Evaluating recruitment among female sex workers and injecting drug users at risk for HIV using respondent-driven sampling in Estonia

Cocaine/crack and cannabis use among transgender women in Goiás, Central Brazil

INTRODUCTION

Illicit drug use is a significant public health problem. Studies have shown a high prevalence of cocaine and cannabis use in transgender women (TGW).

OBJECTIVE

To describe the consumption patterns of cannabis and cocaine/crack use and variables associated with their use in TGW in Central Brazil.

METHODS

A cross-sectional study was conducted on TGW in Goiás, Brazil. Participants were recruited using a respondent-driven sampling method and were interviewed face-to-face about cannabis and crack-cocaine and the variables associated with them. The Alcohol Smoking and Substance Involvement Screening Test was used to assess substance use. Unweighted logistic regression was used to identify variables associated with cannabis and crack cocaine use. P-values < 0.05 were considered statistically significant.

RESULTS

A total of 440 transgender women participated in the study. Their median age was 25 years (interquartile range: 20.5-29.5 years). Most participants were single (85.5%) and had engaged in sex work in their lifetime (58.6%). Cannabis was reported by 68.9% and 53.4% of participants in their lifetime and in the past three months, respectively, and cocaine/crack use was reported by 59.8% and 44.1% of participants in their lifetime and the past three months, respectively. Of the participants, 10.2% reported high-risk cannabis use, and 9.1% reported high-risk cocaine/crack use. Furthermore, 35% of participants reported using both drugs. Previous physical violence (Adjusted Odds Ratio (AOR): 2.37), inconsistent condom uses during anal sex (AOR: 2.17), and moderate-/high-risk cocaine/crack use (AOR: 3.14) were associated with high-risk cannabis use. Previous sexual violence (AOR: 2.84), previous STI (AOR: 2.90), moderate-/high-risk cannabis (AOR: 3.82), and binge drinking (AOR; 3.28) were associated with high-risk cocaine/crack use.

CONCLUSION

Our study found a high frequency, significant overlap in the use of cannabis and cocaine/crack use and violence associated with these drugs consumption among TGW, highlighting the urgent need for health policies for drug disorders among this socially marginalized group.

Using geographical data and rolling statistics for diagnostics of respondent-driven sampling

Respondent-driven sampling (RDS) is commonly used to sample from key populations without a sampling frame since traditional methods are unable to efficiently survey them. Surveying these populations is often desirable to inform service delivery, assess effectiveness of programs, and determine prevalence of diseases. However, there are concerns about how RDS works in practice due to its many assumptions. To assess some of these assumptions, we develop diagnostics using geographical data and demonstrate their utility by identifying lack of convergence and characterizing RDS reach in surveys conducted among female sex workers and men who have sex with men in Kampala, Uganda.

Risk perception and vulnerabilities for HIV/AIDS among transgender women in Brazil: mixed methods approach

Transgender women (TW) are a key population in the dynamics of human immunodeficiency virus (HIV) dissemination, although little is known about their perceptions of HIV risk. In this embedded, nested, mixed-methods study, we assessed factors associated with condomless sexual intercourse among TW and explored their risk perceptions and vulnerabilities regarding HIV exposure. The first phase involved a cross-sectional study, followed by qualitative interviews. Condomless sexual intercourse during their last sexual encounter was reported by 37.3% of participants, and 16.1% previously tested positive for HIV. Age older than 21 years, single status, and being a sex worker were protective factors for condomless intercourse. Otherwise, TW who reported a past sexual partner with a known sexually transmitted infection and those aware of post-exposure prophylaxis had a greater risk of condomless sexual intercourse (p < 0.05) during their most recent encounter. The qualitative interviews revealed that, despite TW being aware of their risk of contracting HIV, their vulnerabilities overlapped their risk perception, making them trivialize or ignore the risk. This study will help to understand the HIV dynamics among TW and contribute to further health research, education, policymaking, and planning associated with specific health strategies to promote the sexual health of TW.

Working with economically vulnerable women engaged in sex work: Collaborating with community stakeholders in Southern Uganda

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT03583541.

Peer Recruitment Strategies for Female Sex Workers Not Engaged in HIV Prevention and Treatment Services in Côte d'Ivoire: Program Data Analysis

Background

In the context of the mostly generalized HIV epidemic in Côte d’Ivoire, key populations bear a higher burden of HIV than that borne by the general reproductive-aged population. Mathematical models have demonstrated the significant potential impact and cost-effectiveness of improving the coverage of HIV prevention and treatment services for key populations in Côte d’Ivoire. However, in 2019, coverage of these services remained limited by multiple intersecting stigmas affecting key populations, necessitating the study of innovative implementation strategies to better meet the needs of those most marginalized. Here, we leverage programmatic data to compare the effectiveness of the enhanced and traditional peer outreach approaches in reaching and providing community HIV testing to female sex workers not readily engaged in HIV prevention and treatment services in Côte d’Ivoire.

Objective

The aim of this study was to describe the characteristics of female sex workers reached by the LINKAGES project in Côte d’Ivoire with enhanced peer outreach and traditional peer outreach and to compare HIV-related outcomes between the women reached by both strategies.

Methods

Deidentified routine programmatic data collected as part of LINKAGES Côte d’Ivoire between October 2017 and April 2018 were used in these analyses. Demographic characteristics and HIV indicators including HIV testing history, HIV case-finding, linkage to HIV treatment, and treatment initiation were assessed using descriptive statistics. Differences in these indicators were compared by outreach strategy using Pearson chi-square tests.

