition, PWID's belief that MOUD simply substitutes an illegal drug for a legal one, while furthering drug dependence by chronically subjecting patients to treatment, constitutes an additional barrier to entry. Findings from this study demonstrate that MOUD barriers to access and retention compound and are severely affected by poverty and other forms of vulnerability among PWID in rural Puerto Rico.

CONCLUSION

Policies to increase access and retention should consider barriers not in isolation but as an assemblage of many factors.

Cost-effectiveness of Direct Antiviral Agents for Hepatitis C Virus Infection and a Combined Intervention of Syringe Access and Medication-assisted Therapy for Opioid Use Disorders in an Injection Drug Use Population

BACKGROUND

There are too many plausible permutations and scale-up scenarios of combination hepatitis C virus (HCV) interventions for exhaustive testing in experimental trials. Therefore, we used a computer simulation to project the health and economic impacts of alternative combination intervention scenarios for people who inject drugs (PWID), focusing on direct antiviral agents (DAA) and medication-assisted treatment combined with syringe access programs (MAT+).

METHODS

We performed an allocative efficiency study, using a mathematical model to simulate the progression of HCV in PWID and its related consequences. We combined 2 previously validated simulations to estimate the cost-effectiveness of intervention strategies that included a range of coverage levels. Analyses were performed from a health-sector and societal perspective, with a 15-year time horizon and a discount rate of 3%.

RESULTS

From a health-sector perspective (excluding criminal justice system-related costs), 4 potential strategies fell on the cost-efficiency frontier. At 20% coverage, DAAs had an incremental cost-effectiveness ratio (ICER) of $27 251/quality-adjusted life-year (QALY). Combinations of DAA at 20% with MAT+ at 20%, 40%, and 80% coverage had ICERs of $165 985/QALY, $325 860/QALY, and $399 189/QALY, respectively. When analyzed from a societal perspective (including criminal justice system-related costs), DAA at 20% with MAT+ at 80% was the most effective intervention and was cost saving. While DAA at 20% with MAT+ at 80% was more expensive (eg, less cost saving) than MAT+ at 80% alone without DAA, it offered a favorable value compared to MAT+ at 80% alone ($23 932/QALY).

CONCLUSIONS

When considering health-sector costs alone, DAA alone was the most cost-effective intervention. However, with criminal justice system-related costs, DAA and MAT+ implemented together became the most cost-effective intervention.

"Caballo": risk environments, drug sharing and the emergence of a hepatitis C virus epidemic among people who inject drugs in Puerto Rico

BACKGROUND

Sharing drug injection equipment has been associated with the transmission of HCV among PWID through blood contained in the cooker and cotton used to prepare and divide up the drug solution. While epidemiologists often subsume this practice under the sharing of "ancillary equipment," more attention should be paid to the fact that indirect sharing takes place within the process of joint drug acquisition and preparation.

METHODS

We employed an ethnographic approach observing active PWID (N = 33) in four rural towns in Puerto Rico in order to document drug sharing arrangements involved in "caballo", as this practice is locally known. We explored partners' motivation to engage in drug sharing, as well as its social organization, social roles and existing norms.

FINDINGS

Findings suggest that drug sharing, is one of the main drivers of the HCV epidemic in this population. Lack of financial resources, drug packaging, drug of choice and the desire to avoid the painful effects of heroin withdrawal motivates participants' decision to partner with somebody else, sharing injection equipment-and risk-in the process. Roles are not fixed, changing not only according to caballo partners, but also, power dynamics.

CONCLUSION

In order to curb the HCV epidemic, harm reduction policies should recognize the particular sociocultural contexts in which people inject drugs and make decisions about risk. Avoiding sharing of injection equipment within an arrangement between PWID to acquire and use drugs is more complex than assumed by harm reduction interventions. Moving beyond individual risk behaviors, a risk environment approach suggest that poverty, and a strict drug policy that encourage users to carry small amounts of illicit substances, and a lack of HCV treatment among other factors, contribute to HCV transmission.

Competing forces of withdrawal and disease avoidance in the risk networks of people who inject drugs

We analyze a network of needle-sharing ties among 117 people who inject drugs (PWID) in rural Puerto Rico, using exponential random graph modeling to examine whether network members engage in partner restriction to lower their risk of contracting HIV or hepatitis C (HCV), or in informed altruism to prevent others from contracting these infections. Although sharing of used syringes is a significant risk factor for transmission of these diseases among PWID, we find limited evidence for partner restriction or informed altruism in the network of reported needle-sharing ties. We find however that sharing of needles is strongly reciprocal, and individuals with higher injection frequency are more likely to have injected with a used needle. Drawing on our ethnographic work, we discuss how the network structures we observe may relate to a decision-making rationale focused on avoiding withdrawal sickness, which leads to risk-taking behaviors in this poor, rural context where economic considerations often lead PWID to cooperate in the acquisition and use of drugs.

Injection Opioid and Injection Methamphetamine Use in the Rural United States: A Systematic Review and Network Analysis

The abuse of opioid and methamphetamine is a public health crisis in the United States, particularly in rural areas where injection drug use is common. This systematic review of rural injection drug use synthesized the research on injection of opioids and methamphetamine use and assessed the similarity of their research findings to the field of rural injection drug use in the United States. A citation network analysis was used to support the assessment of research similarity and provided a visualization of the field. This citation network analysis exposed a gap in the literature revealing that the state of research may not be fully applicable to the field in its entirety in the United States. In summary, this review provides a representative overview of the state of research in the field of injection drug use. Future research should conduct studies on rural drug use in areas of the country not represented in this review.

Migration to the US among rural Puerto Ricans who inject drugs: influential factors, sources of support, and challenges for harm reduction interventions

BACKGROUND

While PWID of Puerto Rican origin have been migrating to the US for decades, the range of factors influencing their migration to the US and the resources they draw on to do so are not well understood. This is particularly true for rural Puerto Rican PWID, and the present study is the first empirical research to document migration patterns among this population. The specificities of their migration raise important challenges that need to be documented in order to implement more effective harm reduction policies at home (Puerto Rico) and abroad (US).

