Assessing the assumptions of respondent-driven sampling in the national HIV Behavioral Surveillance System among injecting drug users

The Development and the Assessment of Sampling Methods for Hard-to-Reach Populations in HIV Surveillance

Due to stigma or legal issues, populations with higher HIV risk are often hard to reach, which impedes accurate population estimation of HIV burden. To better sample hard-to-reach populations (HTRPs) for HIV surveillance, various sampling methods have been designed and/or used since HIV epidemic following the first reported AIDS cases in 1981. This paper describes the development and the assessment (i.e., validity and reproducibility) of approximately eight sampling methods (e.g., convenience sampling, snowball sampling, time location sampling, and respondent-driven sampling) for HTRPs in HIV surveillance, with a focus on respondent-driven sampling (RDS). Compared to other methods, RDS has been greatly assessed. However, current evidence is still inadequate for RDS to be considered the best option for sampling HTRPs. The field must continue to assess RDS and to develop new sampling approaches or modifications to existing approaches.

Community-based respondent-driven sampling as a strategy for drug use surveillance in a large French urban area

BACKGROUND

Understanding drug use and behavior within the PWUD population is crucial to adapt harm reduction and prevention strategies, and provide improved addiction and medical treatment. However, in most countries such as France, the knowledge of drug use behaviors is likely biased as it originates from addiction centers which are attended by only an unknown proportion of PWUD. The objectives of this study were to describe drug use behavior in a population of active PWUD in the urban area of Montpellier, South of France.

METHODS

We implemented a community-based respondent-driven sampling survey (RDSS), a validated strategy to obtain a representative sample of a population, to recruit PWUD in the city. Adult individuals reporting frequent psychoactive drug use other than cannabis, with confirmation by urine test, were eligible. Beside HCV and HIV testing, trained peers interviewed participants on their drug consumption and behavior using standardized questionnaires. Fifteen seeds launched the RDSS.

RESULTS

During the 11 weeks of the RDSS, 554 actives PWUD were consecutively included. They were mostly men (78.8%), had a median age of 39 years, and only 25.6% had a stable living place. On average, participants consumed 4.7 (± 3.1) different drugs, and 42.6% smoked free-base cocaine. Unexpectedly, heroin and methamphetamine were consumed by 46.8% and 21.5% of participants, respectively. Among the 194 participants injecting drugs, 33% declared sharing their equipment.

CONCLUSION

This RDSS highlighted a high consumption of heroin, crack and methamphetamine in this PWUD population. These unexpected results can be explained by low attendance to addiction centers, the source of drug use reports. Despite free care and risk reduction equipment in the city, sharing was very frequent among injectors, challenging the current program of harm reduction.

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.

HIV treatment cascade among people who inject drugs in Ukraine

The HIV treatment cascade is an effective tool to track progress and gaps in the HIV response among key populations. People who inject drugs (PWID) remain the most affected key population in Ukraine with HIV prevalence of 22% in 2015. We performed secondary analysis of the 2017 Integrated Bio-Behavioral Surveillance (IBBS) survey data to construct the HIV treatment cascade for PWID and identify correlates of each indicator achievement. The biggest gap in the cascade was found in the first "90", HIV status awareness: only 58% [95% CI: 56%-61%] of HIV-positive PWID reported being aware of their HIV-positive status. Almost 70% [67%-72%] of all HIV-infected PWID who were aware of their status reported that they currently received antiretroviral therapy (ART). Almost three quarters (74% [71%-77%]) of all HIV-infected PWID on ART were virally suppressed. Access to harm reduction services in the past 12 months and lifetime receipt of opioid agonist treatment (OAT) had the strongest association with HIV status awareness. Additionally, OAT patients who were aware of HIV-positive status had 1.7 [1.2-2.3] times the odds of receiving ART. Being on ART for the last 6 months or longer increased odds to be virally suppressed; in contrast, missed recent doses of ART significantly decreased the odds of suppression. The HIV treatment cascade analysis for PWID in Ukraine revealed substantial gaps at each step and identified factors contributing to achievement of the outcomes. More intensive harm reduction outreach along with targeted case finding could help to fill the HIV awareness gap among PWID in Ukraine. Scale up of OAT and community-level linkage to care and ART adherence interventions are viable strategies to improve ART coverage and viral suppression among PWID.