Results

There were 9761 women reached with enhanced peer outreach and routine peer outreach included in these analyses. The overall case-finding rate in the sample was 7.8% (698/8851). Compared with women reached by routine outreach, those reached by enhanced peer outreach were more likely to have previously been tested for HIV (enhanced: 1695/2509, 67.6%; routine: 4302/7252, 60.0%; χ²₁=43.8; P=.001). The enhanced peer outreach approach was associated with a higher HIV case-finding rate (enhanced: 269/2507 10.7%; routine: 429/6344, 6.8%; χ²₁=32.3; P=.001), higher proportion of linkage to treatment (enhanced: 258/269, 95.9%; routine: 306/429, 71.3%; χ²₁=64.4; P=.001), and higher proportion of treatment initiation (enhanced: 212/269, 78.8%; routine: 315/429, 73.3%; χ²₁=2.6; P=.11). Women reached by both approaches were categorized as high risk for HIV-related behaviors such as condomless sex and number of sex acts in the previous week.

Conclusions

These analyses suggest that the novel peer-referral strategy, the enhanced peer outreach approach, was effective in reaching female sex workeres in Côte d’Ivoire with demonstrated acquisition risks for HIV and who had not been effectively engaged by routine outreach approaches. Scaling up novel strategies such as enhanced peer outreach in the context of differentiated service models may be needed to optimize HIV prevention and treatment outcomes for key populations in Côte d’Ivoire.

Prevalence of HCV among people who inject drugs in Brussels-a respondent-driven sampling survey

Background

In Belgium, people who inject drugs (PWID) are at a high risk of being infected by hepatitis C (HCV) as injecting drug use is the main mode for transmission of HCV in Europe. Estimates about the number of people living with HCV in Belgium are rare and even less is known about the prevalence of HCV among PWID.

Method

Between 1 February 2019 and 26 April 2019, PWID and high-risk opiate users (HROU) were recruited in Brussels through respondent-driven sampling (RDS). They were invited to a questionnaire and underwent a rapid HCV test.

Results

A total of 253 respondents participated in the study, of which 168 were PWID and 238 were HROU, with 153 respondents belonging to both categories. The overall unweighted sample average for HCV antibodies was 41.1%. The weighted population estimates were 43.7% (95% CI 30.6–56.8%) for RDS-II and 43.4% (95% CI 28.9–58.0%) for RDS-SS.

Conclusions

This prevalence is lower than the prevalence estimates reported elsewhere in Europe. However, the data still suggest that serious efforts are needed to reach the goal set by the WHO to reduce HCV by 2030 with 90%.

Implementing Respondent-Driven Sampling to Recruit Women Who Exchange Sex in New York City: Factors Associated with Recruitment and Lessons Learned

Respondent-driven sampling (RDS) relies on productive peer recruitment to capture hidden populations. Domestic studies have identified characteristics of productive recruitment among RDS samples of men who have sex with men and persons who use drugs, but not of women who exchange sex, a group vulnerable to HIV infection. We examined sociodemographic-, behavioral-, exchange-sex-, and protocol-related factors associated with recruitment among seeds (n = 25) and peers (n = 297) in the 2016 New York City National HIV Behavioral Surveillance Study cycle focused on women who exchange sex. Recruiter productivity was significantly associated with not having been recently incarcerated, lower rate of HIV testing, and larger exchange sex networks among seeds, and with HIV-prevention services usage among peers. We describe challenges and lessons learned from implementing RDS in this population. Our study identifies seed characteristics and protocol improvements researchers can utilize when implementing future RDS studies among women who exchange sex.

Using Social Networks to Understand and Overcome Implementation Barriers in the Global HIV Response

BACKGROUND

Despite the development of several efficacious HIV prevention and treatment methods in the past 2 decades, HIV continues to spread globally. Uptake of interventions is nonrandomly distributed across populations. Such inequality is socially patterned and reinforced by homophily arising from both social selection (becoming friends with similar people) and influence (becoming similar to friends).

METHODS

We conducted a narrative review to describe how social network analysis methods-including egocentric, sociocentric, and respondent-driven sampling designs-provide tools to measure key populations, to understand how epidemics spread, and to evaluate intervention take-up.

RESULTS

Social network analysis-informed designs can improve intervention effectiveness by reaching otherwise inaccessible populations. They can also improve intervention efficiency by maximizing spillovers, through social ties, to at-risk but susceptible individuals. Social network analysis-informed designs thus have the potential to be both more effective and less unequal in their effects, compared with social network analysis-naïve approaches. Although social network analysis-informed designs are often resource-intensive, we believe they provide unique insights that can help reach those most in need of HIV prevention and treatment interventions.

CONCLUSION

Increased collection of social network data during both research and implementation work would provide important information to improve the roll-out of existing studies in the present and to inform the design of more data-efficient, social network analysis-informed interventions in the future. Doing so will improve the reach of interventions, especially to key populations, and to maximize intervention impact once delivered.

Reaching the unreached: Performance of an enhanced peer outreach approach to identify new HIV cases among female sex workers and men who have sex with men in HIV programs in West and Central Africa