METHODS

This paper draws from data obtained employing a modified NHBS survey which was administered to (N =296) PWID in four rural municipalities of Puerto Rico with participants 18 years or older. The primary dependent variables for this paper are the number of times a person has lived in the continental US, and if they are planning on moving to the continental US in the future.

RESULTS

Findings suggest that 65% of the sample reported ever lived in the US and that 49% are planning on moving in the future. The number of times living in the US is associated with higher education and older age, but not with self-reported positive HIV or HCV statuses. Planning to move to the US is associated with knowing PWID who have moved or plan to move, negatively associated with age, and is not associated with HIV or HCV status. Around one third of those that lived in the US reported having some sort of support, with the majority receiving support from family sources. No participant received help to enter HIV/HCV treatment.

CONCLUSIONS

A multi-region approach to prevention is required to make a dent in curbing HIV/HCV transmission in this population. Understanding PWID migration patterns, risk behaviors, and health care needs in the US is now more important than ever as natural disasters prompted by human-made climate change will only increase in the future, raising demands not only for service providers but also harm reduction policies to cope with an increasing influx of "climate refugees" as PWID move across national borders.

Community mobilization for rural suicide prevention: Process, learning and behavioral outcomes from Promoting Community Conversations About Research to End Suicide (PC CARES) in Northwest Alaska

RATIONALE

This study evaluates the process and preliminary outcomes of Promoting Community Conversations About Research to End Suicide (PC CARES), an intervention that brings key stakeholders together so they can discuss suicide prevention research and find ways to put it into practice. Originally piloted in remote and rural Alaskan communities, the approach shows promise.

METHOD

Using a multi-method design, the study describes a series of locally-facilitated "learning circles" over 15 months and their preliminary results. Sign-in sheets documented participation. Transcriptions of audio-recorded sessions captured facilitator fidelity, accuracy, and the dominant themes of community discussions. Linked participant surveys (n=83) compared attendees' perceived knowledge, skills, attitudes, and their 'community of practice' at baseline and follow-up. A cross-sectional design compared 112 participants' with 335 non-participants' scores on knowledge and prevention behaviors, and considered the social impact with social network analyses.

RESULTS

Demonstrating feasibility in small rural communities, local PC CARES facilitators hosted 59 two to three hour learning circles with 535 participants (376 unique). Local facilitators achieved acceptable fidelity to the model (80%), and interpreted the research accurately 81% of the time. Discussions reflected participants' understanding of the research content and its use in their lives. Participants showed positive changes in perceived knowledge, skills, and attitudes and strengthened their 'community of practice' from baseline to follow-up. Social network analyses indicate PC CARES had social impact, sustaining and enhancing prevention activities of non-participants who were 'close to' participants. These close associates were more likely take preventive actions than other non-participants after the intervention.

CONCLUSION

PC CARES offers a practical, scalable method for community-based translation of research evidence into selfdetermined, culturally-responsive suicide prevention practice.

Prevalence and Risk Factors associated with Homelessness among Drug Users in Puerto Rico

OBJECTIVE

This study aimed to determine the association between years of drug injection and homelessness among drug users in rural Puerto Rico.

METHODS

Respondent-driven sampling methods allowed us to obtain a sample of 315 intravenous drug users (IDUs) in rural Puerto Rico. Information about sociodemographic characteristics, drug use patterns, homelessness and risk behaviors was obtained through structured interviews. HIV and HCV statuses were assessed via rapid antibody tests. Frequency distributions were used to describe the study sample. Bivariate analysis and multivariate logistic regressions were used to assess covariates of homelessness. The study received IRB approval through the University of Nebraska-Lincoln and the University of Puerto Rico.

RESULTS

Almost 91% of the study participants were males. The mean age was 41.7 years and the majority of the participants had not completed high school (47.6%). The prevalence of current homelessness was 21.9%. After controlling for sociodemographic characteristics, homelessness was strongly associated with the number of years of injection drug use. The odds of being homeless for IDUs with 21 years or more of drug injection was almost 3 times higher than were the odds of being homeless for IDUs with fewer than 10 years of injection (OR = 2.58 95%; CI=1.21,5.48).

CONCLUSION

In rural Puerto Rico, the prevalence of current homelessness in IDUs was 21.7%. In the sample, 6.0% were HIV positive and 78.4% were HCV positive. Our results highlight the necessity of increasing accessibility to substance abuse treatment and establishing additional needle-exchange programs (currently, there is only 1) in rural Puerto Rico.

Combination interventions for Hepatitis C and Cirrhosis reduction among people who inject drugs: An agent-based, networked population simulation experiment

Hepatitis C virus (HCV) infection is endemic in people who inject drugs (PWID), with prevalence estimates above 60% for PWID in the United States. Previous modeling studies suggest that direct acting antiviral (DAA) treatment can lower overall prevalence in this population, but treatment is often delayed until the onset of advanced liver disease (fibrosis stage 3 or later) due to cost. Lower cost interventions featuring syringe access (SA) and medically assisted treatment (MAT) have shown mixed results in lowering HCV rates below current levels. However. little is known about the potential cumulative effects of combining DAA and MAT treatment. While simulation experiments can reveal likely long-term effects, most prior simulations have been performed on closed populations of model agents—a scenario quite different from the open, mobile populations known to most health agencies. This paper uses data from the Centers for Disease Control’s National HIV Behavioral Surveillance project, IDU round 3, collected in New York City in 2012 to parameterize simulations of open populations. To test the effect of combining DAA treatment with SA/MAT participation, multiple, scaled implementations of the two intervention strategies were simulated. Our results show that, in an open population, SA/MAT by itself has only small effects on HCV prevalence, while DAA treatment by itself can lower both HCV and HCV-related advanced liver disease prevalence. More importantly, the simulation experiments suggest that combinations of the two strategies can, when implemented together and at sufficient levels, dramatically reduce HCV incidence. We conclude that adopting SA/MAT implementations alongside DAA interventions can play a critical role in reducing the long-term consequences of ongoing HCV infection.