Respondent Driven Sampling for Immigrant Populations: A Health Survey of Foreign-Born Korean Americans

This study examined feasibility and methodological utilities of respondent driven sampling (RDS) for Korean immigrants. We conducted the Health and Life Study of Koreans (HLSK), a Web-based RDS study targeting foreign-born Korean Americans. Through chain referrals, n = 638 participated. Geographic coverage and estimates of HLSK were compared to foreignborn Korean samples in the American Community Survey and the California Health Interview Survey as benchmarks. Compared to the benchmarks, HLSK fared well on the geographic coverage, household type and size, employment and health insurance but over-captured those who were younger, more recent immigrants, with higher education and with disability. Existing RDS-specific estimators were largely ineffective. Conclusions. RDS may serve as a cost-effective tool for recruiting recent immigrants, a harder-to-recruit subgroup within minorities. However, recruitment noncooperation posed operational challenges, a critical gap in the literature. This leaves RDS yet to be a reliable methodology.

Seroepidemiology of syphilis among men who have sex with men in Burkina Faso, West Africa

Men who have sex with men (MSM) have a disproportionate risk of acquiring sexually transmitted infections (STIs), such as syphilis. However, prevalence and determinants of syphilis among this population are less known in West Africa. This study aims to estimate syphilis prevalence among MSM in Burkina Faso. We conducted a cross-sectional biological and behavior survey in the two main cities of Burkina Faso, Ouagadougou and Bobo-Dioulasso. MSM were recruited using Respondent Driven Sampling (RDS) methods. Data were collected from January to April 2013 in Ouagadougou and from May to August 2013 in Bobo-Dioulasso. Out of the 657 MSM screened for syphilis, 6.1% (40/657) tested positive for Treponema pallidum antibodies and 1.1% (7/657) for active syphilis. Population-weighted prevalence of active syphilis was 2.1% (95% CI, 01.1-04.4) in Ouagadougou and 0.0% in Bobo-Dioulasso. Serologic markers of syphilis (anti-Treponema antibodies) were found among 7.4% (95% CI 5.0-10.8) of MSM in Ouagadougou and 5.0% (95% CI 3.1-8.0) in Bobo-Dioulasso. No significant differences were found in syphilis serological markers prevalence by participants' sociodemographic and behavioral characteristics. The prevalence of syphilis among MSM is low and comparable to that of other individuals of reproductive age in Burkina Faso. This low prevalence is very encouraging and suggests implementation of effective public health intervention programs which direct resources and services toward MSM to prevent further spread of syphilis infection and to limit HIV transmission in this group.

Respondent-driven sampling and the homophily configuration graph

Respondent-Driven Sampling (RDS) is a popular method for surveying hard-to-reach populations, especially in the public health domain. Adjusting for the complex sampling mechanism of the RDS procedure is challenging. We propose a new model for the RDS mechanism motivated by a graph model, which we call the Homophily Configuration Graph. Under this model, we develop a new estimator for population proportions that is robust to seed bias, differential activity, differential recruitment and short recruitment chains. We also connect it to existing RDS theory by showing that, if the sample fraction is small, our estimator limits to the popular Salganik-Heckathorn estimator. We perform simulation studies on both empirically observed networks and networks with known statistical properties, suggesting that this new estimator has less bias than currently recommended estimators.

Respondent driven sampling in a biomonitoring study of refugees from Burma in Buffalo, New York who eat Great Lakes fish

BACKGROUND

Refugees from Burma who consume fish caught from local waterbodies have increased risk of exposure to environmental contaminants. We used respondent driven sampling (RDS) to sample this hard-to-reach population for the first Biomonitoring of Great Lakes Populations program. In the current study, we examined the interview data and assessed the effectiveness of RDS to sample the unique population.

METHODS

In 2013, we used RDS to sample 205 Burmese refugees and immigrants residing in Buffalo, New York who consumed fish caught from Great Lakes waters. RDS-adjusted population estimates of sociodemographic characteristics, residential history, fish consumption related behaviors, and awareness of fish advisories were obtained. We also examined sample homophily and equilibrium to assess how well the RDS assumptions were met in the study.

RESULTS

Our sample was diverse with respect to sex, age, years residing in Buffalo, years lived in a refugee camp, education, employment, and fish consumption behaviors, and each of these variables reached equilibrium by the end of recruitment. Burmese refugees in Buffalo consumed Great Lakes fish throughout the year; a majority of them consumed the fish more than two times per week during summer, and about one third ate local fish more than once per week in winter. An estimated 60% of Burmese refugees in Buffalo had heard about local fish advisories.