Finding new HIV-positive cases remains a priority to achieve the UNAIDS goals. An enhanced peer outreach approach (EPOA) was implemented to expand the delivery of HIV services to female sex workers (FSWs) and men who have sex with men (MSM) in three countries in West and Central Africa. The aim of EPOA is to identify new HIV-positive cases. EPOA was implemented in Burundi among FSWs, and in Cote d'Ivoire and Democratic Republic of the Congo (DRC) among both FSWs and MSM. Implementation ranged from five to nine weeks and was nested within a three-month reporting period. Standard outreach was suspended for the duration of EPOA implementation but was resumed thereafter. Summary service statistics were used to compare HIV seropositivity during standard outreach and EPOA. Trends were analyzed during the quarter in which EPOA was implemented, and these were compared with the two preceding quarters. Differences in proportions of HIV seropositivity were tested using Pearson's chi-square test; p-values of less than 0.05 were considered statistically significant. Overall, EPOA resulted in a higher proportion of new HIV-positive cases being found, both within and between quarters. In Burundi, HIV seropositivity among FSWs was significantly higher during EPOA than during standard outreach (10.8% vs. 4.1%, p<0.001). In Cote d'Ivoire, HIV seropositivity was significantly higher during EPOA among both populations (FSWs: 5.6% vs. 1.81%, p<0.01; MSM: 15.4% vs. 5.9%; p<0.01). In DRC, HIV seropositivity was significantly higher during EPOA among MSM (6.9% vs. 1.6%; p<0.001), but not among FSWs (5.2% vs. 4.3%; p = 0.08). Trends in HIV seropositivity during routine outreach for both populations were constant during three successive quarters but increased with the introduction of EPOA. EPOA is a public health approach with great potential for reaching new populations and ensuring that they are aware of their HIV status.

Empirical evidence of recruitment bias in a network study of people who inject drugs

Background: Epidemiologic surveys of people who inject drugs (PWID) can be difficult to conduct because potential participants may fear exposure or legal repercussions. Respondent-driven sampling (RDS) is a procedure in which subjects recruit their eligible social contacts. The statistical validity of RDS surveys of PWID and other risk groups depends on subjects recruiting at random from among their network contacts. Objectives: We sought to develop and apply a rigorous definition and statistical tests for uniform network recruitment in an RDS survey. Methods: We undertook a detailed study of recruitment bias in a unique RDS study of PWID in Hartford, CT, the USA in which the network, individual-level covariates, and social link attributes were recorded. A total of n=527 participants (402 male, 123 female, and two individuals who did not specify their gender) within a network of 2626 PWID were recruited. Results: We found strong evidence of recruitment bias with respect to age, homelessness, and social relationship characteristics. In the discrete model, the estimated hazard ratios regarding the significant features of recruitment time and choice of recruitee were: alter's age 1.03 [1.02, 1.05], alter's crack-using status 0.70 [0.50, 1.00], homelessness difference 0.61 [0.43, 0.87], and sharing activities in drug preparation 2.82 [1.39, 5.72]. Under both the discrete and continuous-time recruitment regression models, we reject the null hypothesis of uniform recruitment. Conclusions: The results provide the evidence that for this study population of PWID, recruitment bias may significantly alter the sample composition, making results of RDS surveys less reliable. More broadly, RDS studies that fail to collect comprehensive network data may not be able to detect biased recruitment when it occurs.

Estimating the Population Size of Female Sex Workers in Three South African Cities: Results and Recommendations From the 2013-2014 South Africa Health Monitoring Survey and Stakeholder Consensus

Background

Robust population size estimates of female sex workers and other key populations in South Africa face multiple methodological limitations, including inconsistencies in surveillance and programmatic indicators. This has, consequently, challenged the appropriate allocation of resources and benchmark-setting necessary to an effective HIV response. A 2013-2014 integrated biological and behavioral surveillance (IBBS) survey from South Africa showed alarmingly high HIV prevalence among female sex workers in South Africa’s three largest cities of Johannesburg (71.8%), Cape Town (39.7%), and eThekwini (53.5%). The survey also included several multiplier-based population size estimation methods.

Objective

The objective of our study was to present the selected population size estimation methods used in an IBBS survey and the subsequent participatory process used to estimate the number of female sex workers in three South African cities.

Methods

In 2013-2014, we used respondent-driven sampling to recruit independent samples of female sex workers for IBBS surveys in Johannesburg, Cape Town, and eThekwini. We embedded multiple multiplier-based population size estimation methods into the survey, from which investigators calculated weighted estimates and ranges of population size estimates for each city’s female sex worker population. Following data analysis, investigators consulted civil society stakeholders to present survey results and size estimates and facilitated stakeholder vetting of individual estimates to arrive at consensus point estimates with upper and lower plausibility bounds.

Results

In total, 764, 650, and 766 female sex workers participated in the survey in Johannesburg, Cape Town, and eThekwini, respectively. For size estimation, investigators calculated preliminary point estimates as the median of the multiple estimation methods embedded in the IBBS survey and presented these to a civil society-convened stakeholder group. Stakeholders vetted all estimates in light of other data points, including programmatic experience, ensuring inclusion only of plausible point estimates in median calculation. After vetting, stakeholders adopted three consensus point estimates with plausible ranges: Johannesburg 7697 (5000-10,895); Cape Town 6500 (4579-9000); eThekwini 9323 (4000-10,000).

Conclusions

Using several population size estimates methods embedded in an IBBS survey and a participatory stakeholder consensus process, the South Africa Health Monitoring Survey produced female sex worker size estimates representing approximately 0.48%, 0.49%, and 0.77% of the adult female population in Johannesburg, Cape Town, and eThekwini, respectively. In data-sparse environments, stakeholder engagement and consensus is critical to vetting of multiple empirically based size estimates procedures to ensure adoption and utilization of data-informed size estimates for coordinated national and subnational benchmarking. It also has the potential to increase coherence in national and key population-specific HIV responses and to decrease the likelihood of duplicative and wasteful resource allocation. We recommend building cooperative and productive academic-civil society partnerships around estimates and other strategic information dissemination and sharing to facilitate the incorporation of additional data as it becomes available, as these additional data points may minimize the impact of the known and unknown biases inherent in any single, investigator-calculated method.