Mapping the structure of perceptions in helping networks of Alaska Natives

This paper introduces a new method for acquiring and interpreting data on cognitive (or perceptual) networks. The proposed method involves the collection of multiple reports on randomly chosen pairs of individuals, and statistical means for aggregating these reports into data of conventional sociometric form. We refer to the method as "perceptual tomography" to emphasize that it aggregates multiple 3rd-party data on the perceived presence or absence of individual properties and pairwise relationships. Key features of the method include its low respondent burden, flexible interpretation, as well as its ability to find "robust intransitive" ties in the form of perceived non-edges. This latter feature, in turn, allows for the application of conventional balance clustering routines to perceptual tomography data. In what follows, we will describe both the method and an example of the implementation of the method from a recent community study among Alaska Natives. Interview data from 170 community residents is used to ascribe 4446 perceived relationships (2146 perceived edges, 2300 perceived non-edges) among 393 community members, and to assert the perceived presence (or absence) of 16 community-oriented helping behaviors to each individual in the community. Using balance theory-based partitioning of the perceptual network, we show that people in the community perceive distinct helping roles as structural associations among community members. The fact that role classes can be detected in network renderings of "tomographic" perceptual information lends support to the suggestion that this method is capable of producing meaningful new kinds of data about perceptual networks.

Agency and social constraint among victims of domestic minor sex trafficking: A method for measuring free will

Human agency has been a focus of philosophical and sociological concern from early debates about "free will" to recent themes in poststructuralism. Debates over the proper understanding of structure, agency, and constraint are hindered by the fact that few if any empirical measures of these concepts have been proposed. As sociologists have long recognized, the total results of the decisions of a group's members can be viewed as a distribution, and parameters can be fit to obtain a description of observed distributions. Here we propose the use of negative binomial curve to model population survival outcomes, and suggest that the parameters of such a curve represent reasonable surrogates for measures of agency, opportunity, and constraint when the decision process can be thought of as akin to a Bernoulli process. To provide an illustration of this approach, we discuss participation of legal minors in commercial sex (commonly referred to as victims of domestic minor sex trafficking (VDMST) or commercially sexually exploited children (CSEC)). In popular and advocacy-based accounts, considerable focus has been placed on the relative powerlessness of female VDMST. Using the proposed modeling technique, we test the extent to which male versus female VDMST appear to possess greater agency (or function under more limiting constraint) when deciding whether to remain in sex work or "leave the life". Contrary to existing literature, our results indicate that male and female underage sex workers are experiencing similar levels of agency, and differ mainly in opportunity, and constraint. Other individual circumstances are shown to contribute to varying levels of agency and constraint among sex workers, including street work status, community trouble, drug use, and the availability of an alternative income.

Rural and Urban Differences in Nebraskans’ Access to Marijuana, Methamphetamine, Heroin, and Prescription Pills

The ability of a user to access a given type of drug is related to the configuration of the market for that drug, and a range of economic and criminal justice concerns. This study focuses on Nebraskan’s “ready access” to four types of drugs (marijuana, methamphetamine, heroin, and prescription pills) in 2016, using a statewide survey of housed Nebraskan adults. Ready access is defined as a participant knowing at least one person from whom they could obtain a given type of drug if they wanted to. We found that 35% of adult Nebraskans knew at least one person from whom they could obtain marijuana, 8.9% for methamphetamine, 4.5% for heroin, and 17.8% knew at least one source for prescription pills. Relationships between knowing a source for each type of drug and rurality, sex, race, religious attendance, mental health symptoms, and education are explored.

Injection Partners, HCV, and HIV Status among Rural Persons Who Inject Drugs in Puerto Rico

BACKGROUND

The prevalence of hepatitis C (HCV) and HIV among persons who inject drugs (PWID) and the ability of these diseases to spread through injection networks are well documented in urban areas. However, less is known about injection behaviors in rural areas.

OBJECTIVES

This study focuses on the association between the number of self-reported injection partners with the PWID's self-reported HCV and HIV status. Injection networks provide paths for infection and information to flow, and are important to consider when developing prevention and intervention strategies.

METHODS

Respondent driven sampling was used to conduct 315 interviews with PWID in rural Puerto Rico during 2015. Negative binomial regression was used to test for associations between the number of self-reported injection partners and self-reported HCV and HIV statuses. Multinomial logistic regression was used to test for associations with the participant's self-reported HCV and HIV statuses.

RESULTS

Self-reported HCV status is significantly associated with injection risk network size. Injection partner networks of self-reported HCV- respondents are half what is reported by those with a positive or unknown status. Self-reported HIV statuses are not associated with different numbers of injection partners.

CONCLUSIONS

Smaller injection networks among those who self-report a HCV- status suggests that those who believe their status to be negative may take protective action by reducing their injection network compared to those have a self-reported HCV+ or an unknown status. Although the cross-sectional design of the study makes it difficult verify, such behavior has implications for prevention programs attempting to prevent HCV transmission.

Latent Risk Subtypes Based on Injection and Sexual Behavior Among People Who Inject Drugs in Rural Puerto Rico

BACKGROUND

People who inject drugs (PWID) in Puerto Rico engage in high levels of injection and sexual risk behavior, and they are at high risk for HIV and hepatitis C (HCV) infection, relative to their US counterparts. Less is known, however, about the clustering of risk behavior conducive to HIV and HCV infection among rural Puerto Rican communities.

OBJECTIVES

The purpose of this study was to examine concurrent injection and sexual risk subtypes among a rural sample of PWID in Puerto Rico.