CONCLUSIONS

RDS has the potential to be an effective methodology for sampling refugees and immigrants in conducting biomonitoring and environmental exposure assessment. Due to high fish consumption and limited awareness and knowledge of fish advisories, some refugee and immigrant populations are more susceptible to environmental contaminants. Increased awareness on local fish advisories is needed among these populations.

Hepatitis C bio-behavioural surveys in people who inject drugs-a systematic review of sensitivity to the theoretical assumptions of respondent driven sampling

Background

New, more effective and better-tolerated therapies for hepatitis C (HCV) have made the elimination of HCV a feasible objective. However, for this to be achieved, it is necessary to have a detailed understanding of HCV epidemiology in people who inject drugs (PWID).

Respondent-driven sampling (RDS) can provide prevalence estimates in hidden populations such as PWID. The aims of this systematic review are to identify published studies that use RDS in PWID to measure the prevalence of HCV, and compare each study against the STROBE-RDS checklist to assess their sensitivity to the theoretical assumptions underlying RDS.

Method

Searches were undertaken in accordance with PRISMA systematic review guidelines. Included studies were English language publications in peer-reviewed journals, which reported the use of RDS to recruit PWID to an HCV bio-behavioural survey. Data was extracted under three headings: (1) survey overview, (2) survey outcomes, and (3) reporting against selected STROBE-RDS criteria.

Results

Thirty-one studies met the inclusion criteria. They varied in scale (range 1–15 survey sites) and the sample sizes achieved (range 81–1000 per survey site) but were consistent in describing the use of standard RDS methods including: seeds, coupons and recruitment incentives.

Twenty-seven studies (87%) either calculated or reported the intention to calculate population prevalence estimates for HCV and two used RDS data to calculate the total population size of PWID. Detailed operational and analytical procedures and reporting against selected criteria from the STROBE-RDS checklist varied between studies. There were widespread indications that sampling did not meet the assumptions underlying RDS, which led to two studies being unable to report an estimated HCV population prevalence in at least one survey location.

Conclusion

RDS can be used to estimate a population prevalence of HCV in PWID and estimate the PWID population size. Accordingly, as a single instrument, it is a useful tool for guiding HCV elimination. However, future studies should report the operational conduct of each survey in accordance with the STROBE-RDS checklist to indicate sensitivity to the theoretical assumptions underlying the method.

Systematic review registration

PROSPERO CRD42015019245

Unveiling of HIV dynamics among transgender women: a respondent-driven sampling study in Rio de Janeiro, Brazil

BACKGROUND

The burden of HIV in transgender women (transwomen) in Brazil remains unknown. We aimed to estimate HIV prevalence among transwomen in Rio de Janeiro and to identify predictors of newly diagnosed HIV infections.

METHODS

We recruited transwomen from Rio de Janeiro, Brazil, by respondent-driven sampling. Eligibility criteria were self-identification as transwomen, being 18 years of age or older, living in Rio de Janeiro or its metropolitan area, and having a valid peer recruitment coupon. We recruited 12 seed participants from social movements and formative focus groups who then used peer recruitment coupons to refer subsequent peers to the study. We categorised participants as HIV negative, known HIV infected, or newly diagnosed as HIV infected. We assessed predictors of newly diagnosed HIV infections by comparing newly diagnosed with HIV-negative participants. We derived population estimates with the Respondent-Driven Sampling II estimator.

FINDINGS

Between Aug 1, 2015, and Jan 29, 2016, we enrolled 345 eligible transwomen. 29·1% (95% CI 23·2-35·4) of participants had no previous HIV testing (adjusted from 60 participants), 31·2% (18·8-43·6) had HIV infections (adjusted from 141 participants), and 7·0% (0·0-15·9) were newly diagnosed as HIV infected (adjusted from 40 participants). We diagnosed syphilis in 28·9% (18·0-39·8) of participants, rectal chlamydia in 14·6% (5·4-23·8), and gonorrhoea in 13·5% (3·2-23·8). Newly diagnosed HIV infections were associated with black race (odds ratio 22·8 [95% CI 2·9-178·9]; p=0·003), travesti (34·1 [5·8-200·2]; p=0·0001) or transsexual woman (41·3 [6·3-271·2]; p=0·0001) gender identity, history of sex work (30·7 [3·5-267·3]; p=0·002), and history of sniffing cocaine (4·4 [1·4-14·1]; p=0·01).