Overlooked Threats to Respondent Driven Sampling Estimators: Peer Recruitment Reality, Degree Measures, and Random Selection Assumption

Intensive sociometric network data were collected from a typical respondent driven sample (RDS) of 528 people who inject drugs residing in Hartford, Connecticut in 2012-2013. This rich dataset enabled us to analyze a large number of unobserved network nodes and ties for the purpose of assessing common assumptions underlying RDS estimators. Results show that several assumptions central to RDS estimators, such as random selection, enrollment probability proportional to degree, and recruitment occurring over recruiter's network ties, were violated. These problems stem from an overly simplistic conceptualization of peer recruitment processes and dynamics. We found nearly half of participants were recruited via coupon redistribution on the street. Non-uniform patterns occurred in multiple recruitment stages related to both recruiter behavior (choosing and reaching alters, passing coupons, etc.) and recruit behavior (accepting/rejecting coupons, failing to enter study, passing coupons to others). Some factors associated with these patterns were also associated with HIV risk.

Identification of Homophily and Preferential Recruitment in Respondent-Driven Sampling

Respondent-driven sampling (RDS) is a link-tracing procedure used in epidemiologic research on hidden or hard-to-reach populations in which subjects recruit others via their social networks. Estimates from RDS studies may have poor statistical properties due to statistical dependence in sampled subjects' traits. Two distinct mechanisms account for dependence in an RDS study: homophily, the tendency for individuals to share social ties with others exhibiting similar characteristics, and preferential recruitment, in which recruiters do not recruit uniformly at random from their network alters. The different effects of network homophily and preferential recruitment in RDS studies have been a source of confusion and controversy in methodological and empirical research in epidemiology. In this work, we gave formal definitions of homophily and preferential recruitment and showed that neither is identified in typical RDS studies. We derived nonparametric identification regions for homophily and preferential recruitment and showed that these parameters were not identified unless the network took a degenerate form. The results indicated that claims of homophily or recruitment bias measured from empirical RDS studies may not be credible. We applied our identification results to a study involving both a network census and RDS on a population of injection drug users in Hartford, Connecticut (2012-2013).

Internet recruitment for sexually transmitted infection screening among men who have sex with men in Eastern Europe

Men who have sex with men (MSM) face negative health outcomes such as sexually transmitted infections (STIs) at disproportionate rates. Nonetheless, infections may be underestimated due to limited uptake in testing. To increase testing, screening interventions have been utilized in the past; however, some have resulted in limitations such as poor recruitment. To increase recruitment for screening of MSM in Estonia, two different recruitment strategies were examined. Recruitment was separated into two promotional periods: passive and active. Passive consisted of banners on gay-related sites, while active also placed banners on websites to the general public such as Facebook linked to specific thematic pages and users self-identifying as men. More men were recruited during the active period of five weeks (n = 134) than the passive period of 46 weeks (n = 126). Active promotion was so successful in that the number of home sampling kit orders far exceeded what was projected, forcing promotion to the general public to be closed after 13 days. Recruiting MSM through a combination of general public and gay-related websites and applications has the ability to quickly recruit for testing interventions. This method can recruit a large number in a short amount of time; therefore, a budget must be planned accordingly to support testing for all that participate.

Engagement in HIV care and its correlates among people who inject drugs in St Petersburg, Russian Federation and Kohtla-Järve, Estonia

BACKGROUND AND AIMS

HIV infection and mortality in Eastern Europe are driven by unsafe injection drug use. We sought to compare engagement in care from HIV testing through receipt of antiretroviral treatment among HIV-positive people who inject drugs (PWID) in St Petersburg, Russian Federation (RF) and Kohtla-Järve, Estonia and identify factors associated significantly with failure to progress at each stage of the HIV treatment cascade.

DESIGN

Cross-sectional biobehavioral surveys of PWID with an analysis stratified by location-two Russian-speaking regions with similar HIV epidemic histories and current prevalence.

SETTING

Field-based surveys conducted in St Petersburg, RF and Kohtla-Järve, Estonia.

PARTICIPANTS

We recruited 452 HIV-positive PWID in St Petersburg (November 2012 to June 2013) and 370 HIV-positive PWID in Kohtla-Järve (June-August 2012) using respondent-driven sampling.

MEASUREMENTS

Participants were tested for antibodies to HIV, and administered a questionnaire focusing on participants' medical care histories. Engagement in care was categorized as a cascade of five transitional steps through six stages, ranging from HIV testing to current receipt of antiretroviral medications.

FINDINGS

Progress along the cascade was greater in Kohtla Järve (32.7% were receiving antiretroviral medications) than in St Petersburg (9.7%). In both locations, we found the steps with high failure rates were the transitions from being aware of one's HIV diagnosis to being in regular care and initiation of highly active antiretroviral therapy (HAART). Factors associated significantly with transition failure in both locations and across steps included high alcohol consumption, variables associated with drug choice and injection frequency and lack of basic medical insurance.

CONCLUSION

The two steps in treatment cascade for HIV-positive PWID in St Petersburg, RF and Kohtla-Järve, Estonia requiring greatest improvement are retention in regular care and initiation of HAART. Both individual behavioral and structural factors are associated with failure to transition along the cascade.

HIV prevalence and gender differences among new injection-drug-users in Tallinn, Estonia: A persisting problem in a stable high prevalence epidemic

INTRODUCTION

New injectors / younger drug users are an important population to target for intervention because they are often at especially high risk of HIV and HCV infection. We examined HIV prevalence and gender differences in HIV prevalence and risk behavior among new injection-drug-users in Tallinn, Estonia.

METHODS

Respondent driven sampling (RDS) interview surveys and HIV testing were conducted in Tallinn in 2009, 2011 and 2013. We classified "new injectors" as persons who reported their first injection as occurring within three years of the study interview. Recruiting trees of the three individual RDS studies were joined to form one RDS dataset and RDS estimates for prevalence and means were derived. Bootstrap tests were used to compare data from men and women, HIV infected and uninfected.