METHODS

Data were drawn from a respondent-driven sample collected in 2015 of 315 PWID in 4 rural communities approximately 30-40 miles from San Juan. Latent class analysis (LCA) was used to examine risk subtypes using 3 injection and 3 sexual risk indicators. In addition, demographic and other PWID characteristics were examined as possible predictors of latent class membership.

RESULTS

Four LCA subtypes were identified: low risk (36%), high injection/low sexual risk (22%), low injection/high sexual risk (20%), and high risk (22%). Younger age and past year homelessness predicted high risk latent class membership, relative to the other classes. In addition, daily speedball use predicted membership in the high injection/low sexual risk class, relative to the low risk and low injection/high sexual risk classes.

CONCLUSION/IMPORTANCE

The findings suggest ways in which PWID risk clusters can be identified for targeted interventions.

One-step estimation of networked population size: Respondent-driven capture-recapture with anonymity

Size estimation is particularly important for populations whose members experience disproportionate health issues or pose elevated health risks to the ambient social structures in which they are embedded. Efforts to derive size estimates are often frustrated when the population is hidden or hard-to-reach in ways that preclude conventional survey strategies, as is the case when social stigma is associated with group membership or when group members are involved in illegal activities. This paper extends prior research on the problem of network population size estimation, building on established survey/sampling methodologies commonly used with hard-to-reach groups. Three novel one-step, network-based population size estimators are presented, for use in the context of uniform random sampling, respondent-driven sampling, and when networks exhibit significant clustering effects. We give provably sufficient conditions for the consistency of these estimators in large configuration networks. Simulation experiments across a wide range of synthetic network topologies validate the performance of the estimators, which also perform well on a real-world location-based social networking data set with significant clustering. Finally, the proposed schemes are extended to allow them to be used in settings where participant anonymity is required. Systematic experiments show favorable tradeoffs between anonymity guarantees and estimator performance. Taken together, we demonstrate that reasonable population size estimates are derived from anonymous respondent driven samples of 250-750 individuals, within ambient populations of 5,000-40,000. The method thus represents a novel and cost-effective means for health planners and those agencies concerned with health and disease surveillance to estimate the size of hidden populations. We discuss limitations and future work in the concluding section.

Injection-related hepatitis C serosorting behaviors among people who inject drugs: An urban/rural comparison

Although previous research has focused on injection drug use behaviors in both urban and rural settings, few have drawn direct comparisons between adjacent rural and urban areas. Using data from the National HIV Behavioral Surveillance study as well as original data collected in a similar fashion, we compare the risk behaviors of people who inject drugs (PWID) in San Juan, Puerto Rico, with those of PWID in nearby rural areas. Specifically, we examine whether one's own hepatitis C (HCV) infection status can be used to predict whether one asked their most recent co-injection partner about their HCV status. Acquiring such information allows injectors to seek out co-injection partners of concordant status as a way to minimize the risk of viral transmission. Results indicate that urban PWID with a known HCV+ status were more likely to know their last co-injector partner's HCV status than were their peers with a negative or unknown HCV status. However, this relationship was not present in the rural data. These findings suggest that there are different risk norms in rural and urban PWID communities and that interventions successful in one type of community may not be so in others.

"It Ruined My Life": The effects of the War on Drugs on people who inject drugs (PWID) in rural Puerto Rico

BACKGROUND

The War on Drugs has raised the incarceration rates of racial minorities for non-violent drug-related crimes, profoundly stigmatized drug users, and redirected resources from drug prevention and treatment to militarizing federal and local law enforcement. Yet, while some states consider shifting their punitive approach to drug use, to one based on drug treatment and rehabilitation, nothing suggests that these policy shifts are being replicated in Puerto Rico.

METHODS

This paper utilizes data from 360 PWID residing in four rural towns in the mountainous area of central Puerto Rico. We initially recruited 315 PWID using respondent-driven sampling (RDS) and collected data about risk practices and conducted HIV and HCV testing. During a second phase, we conducted 34 micro-ethnographic assays, in which we randomly recruited 34 participants from the first phase and included their ego networks in this phase. Our ethnographic inquiry produced significant data regarding the effects of the war on drugs on the local drug trade, drug availability, and injectors' social networks.

RESULTS

Findings suggest that repressive policing has been ineffective in preventing drug distribution and use among those in our study. This type of law enforcement approach has resulted in the disproportionate incarceration of poor drug users in rural Puerto Rico, and mainly for nonviolent drug-related crimes. In addition, incarceration exposes PWID to a form of a cruel and unusual punishment: having to quit heroin "cold turkey" while the prison environment also represents a HIV/HCV risk. In turn, the war on drugs not only diverts resources from treatment but also shapes treatment ideologies, punishing non-compliant patients.

CONCLUSION

Shifting the emphasis from repression to treatment and rehabilitation is likely to have a positive impact on the health and overall quality of life of PWID and their communities.

Rural and urban comparisons of polysubstance use profiles and associated injection behaviors among people who inject drugs in Puerto Rico

INTRODUCTION

In contrast to urban populations, little is known about polysubstance use among rural people who inject drugs (PWID), particularly in Puerto Rico where injection drug use and related health consequences are prevalent. The aim of the study is to compare injection and non-injection substance use profiles among separate urban and rural samples of Puerto Rican PWID.

MATERIAL AND METHODS

Data for the urban sample come from 455 PWID who participated in the CDC's National HIV Behavioral Surveillance survey of injection drug use in San Juan. The data for the rural sample come from 315 PWID residing in four rural cities approximately 40-miles from San Juan. Latent class analysis was used to derive separate urban and rural profiles of weekly injection and non-injection substance use. Injection behaviors were examined as possible correlates of latent class membership.