INTERPRETATION

Our results suggest that transwomen bear the largest burden of HIV among any population at risk in Brazil. The high proportion of HIV diagnosis among young participants points to the need for tailored long-term health-care and prevention services to curb the HIV epidemic and improve the quality of life of transwomen in Brazil.

FUNDING

Brazilian Research Council, National Institute of Allergy and Infectious Diseases, Brazilian Sexually Transmitted Disease/AIDS, and Viral Hepatitis Department of the Brazilian Ministry of Health.

A Cross-sectional Survey of HIV Transmission and Behavior among Men Who Have Sex with Men in Different Areas of Inner Mongolia Autonomous Region, China

Background

Little research has been conducted on the human immunodeficiency virus (HIV) epidemic and the sexual intercourse habits of men who have sex with men (MSM) in crowded places, both locally and abroad. This study conducted a survey of MSM in different locales of Inner Mongolia to provide a reference for developing strategies or measures to prevent and control HIV among this understudied population.

Methods

We conducted a cross-sectional survey of men aged 18 years and older at different venues popular among MSM in Inner Mongolia. Between April and July 2012, MSM volunteered to participate in this study, receive HIV/syphilis testing, and complete a questionnaire about their behavior. A total of 1611 MSM participated. Participants signed a voluntary informed consent form, completed an anonymous questionnaire and were tested for HIV and syphilis antibodies.

Results

Of the 1611 MSM surveyed, 6.83 and 23.65 % had HIV and syphilis, respectively, and the co-infection rate was 3.17 %. Sociodemographic factors such as age, culture, marital status, knowledge of acquired immune deficiency syndrome (AIDS) transmission, and peer education significantly differed between venues (P < 0.01). MSM who were under 22 years, 23–35 years, and over 36 years primarily contacted their potential partners online, at bars/other (streetwalkers), and at public baths/parks, respectively. MSM partners found in bars, in public baths, in parks and online were primarily high school students and technical secondary school students. MSM who were streetwalkers or cross-dressing male sex workers primarily had junior middle school education levels or below. Married MSM primarily had intercourse in public baths and parks, and MSM who had intercourse in public baths and parks also reported the greatest proportions of intercourse with women (39.1 and 35.0 %, respectively). Furthermore, MSM who had intercourse in parks reported having the most anal sex with same-sex partners and unprotected intercourse in the past 6 months. Unprotected intercourse with women in the past 6 months was also common among MSM who met partners in bathhouses or online. MSM were most likely to have anal sex with other men in public baths. MSM who had intercourse in bars were the least likely to have used a condom with female partners in the past 6 months. The culture of the MSM who had frequent intercourse with streetwalkers and cross-dressing male sex workers did not predict behavior.

Conclusion

This study indicated that AIDS-related risky behaviors as well as HIV and syphilis infection were associated with the different locations frequented by MSM. When developing intervention strategies for AIDS, it is better to conduct targeted health education and behavioral interventions at bars/online for MSM aged 23–35 years and at public baths/parks for MSM over 36 years. Additionally, the current survey showed that information on AIDS/sexually transmitted diseases (STDs) must be popularized to reach streetwalkers and cross-dressing male sex workers, whose mobility limits their attainment of higher levels of health education.

Update on respondent-driven sampling: Theory and practical considerations for studies of persons who inject drugs

In the last 5 years, more than 600 articles using respondent-driven sampling has been published. This article aims to provide an overview of this sampling technique with an update on the key questions that remain when using respondent-driven sampling, with regard to its application and estimators. Respondent-driven sampling was developed by Heckathorn in 1997 and was based on the principle of individuals recruiting other individuals, who themselves were recruited in previous waves. When there is no sampling frame, respondent-driven sampling has demonstrated its ability to capture individuals belonging to “hidden” or “hard-to-reach” populations in numerous epidemiological surveys. People who use drugs, sex workers, or men who have sex with men are notable examples of specific populations studied using this technique, particularly by public agencies such as the Centers for Disease Control and Prevention in the United States. Respondent-driven sampling, like many others, is based on a set of assumptions that, when respected, can ensure an unbiased estimator. Based on a literature review, we will discuss, among other topics, the effect of violating these assumptions. A special focus is made on surveys of persons who inject drugs. Publications show two major thrusts—methodological and applied researches—for providing practical recommendations in conducting respondent-driven sampling studies. The reasons why respondent-driven sampling did not work for a given population of interest will usually provide important insights for designing health-promoting interventions for that population.