RESULTS

Among 110 new injectors (34 women and 76 men) the mean age was 24.5 (SD 7.5) years; 63% reported injecting mainly fentanyl, 34% injecting mainly amphetamine, 36% sharing syringes, 89% were sexually active, and, of these, 88% did not always use condoms in the last 6 months. HIV prevalence was 18% (95%CI 8-28%) (41% (95%CI 19-63%) among female and 7% (95%CI 2-12%) among male new injectors). Based on self-reports, 8.1% of all new injectors (and 22% of female new injectors) were HIV positive before starting to inject drugs. 40% of HIV infected reported receiving antiretroviral therapy. In multivariable analysis, gender (male: OR 0.12, 95% CI 0.03-0.45), main drug injected (fentanyl: OR 6.7, 95% CI 1.3-35.7) and syringe sharing (distributive: OR 0.11, 95% CI 0.02-0.55; and receptive: OR 3.7, 95% CI 1.0-13.5) were associated with the HIV seropositivity.

CONCLUSIONS

New injectors exhibit high-risk behavior and correspondingly high HIV prevalence. Sexual transmission of HIV infection, including before injection initiation, is likely to be a significant contributor to HIV risk among female new injectors. This highlights the need to identify and target new injectors and their partners with gender specific interventions in addition to interventions to reduce initiation into injecting and ensuring provision of ART to HIV positive new injectors.

Barriers to Viral Suppression Among Female Sex Workers: Role of Structural and Intimate Partner Dynamics

OBJECTIVE

Despite global evidence that sex workers (SWs) are disproportionately impacted by HIV, data on HIV treatment outcomes among SWs living with HIV remains sparse. This study examined the correlates of undetectable plasma viral load (pVL) among street- and off-street SWs living with HIV and on antiretroviral therapy (ART) in Metro Vancouver, Canada.

METHODS

Analyses drew on data (2010-2014) from a longitudinal cohort of SWs (An Evaluation of Sex Workers Health Access) and confidential linkages with the Drug Treatment Program (DTP) data on ART dispensation and outcomes. Bivariate and multivariable generalized linear mixed-effects models were used to identify longitudinal correlates of undetectable pVL (<50 copies/mL).

RESULTS

Of the 72 SWs living with HIV who had ever used ART, 38.9% had an undetectable pVL at baseline. Although 84.7% had undetectable pVL at least once over the study period, 18.1% exhibited sustained undetectable pVL. In multivariable generalized linear mixed-effects model analyses, ≥95% pharmacy refill adherence (adjusted odds ratio (AOR) = 4.21; 95% confidence interval (CI) 2.16 to 8.19) and length of time since diagnosis (AOR = 1.06; 95% CI: 1.00 to 1.13) were positively correlated with undetectable pVL. Having an intimate male partner (AOR = 0.35; 95% CI: 0.16 to 0.78) and being homelessness were negatively correlated with undetectable pVL (AOR = 0.22; 95% CI: 0.10 to 0.47).

DISCUSSION/CONCLUSIONS

There is a need to more closely consider the social and structural contexts that shape SWs' experiences on ART and impact treatment outcomes, including the gendered power dynamics within intimate partnerships. Future research on HIV care among SWs is urgently needed, alongside structural and community-led interventions to support SWs' access to and retention in care.

A Systematic Review of Published Respondent-Driven Sampling Surveys Collecting Behavioral and Biologic Data

Reporting key details of respondent-driven sampling (RDS) survey implementation and analysis is essential for assessing the quality of RDS surveys. RDS is both a recruitment and analytic method and, as such, it is important to adequately describe both aspects in publications. We extracted data from peer-reviewed literature published through September, 2013 that reported collected biological specimens using RDS. We identified 151 eligible peer-reviewed articles describing 222 surveys conducted in seven regions throughout the world. Most published surveys reported basic implementation information such as survey city, country, year, population sampled, interview method, and final sample size. However, many surveys did not report essential methodological and analytical information for assessing RDS survey quality, including number of recruitment sites, seeds at start and end, maximum number of waves, and whether data were adjusted for network size. Understanding the quality of data collection and analysis in RDS is useful for effectively planning public health service delivery and funding priorities.

Hard-to-reach populations of men who have sex with men and sex workers: a systematic review on sampling methods

BACKGROUND

In public health, hard-to-reach populations are often recruited by non-probabilistic sampling methods that produce biased results. In order to overcome this, several sampling methods have been improved and developed in the last years. The aim of this systematic review was to identify all current methods used to survey most-at-risk populations of men who have sex with men and sex workers. The review also aimed to assess if there were any relations between the study populations and the sampling methods used to recruit them. Lastly, we wanted to assess if the number of publications originated in middle and low human development (MLHD) countries had been increasing in the last years.

METHODS

A systematic review was conducted using electronic databases and a total of 268 published studies were included in the analysis.

RESULTS

In this review, 11 recruitment methods were identified. Semi-probabilistic methods were used most commonly to survey men who have sex with men, and the use of the Internet was the method that gathered more respondents. We found that female sex workers were more frequently recruited through non-probabilistic methods than men who have sex with men (odds = 2.2; p < 0.05; confidence interval (CI) [1.1-4.2]). In the last 6 years, the number of studies based in middle and low human development countries increased more than the number of studies based in very high and high human development countries (odds = 2.5; p < 0.05; CI [1.3-4.9]).

CONCLUSIONS

This systematic literature review identified 11 methods used to sample men who have sex with men and female sex workers. There is an association between the type of sampling method and the population being studied. The number of studies based in middle and low human development countries has increased in the last 6 years of this study.