RESULTS

Five latent classes were identified in the urban sample, and three latent classes were identified in the rural sample. Classes were similar across samples; however, key differences emerged. Both samples had classes of primary heroin injectors, primary speedball injectors, and cocaine-heroin injectors. The urban sample had one high polysubstance class. Polysubstance use profiles that shared similar characteristics between samples also shared similar injection patterns, with some variation.

DISCUSSION

Variations in substance use patterns and associated health risks are likely shaped by social and geographic boundaries.

CONCLUSIONS

Understanding variations in substance use patterns across rural and urban locales may improve surveillance efforts and tailor desistance and harm reduction efforts at the state and local levels.

Bi-cultural dynamics for risk and protective factors for cardiometabolic health in an Alaska Native (Yup'ik) population

Alaska Native people experience disparities in mortality from heart disease and stroke. This work attempts to better understand the relationships between socioeconomic, behavioral, and cardiometabolic risk factors among Yup'ik people of southwestern Alaska, with a focus on the role of the socioeconomic, and cultural components. Using a cross-sectional sample of 486 Yup'ik adults, we fitted a Partial Least Squares Path Model (PLS-PM) to assess the associations between components, including demographic factors [age and gender], socioeconomic factors [education, economic status, Yup'ik culture, and Western culture], behavioral factors [diet, cigarette smoking and smokeless tobacco use, and physical activity], and cardiometabolic risk factors [adiposity, triglyceride-HDL and LDL lipids, glycemia, and blood pressure]. We found relatively mild associations of education and economic status with cardiometabolic risk factors, in contrast with studies in other populations. The socioeconomic factor and participation in Yup'ik culture had potentially protective associations with adiposity, triglyceride-HDL lipids, and blood pressure, whereas participation in Western culture had a protective association with blood pressure. We also found a moderating effect of participation in Western culture on the relationships between Yup'ik culture participation and both blood pressure and LDL lipids, indicating a potentially beneficial additional effect of bi-culturalism. Our results suggest that reinforcing protective effects of both Yup'ik and Western cultures could be useful for interventions aimed at reducing cardiometabolic health disparities.

Needle acquisition patterns, network risk and social capital among rural PWID in Puerto Rico

BACKGROUND

People who inject drugs (PWID) take on significant risks of contracting blood-borne infection, including injecting with a large number of partners and acquiring needles from unsafe sources. When combined, risk of infection can be magnified.

METHODS

Using a sample of PWID in rural Puerto Rico, we model the relationship between a subject's number of injection partners and the likelihood of having used an unsafe source of injection syringes. Data collection with 315 current injectors identified six sources of needles.

RESULTS

Of the six possible sources, only acquisition from a seller (paid or free), or using syringes found on the street, was significantly related to number of partners.

CONCLUSIONS

These results suggest that sources of syringes do serve to multiply risk of infection caused by multi-partner injection concurrency. They also suggest that prior research on distinct forms of social capital among PWID may need to be rethought.

Rural and urban injection drug use in Puerto Rico: Network implications for human immunodeficiency virus and hepatitis C virus infection

Understanding the short- and long-term transmission dynamics of blood-borne illnesses in network contexts represents an important public health priority for people who inject drugs and the general population that surrounds them. The purpose of this article is to compare the risk networks of urban and rural people who inject drugs in Puerto Rico. In the current study, network characteristics are drawn from the sampling "trees" used to recruit participants to the study. We found that injection frequency is the only factor significantly related to clustering behavior among both urban and rural people who inject drugs.

The Interaction of Risk Network Structures and Virus Natural History in the Non-spreading of HIV Among People Who Inject Drugs in the Early Stages of the Epidemic

This article explores how social network dynamics may have reduced the spread of HIV-1 infection among people who inject drugs during the early years of the epidemic. Stochastic, discrete event, agent-based simulations are used to test whether a "firewall effect" can arise out of self-organizing processes at the actor level, and whether such an effect can account for stable HIV prevalence rates below population saturation. Repeated simulation experiments show that, in the presence of recurring, acute, and highly infectious outbreaks, micro-network structures combine with the HIV virus's natural history to reduce the spread of the disease. These results indicate that network factors likely played a significant role in the prevention of HIV infection within injection risk networks during periods of peak prevalence. They also suggest that social forces that disturb network connections may diminish the natural firewall effect and result in higher rates of HIV.

Hepatitis C serosorting among people who inject drugs in rural Puerto Rico

Due to the high cost of treatment, preventative measures to limit Hepatitis C (HCV) transmission among people who inject drugs (PWID) are encouraged by many public health officials. A key one of these is serosorting, where PWID select risk partners based on concordant HCV status. Research on the general U.S. population by Smith et al. (2013) found that knowledge of one's own HCV status facilitated serosorting behaviors among PWID, such that respondents with knowledge of their own status were more likely to ask potential partners about their status prior to sharing risk. Our objective was to see if this held true in rural Puerto Rico. We replicate this study using a sample of PWID in rural Puerto Rico to draw comparisons. We used respondent driven sampling to survey 315 participants, and have a final analytic sample of 154. The survey was heavily modeled after the National HIV Behavioral Survey, which was the dataset used by the previous researchers. We found that among PWID in rural Puerto Rico, unlike in the general population, knowledge of one's own HCV status had no significant effect on the selection of one's most recent injection partner, based on his/her HCV status. We conclude that PWID in rural Puerto Rico differ from the general U.S. population when it comes to serosorting behaviors, and that these differences should be taken into account in future outreaches and intervention strategies.

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Recent study finds PWID ask potential partners about infections once own status known.

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We replicate this using similar measures with a sample in rural Puerto Rico.

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Find no evidence this happens in rural Puerto Rico, though women more likely to ask.

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Null finding may be due to small sample size, but pattern still appears unique.

Differential access to syringe exchange and other prevention activities among people who inject drugs in rural and urban areas of Puerto Rico

BACKGROUND

Injection drug use and its associated blood-borne infections has become a rapidly increasing problem in rural areas of the US recently. Syringe exchange programs have been shown to be effective for reducing transmission of blood borne infections, however access to these prevention efforts may be limited in rural areas.