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.

Probability Sampling Method for a Hidden Population Using Respondent-Driven Sampling: Simulation for Cancer Survivors

When there is no sampling frame within a certain group or the group is concerned that making its population public would bring social stigma, we say the population is hidden. It is difficult to approach this kind of population survey-methodologically because the response rate is low and its members are not quite honest with their responses when probability sampling is used. The only alternative known to address the problems caused by previous methods such as snowball sampling is respondent-driven sampling (RDS), which was developed by Heckathorn and his colleagues. RDS is based on a Markov chain, and uses the social network information of the respondent. This characteristic allows for probability sampling when we survey a hidden population. We verified through computer simulation whether RDS can be used on a hidden population of cancer survivors. According to the simulation results of this thesis, the chain-referral sampling of RDS tends to minimize as the sample gets bigger, and it becomes stabilized as the wave progresses. Therefore, it shows that the final sample information can be completely independent from the initial seeds if a certain level of sample size is secured even if the initial seeds were selected through convenient sampling. Thus, RDS can be considered as an alternative which can improve upon both key informant sampling and ethnographic surveys, and it needs to be utilized for various cases domestically as well.

Health Information Seeking, Source Trust, and Culture: A Comparative Analysis of Health Information Trends and Needs Between Guam and the United States

The Guam population offers a unique glimpse into Americans of Pacific Island ancestry and their communication and information-seeking behaviors, experiences, and needs relevant to cancer. National surveys do not typically include the U.S. territories, so there are limited data on the health and cancer information-seeking behaviors of these populations, in which health disparities persist. To fill this information gap, we conducted a survey on health communication in Guam using a modified version of the Health Information National Trends Survey instrument supplemented with items measuring specific cultural factors and communication practices. The results of the survey (N = 511) revealed some differences in health and cancer information-seeking patterns in Guam and the mainland United States. Sociodemographic variables, including sex, age, education, income, and employment, were significantly associated with health and cancer information seeking and Internet use. Levels of trust in various information sources were differentiated in the Guam and mainland U.S.

SAMPLES

Logistic regression models revealed differences in factors predicting health and cancer information seeking and Internet use. The results suggest that these health information-seeking patterns and factors should be taken into account when developing communication strategies for more effective prevention and control programs.

Stigma and Parenting Children Conceived From Sexual Violence

BACKGROUND AND OBJECTIVES

Since armed conflict began in 1996, widespread sexual violence in eastern Democratic Republic of Congo has resulted in many sexual violence-related pregnancies (SVRPs). However, there are limited data on the relationships between mothers and their children from sexual violence. This study aimed to evaluate the nature and determinants of these maternal-child relationships.

METHODS

Using respondent-driven sampling, 757 women raising children from SVRPs in South Kivu Province, Democratic Republic of Congo were interviewed. A parenting index was created from questions assessing the maternal-child relationship. The influences of social stigma, family and community acceptance, and maternal mental health on the parenting index were assessed in univariate and multivariable analyses.

RESULTS

The majority of mothers reported positive attitudes toward their children from SVRPs. Prevalence of perceived family or community stigma toward the women or their children ranged from 31.8% to 42.9%, and prevalence of perceived family or community acceptance ranged from 45.2% to 73.5%. In multivariable analyses, stigma toward the child, as well as maternal anxiety and depression, were associated with lower parenting indexes, whereas acceptance of the mother or child and presence of a spouse were associated with higher parenting indexes (all P ≤ .01).

CONCLUSIONS

In this study with a large sample size, stigma and mental health disorders negatively influenced parenting attitudes, whereas family and community acceptance were associated with adaptive parenting attitudes. Interventions to reduce stigmatization, augment acceptance, and improve maternal mental health may improve the long-term well-being of mothers and children from SVRPs.

Sexually transmitted infections associated with alcohol use and HIV infection among men who have sex with men in Kampala, Uganda

OBJECTIVES

Few studies have been conducted in Africa to assess prevalence of sexually transmitted infections (STIs) and risk factors among men who have sex with men (MSM). We report findings from the first behavioural survey to include STI testing among MSM in Kampala, Uganda.