Competition is not necessarily a barrier to community mobilisation among sex workers: an intervention planning assessment from Zimbabwe

BACKGROUND

Community mobilization among female sex workers (SWs) is recognized as an effective strategy to empower SWs and increase their uptake of health services. Activities focus on increasing social cohesion between SWs by building trust, strengthening networks, and encouraging shared efforts for mutual gain. Several studies, however, suggest that high levels of interpersonal competition between SWs can pose a barrier to collective action and support. We conducted a study to examine levels of perceived competition between SWs in Mutare, Hwange and Victoria Falls in Zimbabwe in order to inform development of a community-based intervention for HIV prevention and treatment. This paper focuses on our qualitative findings and their implications for the design of HIV programming in the Zimbabwean context.

METHODS

Following a respondent driven sampling (RDS) survey, we explored issues related to social cohesion amongst SWs in Mutare, Hwange and Victoria Falls through in-depth interviews conducted with 22 SWs. Interviews examined dynamics of SWs' relationships and extent of social support, and were analyzed using thematic content analysis using the constant comparative method. Findings are contextualised against descriptive data extracted from the survey, which was analysed using Stata 12, adjusting for RDS.

RESULTS

Across all sites, women described protecting each other at night, advising each other about violent or non-paying clients, and paying fines for each other following arrest. In Mutare, women gave additional examples, including physically attacking problem clients, treatment adherence support and shared saving schemes. However, interviews also highlighted fierce competition between women and deep mistrust. This reflects the reported mix of competition and support from the survey of 836 women (Mutare n = 370, Hwange n = 237, Victoria Falls n = 229). In Mutare, 92.8 % of SWs agreed there was a lot of competition; 87.9 % reported that SWs support each other. This contrasted with Victoria Falls and Hwange where fewer agreed there was competition between SWs (70.5 % and 78.0 %), but also fewer reported that SWs support each other at work (55.2 % and 51.2 %).

CONCLUSIONS

Women reported being most likely to support each other when confronted with serious danger but maintained high levels of competition for clients, suggesting competition at work does not represent a barrier to support. Examples of practical assistance between SWs provide entry points for our planned community mobilization activities, which aim to broaden trust and support among SWs while acknowledging their professional competition.

Vulnerability to sexually transmitted infections in women who sell sex on the route of prostitution and sex tourism in central Brazil

OBJECTIVE

to investigate knowledge on sexually transmitted diseases (STDs), STD-related risk behaviors, and signs/symptoms of STDs among female sex workers (FSWs).

METHODS

a cross-sectional study was conducted with a probabilistic sample comprising 395 women recruited using a respondent-driven sampling method between 2009 and 2010. The data were collected during face-to-face interviews.

RESULTS

most of the participants were young adults, had a low educational level, and had poor knowledge on the transmission paths of the human immunodeficiency virus (HIV). Over one-third of the participants were not able to describe the signs/symptoms of STDs. The prevalence rates of vaginal discharge and wounds/ulcers were 49.0% and 8.6%, respectively, but 41.7% of the women had not sought treatment.

CONCLUSION

the results indicate the need for public health policies focusing on the control and prevention of STDs in this population, especially for the FSWs who are active in an important prostitution and sex tourism route in central Brazil.

Social and structural constraints on disclosure and informed consent for HIV survey research involving female sex workers and their bar managers in the Philippines

This qualitative study explored the ethical issues of female sex workers' (FSWs) participation in HIV prevention research. Twenty female bar/spa workers and 10 venue managers in the Philippines underwent individual semi-structured interviews; three community advisory board meetings informed the study design and interpretation of findings.

RESULTS

Informed consent was constrained by perceived government coercion and skepticism that research results would translate into community benefits. Disclosure was constrained by distrust in confidentiality and perceived intrusiveness of survey questions. FSWs and managers were frustrated by the government's inability to stop police from using condoms as evidence of prostitution. Findings suggest HIV interventions move beyond didactic prevention workshops to include FSWs in intervention design and implementation, and to reduce social and structural constraints on participation.

HIV/STI risk among venue-based female sex workers across the globe: a look back and the way forward

Female sex workers (FSWs) continue to represent a high-risk population in need of targeted HIV prevention interventions. Targeting environmental risk factors should result in more sustainable behavior change than individual-level interventions alone. There are many types of FSWs who operate in and through a variety of micro- (eg, brothels) and macro-level (eg, being sex-trafficked) contexts. Efforts to characterize FSWs and inform HIV prevention programs have often relied on sex work typologies or categorizations of FSWs by venue or type. We conducted a systematic search and qualitatively reviewed 37 published studies on venue-based FSWs to examine the appropriateness of sex work typologies, and the extent to which this research has systematically examined characteristics of different risk environments. We extracted information on study characteristics like venue comparisons, HIV/STI prevalence, and sampling strategies. We found mixed results with regards to the reliability of typologies in predicting HIV/STI infection; relying solely on categorization of FSWs by venue or type did not predict seroprevalence in a consistent manner. Only 65 % of the studies that allowed for venue comparisons on HIV/STI prevalence provided data on venue characteristics. The factors that were assessed were largely individual-level FSW factors (eg, demographics, number of clients per day), rather than social and structural characteristics of the risk environment. We outline a strategy for future research on venue-based FSWs that ultimately aims to inform structural-level HIV interventions for FSWs.