METHODS

This paper utilizes two separate community samples of people who inject drugs (PWID) in Puerto Rico to achieve the following research objectives: (1) compare rural and urban access to syringe exchange programs, free sterile syringes and other HIV/HCV prevention activities, and (2) examine whether utilization of prevention activities is associated with lower injection risk behaviors. Two samples were recruited with RDS (n=315 rural sample; n=512 urban sample) and included adults aged 18 years and older who have injected drugs within the past month.

RESULTS

78.5% of the urban sample utilized a syringe exchange program in the past year, compared to 58.4% of the rural sample (p<.001). 71.4% of the urban sample received free sterile needles, compared to 58.4% of the rural sample (p<.001). 66% of the urban sample received free works compared to 59% of the rural sample (p=.034). 29% of urban PWID had a conversation with an outreach worker about HIV prevention compared to 18% of the rural sample (p<0.001). Receiving free needles significantly increases the frequency of using a sterile needle to inject (p<.001).

CONCLUSION

Urban PWID were significantly more likely to have utilized syringe exchange programs, received free sterile needles, received free works, and to have talked about HIV prevention with an outreach worker during the past year than PWID residing in rural areas. Individuals who accessed these prevention activities were significantly less likely to exhibit risky injection behavior. Policy implications call for increasing access to prevention services in rural areas to reduce disease transmission.

Social Determinants of HIV/HCV Co-Infection: A case Study from People Who Inject Drugs in Rural Puerto Rico

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Co-infection correlates with age, longer period of drug use, medical insurance coverage and sexual identity.

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LGBT PWID are vulnerable to co-infection. Stigma, commercial sex and violence compounds risk.

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Culturally sensitive prevention strategies focused on this particular population should be implemented to avoid co-infection.

Attractor-Based Obstructions to Growth in Homogeneous Cyclic Boolean Automata

We consider a synchronous Boolean organism consisting of N cells arranged in a circle, where each cell initially takes on an independently chosen Boolean value. During the lifetime of the organism, each cell updates its own value by responding to the presence (or absence) of diversity amongst its two neighbours' values. We show that if all cells eventually take a value of 0 (irrespective of their initial values) then the organism necessarily has a cell count that is a power of 2. In addition, the converse is also proved: if the number of cells in the organism is a proper power of 2, then no matter what the initial values of the cells are, eventually all cells take on a value of 0 and then cease to change further. We argue that such an absence of structure in the dynamical properties of the organism implies a lack of adaptiveness, and so is evolutionarily disadvantageous. It follows that as the organism doubles in size (say from m to 2m) it will necessarily encounter an intermediate size that is a proper power of 2, and suffers from low adaptiveness. Finally we show, through computational experiments, that one way an organism can grow to more than twice its size and still avoid passing through intermediate sizes that lack structural dynamics, is for the organism to depart from assumptions of homogeneity at the cellular level.

Network Approaches to Substance Use and HIV/Hepatitis C Risk among Homeless Youth and Adult Women in the United States: A Review

During the United States economic recession of 2008-2011, the number of homeless and unstably housed people in the United States increased considerably. Homeless adult women and unaccompanied homeless youth make up the most marginal segments of this population. Because homeless individuals are a hard to reach population, research into these marginal groups has traditionally been a challenge for researchers interested in substance abuse and mental health. Network analysis techniques and research strategies offer means for dealing with traditional challenges such as missing sampling frames, variation in definitions of homelessness and study inclusion criteria, and enumeration/population estimation procedures. This review focuses on the need for, and recent steps toward, solutions to these problems that involve network science strategies for data collection and analysis. Research from a range of fields is reviewed and organized according to a new stress process framework aimed at understanding how homeless status interacts with issues related to substance abuse and mental health. Three types of network innovation are discussed: network scale-up methods, a network ecology approach to social resources, and the integration of network variables into the proposed stress process model of homeless substance abuse and mental health. By employing network methods and integrating these methods into existing models, research on homeless and unstably housed women and unaccompanied young people can address existing research challenges and promote more effective intervention and care programs.

Understanding differences in HIV/HCV prevalence according to differentiated risk behaviors in a sample of PWID in rural Puerto Rico

BACKGROUND

Blood contained in needles and injection equipment has been identified as a vector for HIV and HCV transmission among people who inject drugs (PWID). Yet, there is often a wide discrepancy in prevalence for both viruses. While microbiological differences between viruses influence prevalence, other variables associated with the way drugs are acquired and used, also play a role.

METHODS

Respondent-driven sampling (RDS) methods recruited a sample of 315 current intravenous drug users in rural Puerto Rico. Information about type and frequency of use, HIV and HVC risk behaviors (sharing needles, cookers, cotton, and water), sexual behaviors, and alcohol use was collected. HIV and HCV statuses were assessed via rapid antibody tests. T tests compare means of participants who tested positive (reactive) to those who tested negative. Logistic regression analyses were used to validate the association of the risk factors involved.

RESULTS

Tests showed a significant difference in HIV (6%) and HCV (78.4%) prevalence among a population of current PWID. The main risk behaviors in HCV transmission are the sharing of injection "works", (e.g., cookers, cotton, and water). Sharing works occurred more than twice as often as the sharing of needles, and HCV+ and HCV- individuals reported the same needle sharing habits.

CONCLUSIONS

Washing and rinsing injection works with water seems to prevent HIV transmission, but it is unable to prevent HCV infection. While education about the need to clean injection equipment with bleach might be beneficial, equipment sharing--and the subsequent risk of HVC--might be unavoidable in a context where participants are forced to pool resources to acquire and use intravenous drugs.