METHODS

Respondent-driven sampling (RDS) was used to recruit MSM for a biobehavioural survey. Eligible participants were men who reported anal sex with another man in the previous 3 months, were 18 years or older, and resided in Kampala. Information was collected on demographics, sexual behaviour, alcohol and drug use, and STI symptoms. Blood, urine and rectal specimens were tested for syphilis, HIV, rectal and urethral gonorrhoea, and chlamydia. Analyses weighted for RDS were conducted to assess associations with STI diagnosis.

RESULTS

A total of 295 MSM participated in the survey. Almost half (weighted percentage: 47.3%) reported STI symptoms in the last 6 months and 12.9% tested HIV-positive. Prevalence of non-HIV STI was 13.5%; syphilis prevalence was 9.0%. Adjusting for age and education, STI was associated with HIV (adjusted OR (AOR)=3.46, 95% CI 1.03 to 11.64), alcohol use before sex (AOR=4.99, 95% CI 1.86 to 13.38) and having sold sex in the last 3 months (AOR=3.17, 95% CI 1.25 to 8.07), and inversely associated with having anonymous sex partners (AOR=0.20, 95% CI 0.07 to 0.61).

CONCLUSIONS

We observed high levels of self-reported STI symptoms and STI prevalence associated with alcohol use and HIV among MSM in Kampala. Public health interventions supporting MSM are needed to address STI risk and facilitate access to diagnosis and treatment services.

Design and baseline findings of a large-scale rapid response to an HIV outbreak in people who inject drugs in Athens, Greece: the ARISTOTLE programme

AIMS

To (i) describe an intervention implemented in response to the HIV-1 outbreak among people who inject drugs (PWIDs) in Greece (ARISTOTLE programme), (ii) assess its success in identifying and testing this population and (iii) describe socio-demographic characteristics, risk behaviours and access to treatment/prevention, estimate HIV prevalence and identify risk factors, as assessed at the first participation of PWIDs.

DESIGN

A 'seek, test, treat, retain' intervention employing five rounds of respondent-driven sampling.

SETTING

Athens, Greece (2012-13).

PARTICIPANTS

A total of 3320 individuals who had injected drugs in the past 12 months.

INTERVENTION

ARISTOTLE is an intervention that involves reaching out to high-risk, hard-to-reach PWIDs ('seek'), engaging them in HIV testing and providing information and materials to prevent HIV ('test') and initiating and maintaining anti-retroviral and opioid substitution treatment for those testing positive ('treat' and 'retain').

MEASUREMENTS

Blood samples were collected for HIV testing and personal interviews were conducted.

FINDINGS

ARISTOTLE recruited 3320 PWIDs during the course of 13.5 months. More than half (54%) participated in multiple rounds, resulting in 7113 visits. HIV prevalence was 15.1%. At their first contact with the programme, 12.5% were on opioid substitution treatment programmes and the median number of free syringes they had received in the preceding month was 0. In the multivariable analysis, apart from injection-related variables, homelessness was a risk factor for HIV infection in male PWIDs [odds ratio (OR) yes versus no = 1.89, 95% confidence interval (CI) = 1.41, 2.52] while, in female PWIDS, the number of sexual partners (OR for > 5 versus one partner in the past year = 4.12, 95% CI = 1.93, 8.77) and history of imprisonment (OR yes versus no = 2.76, 95% CI = 1.43, 5.31) were associated with HIV.

CONCLUSIONS

In Athens, Greece, the ARISTOTLE intervention for identifying HIV-positive people among people who inject drugs (PWID) facilitated rapid identification of a hidden population experiencing an outbreak and provided HIV testing, counselling and linkage to care. According to ARISTOTLE data, the 2011 HIV outbreak in Athens resulted in 15% HIV infection among PWID. Risk factors for HIV among PWID included homelessness in men and history of imprisonment and number of sexual partners in women.

Characteristics of men who have sex with men in southern Africa who seek sex online: a cross-sectional study

Background

Use of the Internet for finding sexual partners is increasing, particularly among men who have sex with men (MSM). In particular, MSM who seek sex online are an important group to target for human immunodeficiency virus (HIV)/sexually transmitted infection (STI) interventions because they tend to have elevated levels of sexual risk behavior and because the Internet itself may serve as a promising intervention delivery mechanism. However, few studies have examined the correlates of online sexual partner seeking among MSM in sub-Saharan Africa.