Beyond surveillance: a role for respondent-driven sampling in implementation science

We are now in the fourth decade of the human immunodeficiency virus (HIV) pandemic. Several novel prevention tools have been identified, and prevalence and incidence have declined in many settings. A remaining challenge is the delivery of preventive interventions to hard-to-reach populations, including men who have sex with men and injection drug users. Leaders in the field of HIV have called for a new focus on implementation science, which requires a shift in thinking from individual randomized controlled trials to cluster-randomized trials. Multiple challenges need to be addressed in the conduct of cluster-randomized trials, including: 1) generalizability of the study population to the target population, 2) potential contamination through overlap/exchange of members of control and intervention clusters, and 3) evaluation of effectiveness at multiple levels of influence. To address these key challenges, we propose a novel application of respondent-driven sampling-a chain-referral strategy commonly used for surveillance-in the recruitment of participants for the evaluation of a cluster-randomized trial of a community intervention. We illustrate this application with an empirical example of a cluster-randomized trial that is currently under way to assess the effectiveness of men's wellness centers in improving utilization of HIV counseling and testing among men who have sex with men in India.

Filling the Knowledge Gap: Measuring HIV Prevalence and Risk Factors among Men Who Have Sex with Men and Female Sex Workers in Tripoli, Libya

Background

Publications on Libya’s HIV epidemic mostly examined the victims of the tragic nosocomial HIV outbreak in the 1990s and the related dispute about the detention of foreign medical workers. The dispute resolution in 2003 included an agreement with the European Union on humanitarian cooperation and the development of Libya’s first National HIV Strategy. As part of this we conducted Libya’s first bio-behavioural survey among men having sex with men (MSM) and female sex workers (FSW).

Methods

Using respondent-driven sampling, we conducted a cross-sectional study to estimate the prevalence of HIV, hepatitis B virus (HBV), hepatitis C virus (HCV), and related risk factors among 227 MSM and 69 FSW in Tripoli (FSW recruitment ended prematurely due to the political events in 2011).

Results

For MSM we estimated an HIV prevalence of 3.1%, HBV prevalence of 2.9%, and HCV prevalence of 7.3%, and for FSW an HIV prevalence of 15.7%, HBV prevalence of 0%, and HCV prevalence of 5.2%. We detected high levels of risk behaviours, poor HIV-related knowledge, high stigma and lack of prevention programmes. These results must be interpreted in the context of the political situation which prohibited reaching an ideal sample size for FSW.

Conclusion

There is urgent need to implement an effective National HIV Strategy informed by the results of this research. The risk of transmission within different risk groups and to the general population may be high given the recent military events that led to increased violence, migration, and the disruption of essential HIV-related services.

Effectiveness of respondent driven sampling to recruit undocumented Central American immigrant women in Houston, Texas for an HIV behavioral survey

Respondent driven sampling (RDS) is widely used for HIV behavioral research among sex workers, drug users, and other hidden populations, but has had limited application in immigrant populations in the U.S. In 2010, we used RDS to recruit undocumented Central American immigrant women in Houston, Texas for an HIV behavioral survey. Beginning with three initial participants we recruited 226 women within 16 weeks. Social networks were dense and participants adopted the recruitment system with reasonable ease. Homophily scores indicated moderate within-group preference by country of origin. However, cross-group recruitment was sufficient to achieve a diverse sample that attained equilibrium for all demographic and sexual behavior characteristics. Overall, RDS was easy to implement, attained a large sample in a relatively short period of time, and reached an otherwise hidden population. Our results suggest that RDS is an effective method for recruiting undocumented Latina immigrants for HIV behavioral surveys.

Global epidemiology of HIV infection in men who have sex with men

Epidemics of HIV in men who have sex with men (MSM) continue to expand in most countries. We sought to understand the epidemiological drivers of the global epidemic in MSM and why it continues unabated. We did a comprehensive review of available data for HIV prevalence, incidence, risk factors, and the molecular epidemiology of HIV in MSM from 2007 to 2011, and modelled the dynamics of HIV transmission with an agent-based simulation. Our findings show that the high probability of transmission per act through receptive anal intercourse has a central role in explaining the disproportionate disease burden in MSM. HIV can be transmitted through large MSM networks at great speed. Molecular epidemiological data show substantial clustering of HIV infections in MSM networks, and higher rates of dual-variant and multiple-variant HIV infection in MSM than in heterosexual people in the same populations. Prevention strategies that lower biological transmission and acquisition risks, such as approaches based on antiretrovirals, offer promise for controlling the expanding epidemic in MSM, but their potential effectiveness is limited by structural factors that contribute to low health-seeking behaviours in populations of MSM in many parts of the world.

Hepatitis C prevalence in injecting drug users in Europe, 1990-2007: impact of study recruitment setting

Monitoring injecting drug users' (IDUs) health is challenging because IDUs form a difficult to reach population. We examined the impact of recruitment setting on hepatitis C prevalence. Individual datasets from 12 studies were merged. Predictors of HCV positivity were sought through a multilevel analysis using a mixed-effects logistic model, with study identifier as random intercept. HCV prevalence ranged from 21% to 86% across the studies. Overall, HCV prevalence was higher in IDUs recruited in drug treatment centres compared to those recruited in low-threshold settings (74% and 42%, respectively, P < 0·001). Recruitment setting remained significantly associated with HCV prevalence after adjustment for duration of injecting and recent injection (adjusted odds ratio 0·7, 95% confidence interval 0·6-0·8, P = 0·05). Recruitment setting may have an impact on HCV prevalence estimates of IDUs in Europe. Assessing the impact of mixed recruitment strategies, including respondent-driven sampling, on HCV prevalence estimates, would be valuable.