Creating a Community of Practice to Prevent Suicide Through Multiple Channels: Describing the Theoretical Foundations and Structured Learning of PC CARES

It is critical to develop practical, effective, ecological, and decolonizing approaches to indigenous suicide prevention and health promotion for the North American communities. The youth suicide rates in predominantly indigenous small, rural, and remote Northern communities are unacceptably high. This health disparity, however, is fairly recent, occurring over the last 50 to 100 years as communities experienced forced social, economic, and political change and intergenerational trauma. These conditions increase suicide risk and can reduce people's access to shared protective factors and processes. In this context, it is imperative that suicide prevention includes--at its heart--decolonization, while also utilizing the "best practices" from research to effectively address the issue from multiple levels. This article describes such an approach: Promoting Community Conversations About Research to End Suicide (PC CARES). PC CARES uses popular education strategies to build a "community of practice" among local and regional service providers, friends, and families that fosters personal and collective learning about suicide prevention in order to spur practical action on multiple levels to prevent suicide and promote health. This article will discuss the theoretical underpinnings of the community intervention and describe the form that PC CARES takes to structure ongoing dialogue, learning, solidarity, and multilevel mobilization for suicide prevention.

Current Rural Drug Use in the US Midwest

The nature and challenge of illicit drug use in the United States continues to change rapidly, evolving in reaction to myriad social, economic, and local forces. While the use of illicit drugs affects every region of the country, most of our current information about drug use comes from large urban areas. Data on rural drug use and its harms justify greater attention. Record overdose rates, unexpected outbreaks of HIV, and a dearth of treatment facilities point to a rapidly worsening health situation. While health sciences have made considerable progress in understanding the etiology of drug use and uncovering the link between drug use and its myriad associated harms, this promising scientific news has not always translated to better health outcomes. The scope of the problem in the Central Plains of the US is growing, and can be estimated from available sources. Clear remedies for this rising level of abuse are available, but few have been implemented. Suggestions for short-term policy remedies are discussed.

Improving the Network Scale-Up Estimator: Incorporating Means of Sums, Recursive Back Estimation, and Sampling Weights

Researchers interested in studying populations that are difficult to reach through traditional survey methods can now draw on a range of methods to access these populations. Yet many of these methods are more expensive and difficult to implement than studies using conventional sampling frames and trusted sampling methods. The network scale-up method (NSUM) provides a middle ground for researchers who wish to estimate the size of a hidden population, but lack the resources to conduct a more specialized hidden population study. Through this method it is possible to generate population estimates for a wide variety of groups that are perhaps unwilling to self-identify as such (for example, users of illegal drugs or other stigmatized populations) via traditional survey tools such as telephone or mail surveys—by asking a representative sample to estimate the number of people they know who are members of such a “hidden” subpopulation. The original estimator is formulated to minimize the weight a single scaling variable can exert upon the estimates. We argue that this introduces hidden and difficult to predict biases, and instead propose a series of methodological advances on the traditional scale-up estimation procedure, including a new estimator. Additionally, we formalize the incorporation of sample weights into the network scale-up estimation process, and propose a recursive process of back estimation “trimming” to identify and remove poorly performing predictors from the estimation process. To demonstrate these suggestions we use data from a network scale-up mail survey conducted in Nebraska during 2014. We find that using the new estimator and recursive trimming process provides more accurate estimates, especially when used in conjunction with sampling weights.

Predictors of Police Reporting Among Hispanic Immigrant Victims of Violence

The purpose of this study was to examine predictors of police reporting among Hispanic immigrant victims of violence. A sample of 127 Hispanic immigrants was generated through a chain-referral procedure in the city of Hempstead, New York. Participants were asked about their most recent victimization experiences, and detailed information was collected on up to three incidents. The analyses were based on a total of 214 separate victimization incidents, one third of which were reported to the police. Logistic regression analyses indicated that serious injury, multiple-victim incidents, and perceptions of discrimination increase the odds of a police report. Moreover, incidents involving a Black primary assailant were less likely to be reported to the police than incidents involving an assailant perceived to be of Hispanic origin. Supplementary analyses suggested that this latter relationship may be contingent upon the type of crime and the victim's relationship with the assailant. At the policy level, these findings call into question assumptions about very recent immigrants being too socially isolated and distrustful of law enforcement to sustain robust reporting levels, as well as pointing to encouraging possibilities for productive engagement between police and Hispanic immigrant populations.

Estimating Vertex Measures in Social Networks by Sampling Completions of RDS Trees

This paper presents a new method for obtaining network properties from incomplete data sets. Problems associated with missing data represent well-known stumbling blocks in Social Network Analysis. The method of “estimating connectivity from spanning tree completions” (ECSTC) is specifically designed to address situations where only spanning tree(s) of a network are known, such as those obtained through respondent driven sampling (RDS). Using repeated random completions derived from degree information, this method forgoes the usual step of trying to obtain final edge or vertex rosters, and instead aims to estimate network-centric properties of vertices probabilistically from the spanning trees themselves. In this paper, we discuss the problem of missing data and describe the protocols of our completion method, and finally the results of an experiment where ECSTC was used to estimate graph dependent vertex properties from spanning trees sampled from a graph whose characteristics were known ahead of time. The results show that ECSTC methods hold more promise for obtaining network-centric properties of individuals from a limited set of data than researchers may have previously assumed. Such an approach represents a break with past strategies of working with missing data which have mainly sought means to complete the graph, rather than ECSTC's approach, which is to estimate network properties themselves without deciding on the final edge set.