Objective

These analyses aim to describe the prevalence of using the Internet to find new male sexual partners among MSM in two southern African countries. In addition, these analyses examine the sociodemographic characteristics, experiences of discrimination and stigma, mental health and substance use characteristics, and HIV-related knowledge, attitudes, and behaviors among MSM associated with meeting sex partners online.

Methods

MSM were enrolled into a cross-sectional study across two sites in Lesotho (N=530), and one in Swaziland (N=322) using respondent-driven sampling. Participants completed a survey and HIV testing. Data were analyzed using bivariate and multivariable logistic regression models to determine which factors were associated with using the Internet to meet sex partners among MSM.

Results

The prevalence of online sex-seeking was high, with 39.4% (209/530) of MSM in Lesotho and 43.8% (141/322) of MSM in Swaziland reporting meeting a new male sexual partner online. In the multivariable analysis, younger age (adjusted odds ratio [aOR] 0.37, 95% confidence interval [CI] 0.27-0.50 per 5 years in Lesotho; aOR 0.68, 95% CI 0.49-0.93 in Swaziland), having more than a high school education (aOR 18.2, 95% CI 7.09-46.62 in Lesotho; aOR 4.23, 95% CI 2.07-8.63 in Swaziland), feeling scared to walk around in public places (aOR 1.89, 95% CI 1.00-3.56 in Lesotho; aOR 2.06, 95% CI 1.23-3.46 in Swaziland), and higher numbers of male anal sex partners within the past 12 months (aOR 1.27, 95% CI 1.01-1.59 per 5 partners in Lesotho; aOR 2.98, 95% CI 1.51-5.89 in Swaziland) were significantly associated with meeting sex partners online in both countries. Additional country-specific associations included increasing knowledge about HIV transmission, feeling afraid to seek health care services, thinking that family members gossiped, and having a prevalent HIV infection among MSM in Lesotho.

Conclusions

Overall, a high proportion of MSM in Lesotho and Swaziland reported meeting male sex partners online, as in other parts of the world. The information in this study can be used to tailor interventions or to suggest modes of delivery of HIV prevention messaging to these MSM, who represent a young and highly stigmatized group. These data suggest that further research assessing the feasibility and acceptability of online interventions will be increasingly critical to addressing the HIV epidemic among MSM across sub-Saharan Africa.

Diagnostics for Respondent-driven Sampling

Respondent-driven sampling (RDS) is a widely used method for sampling from hard-to-reach human populations, especially populations at higher risk for HIV. Data are collected through peer-referral over social networks. RDS has proven practical for data collection in many difficult settings and is widely used. Inference from RDS data requires many strong assumptions because the sampling design is partially beyond the control of the researcher and partially unobserved. We introduce diagnostic tools for most of these assumptions and apply them in 12 high risk populations. These diagnostics empower researchers to better understand their data and encourage future statistical research on RDS.

Differences in HIV risk behaviors among people who inject drugs by gender and sexual orientation, San Francisco, 2012

BACKGROUND

Sharing of drug injection equipment is a well-established risk factor for the transmission of viral infections, such as human immunodeficiency virus (HIV). However, there are multiple mechanisms through which people who inject drugs (PWID) can acquire and transmit HIV. Differences in drug using and sexual behaviors among heterosexual males, males who have sex with males (MSM), and females who inject drugs may explain health disparities.

METHODS

Data were collected in San Francisco by the National HIV Behavioral Surveillance (NHBS) System of PWID in 2012, and were analyzed to compare the sexual behaviors, drug use behaviors, and prevalence of viral infections among heterosexual males, MSM, and females.

RESULTS

Using a weighted analysis for the RDS sampling design, we estimate that 3.7% of heterosexual males who inject drugs, 24.0% of MSM, and 13.0% of females who inject drugs are living with HIV. Females and heterosexual males primarily injected heroin, while MSM primarily injected methamphetamine. MSM were most likely to have received goods or money for sex and have unprotected intercourse.

CONCLUSION

These data demonstrate differences in risk behaviors and prevalence of viral infections among heterosexual males, MSM, and females. The results also suggest that public health programs prioritizing the different populations of PWID are necessary.