Respondent-driven sampling and the recruitment of people with small injecting networks

Respondent-driven sampling (RDS) is a form of chain-referral sampling, similar to snowball sampling, which was developed to reach hidden populations such as people who inject drugs (PWID). RDS is said to reach members of a hidden population that may not be accessible through other sampling methods. However, less attention has been paid as to whether there are segments of the population that are more likely to be missed by RDS. This study examined the ability of RDS to capture people with small injecting networks. A study of PWID, using RDS, was conducted in 2009 in Sydney, Australia. The size of participants' injecting networks was examined by recruitment chain and wave. Participants' injecting network characteristics were compared to those of participants from a separate pharmacy-based study. A logistic regression analysis was conducted to examine the characteristics independently associated with having small injecting networks, using the combined RDS and pharmacy-based samples. In comparison with the pharmacy-recruited participants, RDS participants were almost 80% less likely to have small injecting networks, after adjusting for other variables. RDS participants were also more likely to have their injecting networks form a larger proportion of those in their social networks, and to have acquaintances as part of their injecting networks. Compared to those with larger injecting networks, individuals with small injecting networks were equally likely to engage in receptive sharing of injecting equipment, but less likely to have had contact with prevention services. These findings suggest that those with small injecting networks are an important group to recruit, and that RDS is less likely to capture these individuals.

Respondent-driven sampling to recruit young adult non-medical users of pharmaceutical opioids: problems and solutions

Respondent-driven sampling (RDS) has been promoted as a superior method in recruiting hard-to-reach and hidden populations. Although its application has expanded enormously, there remains a need for empirical data evaluating the performance of RDS in different settings. This study describes the application of RDS to recruit a community sample (N=396) of young adults (18-23 years old) into a natural history study of non-medical pharmaceutical opioid use. Since recruitment targeted non-dependent pharmaceutical opioid users, and applied other eligibility restrictions, several modifications had to be made to make RDS work with this narrowly defined target population. RDS recruitment was less efficient than expected, and produced greater numbers of African American recruits than anticipated. Although the sampling quota was met, sample analysis revealed a lack of equilibrium in terms of ethnic composition and very strong in-group recruitment tendencies among White and African American respondents. This study contributes potentially helpful insights into the strengths and limitations of using RDS which may benefit future studies.

Case study: An ethics case study of HIV prevention research on Facebook: the Just/Us study

OBJECTIVE

To consider issues related to research with youth on social networking sites online.

METHODS

Description of the data collection process from 1,588 participants in a randomized controlled trial testing the efficacy of HIV prevention education delivered on Facebook. Using respondent-driven sampling, staff-recruited participants are encouraged to recruit up to three friends to enroll in the study.

RESULTS

Researchers should (a) consider whether an online social networking site is an appropriate place to implement a research study; (b) offer opportunities to review informed consent documents at multiple times and in multiple locations throughout the study; and (c) collect data outside the social networking site and store it behind secure firewalls to ensure it will not be accessible to any person on the social networking site.

CONCLUSIONS

Online social networks are growing in popularity. Conducting research on social media sites requires deliberate attention to consent, confidentiality, and security.

Conducting a respondent-driven sampling survey with the use of existing resources in Sydney, Australia

BACKGROUND

Respondent-driven sampling (RDS) is a form of chain-referral sampling that is increasingly being used for HIV behavioural surveillance. When used for surveillance purposes, a sampling method should be relatively inexpensive and simple to operate. This study examined whether an RDS survey of people who inject drugs (PWID) in Sydney, Australia, could be successfully conducted through the use of minimal and existing resources.

METHOD

The RDS survey was conducted on the premises of a local needle and syringe program (NSP) with some adjustments to take into account the constraints of existing resources. The impact of the survey on clients and on staff was examined by summarizing NSP service data and by conducting post-survey discussions with NSP staff.

RESULTS

From November 2009 till March 2010, 261 participants were recruited in 16 waves. A significant increase was found in the number of services provided by the NSP during and after data collection. Generally, staff felt that the survey had a positive impact by exposing a broader group of people to the NSP. However, conducting the survey may have led to privacy issues for NSP clients due to an increased number of people gathering around the NSP.

CONCLUSIONS

This study shows that RDS can be conducted with the use of minimal and existing resources under certain conditions (e.g., use of a self-administered questionnaire and no biological samples taken). A more detailed cost-utility analysis is needed to determine whether RDS' advantages outweigh potential challenges when compared to simpler and less costly convenience methods.

Cannabis Dependence and Peer Selection in Social Networks of Frequent Users

In a Dutch longitudinal study on the dynamics of cannabis dependence, at baseline 600 frequent cannabis users (? 3 days cannabis use per week in past 12 months) aged 18–30 years were interviewed. Nearly half of all participants (42%) met DSM-IV criteria for cannabis dependence in the 12 months prior to the interview. Participants were recruited by respondent-driven sampling; referrals were understood as proxy for social networks to explore peer associations and social exclusion. Analyses revealed that networks of frequent cannabis users were mostly heterogeneous. Cannabis dependence did not emerge as a main selector. However, within segments of networks some clustering of cannabis dependence (indicating differential inclusion), sex and ethnicity was found. Methodological questions are discussed regarding the applicability of respondent-driven sampling in noninjecting, nonmarginalized drug users. The study's limitations are noted.

Sexual risk and HIV infection among drug users in New York City: a pilot study

Measures of sexual health were assessed during 2008-2009 in a New York City sample of 102 injection and noninjection users of heroin, cocaine, or crack. There was considerable overlap and transitioning between crack smoking and injecting. Crack users were also significantly more likely to be gay, lesbian, or bisexual than other drug users. In multivariate analysis, HIV infection was independently associated with crack use and with being gay or bisexual. In New York City, HIV prevention for drug users has focused on syringe access, safe injection, and drug user treatment, but further progress in HIV control will require strategies to address sexual health among people who use drugs. The study's limitations are noted.