Respondent-driven sampling to assess outcomes of sexual violence: a methodological assessment

Sexual violence is pervasive in eastern Democratic Republic of Congo (DRC). Survivors of sexual violence encounter numerous challenges, and women with a sexual violence-related pregnancy (SVRP) face even more complex sequelae. Because of the stigma associated with SVRP, there is no conventional sampling frame and, therefore, a paucity of research on SVRP outcomes. Respondent-driven sampling (RDS), used to study this "hidden" population, uses a peer recruitment sampling system that maintains strict participant privacy and controls and tracks recruitment. If RDS assumptions are met and the sample attains equilibrium, sample weights to correct for biases associated with traditional chain referral sampling can be calculated. Questionnaires were administered to female participants who were raising a child from a SVRP and/or who terminated a SVRP. A total of 852 participants were recruited from October 9, 2012, to November 7, 2012. There was rapid recruitment, and there were long referral chains. The majority of the variables reached equilibrium; thus, trends established in the sample population reflected the target population's trends. To our knowledge, this is the first study to use RDS to study outcomes of sexual violence. RDS was successfully applied to this population and context and should be considered as a sampling methodology in future sexual violence research.

A stochastic agent-based model of pathogen propagation in dynamic multi-relational social networks

We describe a general framework for modeling and stochastic simulation of epidemics in realistic dynamic social networks, which incorporates heterogeneity in the types of individuals, types of interconnecting risk-bearing relationships, and types of pathogens transmitted across them. Dynamism is supported through arrival and departure processes, continuous restructuring of risk relationships, and changes to pathogen infectiousness, as mandated by natural history; dynamism is regulated through constraints on the local agency of individual nodes and their risk behaviors, while simulation trajectories are validated using system-wide metrics. To illustrate its utility, we present a case study that applies the proposed framework towards a simulation of HIV in artificial networks of intravenous drug users (IDUs) modeled using data collected in the Social Factors for HIV Risk survey.

Hepatitis C virus infection among HIV-positive men who have sex with men: protocol for a systematic review and meta-analysis

BACKGROUND

Outbreaks of hepatitis C virus (HCV) infection have been reported in HIV-positive men who have sex with men (MSM) in North America, Europe and Asia. Transmission is believed to be the result of exposure to blood during sexual contact. In those infected with HIV, acute HCV infection is more likely to become chronic, treatment for both HIV and HCV is more complicated and HCV disease progression may be accelerated. There is a need for systematic reviews and meta-analyses to synthesize the epidemiology, prevention and methods to control HCV infection in this population.

METHODS/DESIGN

Eligible studies will include quantitative empirical data related to sexual transmission of HCV in HIV-positive MSM, including data describing incidence or prevalence, and associations between risk factors or interventions and the occurrence or progression of HCV disease. Care will be taken to ensure that HCV transmission related to injection drug use is excluded from the incidence estimates. Scientific databases will be searched using a comprehensive search strategy. Proceedings of scientific conferences, reference lists and personal files will also be searched. Quality ratings will be assigned to each eligible report using the Newcastle-Ottawa scale. Pooled estimates of incidence rates and measures of association will be calculated using random effects models. Heterogeneity will be assessed at each stage of data synthesis.

DISCUSSION

HIV-positive MSM are a key HCV-affected population in the US and other high-income countries. This review seeks to identify modifiable risk factors and settings that will be the target of interventions, and will consider how to constitute a portfolio of interventions to deliver the greatest health benefit. This question must be considered in relation to the magnitude of HCV infection and its consequences in other key affected populations, namely, young prescription opioid users who have transitioned to illicit opiate injection, and older injection drug users among whom HCV prevalence and incidence are extremely high. This review is part of a series of systematic reviews and meta-analyses that will synthesize the evidence across all these population groups and develop recommendations and decision tools to guide public health resource allocation.

TRIAL REGISTRATION

PROSPERO registration number: CRD42013006462.

A reexamination of connectivity trends via exponential random graph modeling in two IDU risk networks

Patterns of risk in injecting drug user (IDU) networks have been a key focus of network approaches to HIV transmission histories. New network modeling techniques allow for a reexamination of these patterns with greater statistical accuracy and the comparative weighting of model elements. This paper describes the results of a reexamination of network data from the SFHR and P90 data sets using Exponential Random Graph Modeling. The results show that "transitive closure" is an important feature of IDU network topologies, and provides relative importance measures for race/ethnicity, age, gender, and number of risk partners in predicting risk relationships.

Network Firewall Dynamics and the Subsaturation Stabilization of HIV

In 2001, Friedman et al. conjectured the existence of a "firewall effect" in which individuals who are infected with HIV, but remain in a state of low infectiousness, serve to prevent the virus from spreading. To evaluate this historical conjecture, we develop a new graph-theoretic measure that quantifies the extent to which Friedman's firewall hypothesis(FH)holds in a risk network. We compute this new measure across simulated trajectories of a stochastic discrete dynamical system that models a social network of 25,000 individuals engaging in risk acts over a period of 15 years. The model's parameters are based on analyses of data collected in prior studies of the real-world risk networks of people who inject drugs (PWID) in New York City. Analysis of system trajectories reveals the structural mechanisms by which individuals with mature HIV infections tend to partition the network into homogeneous clusters (with respect to infection status) and how uninfected clusters remain relatively stable (with respect to infection status) over long stretches of time. We confirm the spontaneous emergence of network firewalls in the system and reveal their structural role in the nonspreading of HIV.

Topological and Historical Considerations for Infectious Disease Transmission among Injecting Drug Users in Bushwick, Brooklyn (USA)

Recent interest by physicists in social networks and disease transmission factors has prompted debate over the topology of degree distributions in sexual networks. Social network researchers have been critical of "scale-free" Barabasi-Albert approaches, and largely rejected the preferential attachment, "rich-get-richer" assumptions that underlie that model. Instead, research on sexual networks has pointed to the importance of homophily and local sexual norms in dictating degree distributions, and thus disease transmission thresholds. Injecting Drug User (IDU) network topologies may differ from the emerging models of sexual networks, however. Degree distribution analysis of a Brooklyn, NY, IDU network indicates a different topology than the spanning tree configurations discussed for sexual networks, instead featuring comparatively short cycles and high concurrency. Our findings suggest that IDU networks do in some ways conform to a "scale-free" topology, and thus may represent "reservoirs" of potential infection despite seemingly low transmission thresholds.