Respondent driven sampling is an effective method for engaging methamphetamine users in HIV prevention research in South Africa

BACKGROUND

South Africa, in the midst of the world's largest HIV epidemic, has a growing methamphetamine problem. Respondent driven sampling (RDS) is a useful tool for recruiting hard-to-reach populations in HIV prevention research, but its use with methamphetamine smokers in South Africa has not been described. This study examined the effectiveness of RDS as a method for engaging methamphetamine users in a Cape Town township into HIV behavioral research.

METHODS

Standard RDS procedures were used to recruit active methamphetamine smokers from a racially diverse peri-urban township in Cape Town. Effectiveness of RDS was determined by examining social network characteristics (network size, homophily, and equilibrium) of recruited participants.

RESULTS

Beginning with eight seeds, 345 methamphetamine users were enrolled over 6 months, with a coupon return rate of 67%. The sample included 197 men and 148 women who were racially diverse (73% Coloured, 27% Black African) and had a mean age of 28.8 years (SD=7.2). Social networks were adequate (mean network size >5) and mainly comprised of close social ties. Equilibrium on race was reached after 11 waves of recruitment, and after ≤3 waves for all other variables of interest. There was little to moderate preference for either in- or out-group recruiting in all subgroups.

CONCLUSIONS

Results suggest that RDS is an effective method for engaging methamphetamine users into HIV prevention research in South Africa. Additionally, RDS may be a useful strategy for seeking high-risk methamphetamine users for HIV testing and linkage to HIV care in this and other low resource settings.

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.

Substance abuse treatment utilization, HIV risk behaviors, and recruitment among suburban injection drug users in Long Island, New York

Prevention and treatment of injection drug use remains a public health concern. We used data from the 2005 Centers for Disease Control and prevention National HIV Behavioral Surveillance system to assess substance abuse treatment utilization, risk behaviors, and recruitment processes in a respondent driven sample of suburban injectors. Twelve service utilization and injection risk variables were analyzed using latent class analysis. Three latent classes were identified: low use, low risk; low use, high risk; and high use, moderate/high risk. In multivariate analysis, annual income <$15,000 (adjusted odds ratio (aOR) = 8.19 [95 % confidence interval (CI), 3.83-17.51]) and self-reported hepatitis C virus infection (aOR = 4.32, 95 % CI (1.84-10.17)) were significantly associated with class membership. Homophily, a measure of preferential recruitment showed that injectors with recent treatment utilization appear a more cohesive group than out-of-treatment injectors. Preferentially reaching injection drug users with high risk behaviors and no recent drug treatment history via respondent driven sampling will require future research.

Risk behaviors for HIV in sexual partnerships of San Francisco injection drug users

While injection drug users (IDU) in the USA are known to form sexual partnerships with IDU as well as non-IDU, scientific research is lacking regarding risk behaviors for HIV transmission within these partnerships. Such information could aid HIV-prevention efforts among IDU and could also explain the relatively low prevalence of HIV among non-IDU heterosexuals in US cities such as San Francisco. Using data from a cross-sectional sample of San Francisco IDU we estimated (1) the prevalence of IDU-IDU and IDU-non-IDU sexual partnerships, (2) the frequency of serodiscordant unprotected intercourse in IDU-IDU and IDU-non-IDU sexual partnerships, and (3) the frequency of concurrence of sexual risk and injection-related risk within IDU-IDU sexual partnerships. An estimated 68% of sexually active San Francisco IDU is in IDU-IDU partnerships. Our analysis suggests that compared to IDU-non-IDU partnerships, IDU-IDU partnerships include a greater rate of episodes of serodiscordant unprotected intercourse (incidence rate ratio: 10.2; 95% confidence interval: 2.1-50.7). In fact, our data suggest that 92% of serodiscordant sexual episodes involving IDU are attributable to IDU-IDU pairings. Unprotected intercourse and needle sharing occur concurrently in an estimated 29% of IDU-IDU partnerships. Our data suggest that HIV-transmission risk is higher within IDU-IDU partnerships than it is within IDU-non-IDU partnerships. This disparity could explain the relatively low prevalence of HIV among non-IDU heterosexuals in San Francisco. We recommend that HIV-prevention efforts among IDU continue to address sexual risk behaviors for HIV transmission in addition to injection-related risk behaviors, with emphasis on IDU-IDU partnerships.