Using Respondent-Driven Sampling (RDS) to Identify the Healthcare Needs among Women of Reproductive Age Who Migrated from Venezuela to Brazil, 2018-2021.

In 2021, an RDS survey was conducted among Venezuelan migrant women of reproductive age who migrated to two Brazilian cities (Manaus and Boa Vista) from 2018 to 2021. To start the RDS recruitment, we chose seeds non-randomly in both cities. The study variables were age, educational level, self-rated health, pregnancy, migratory status and use of health services. We estimated the prevalence, confidence intervals and homophily effects by variable category. We used a multivariate logistic regression model to identify the main factors associated with healthcare use. A total of 761 women were recruited in Manaus and 1268 in Boa Vista. Manaus showed more irregular migrants than Boa Vista. The main reasons for using health services were as follows: illness, disease prevention and prenatal care. The logistic regression model showed the use of health services was associated with educational level and healthcare needs but not with migratory status. The social inclusion of Venezuelan migrants is extremely relevant, although many challenges must be overcome. The strategy of the Brazilian Federal Government for providing humanitarian assistance to Venezuelan migrants should be expanded to include and facilitate their integration into labor markets, access to healthcare and education, benefiting both migrants and the Brazilian people by reducing social inequality.

Recruiting hard-to-reach populations via respondent driven sampling for mobile phone surveys in Colombia: a qualitative study.

BACKGROUND: Uptake of mobile phone surveys (MPS) is increasing in many low- and middle-income countries, particularly within the context of data collection on non-communicable diseases (NCDs) behavioural risk factors. One barrier to collecting representative data through MPS is capturing data from older participants.Respondent driven sampling (RDS) consists of chain-referral strategies where existing study subjects recruit follow-up participants purposively based on predefined eligibility criteria. Adapting RDS strategies to MPS efforts could, theoretically, yield higher rates of participation for that age group. OBJECTIVE: To investigate factors that influence the perceived acceptability of a RDS recruitment method for MPS involving people over 45 years of age living in Colombia. METHODS: An MPS recruitment strategy deploying RDS techniques was piloted to increase participation of older populations. We conducted a qualitative study that drew from surveys with open and closed-ended items, semi-structured interviews for feedback, and focus group discussions to explore perceptions of the strategy and barriers to its application amongst MPS participants. RESULTS: The strategy's success is affected by factors such as cultural adaptation, institutional credibility and public trust, data protection, and challenges with mobile phone technology. These factors are relevant to individuals' willingness to facilitate RDS efforts targeting hard-to-reach people. Recruitment strategies are valuable in part because hard-to-reach populations are often most accessible through their contacts within their social network who can serve as trust liaisons and drive engagement. CONCLUSIONS: These findings may inform future studies where similar interventions are being considered to improve access to mobile phone-based data collection amongst hard-to-reach groups.

TransOdara study: the challenge of integrating methods, settings and procedures during the COVID-19 pandemic in Brazil / Estudo TransOdara: o desafio de integrar métodos, contextos e procedimentos durante a pandemia de COVID-19 no Brasil

ABSTRACT Objective Sexually transmitted infections (STIs) disproportionately affect transgender women and travestis (TGW), who often lack access to healthcare due to stigma and discrimination. We describe the approach and methodology of a study investigating the prevalence of syphilis, HIV, hepatitis A, B, and C, Neisseria gonorrhoeae (NG), Chlamydia trachomatis (CT), and human papillomavirus (HPV) among TGW, as well as their knowledge and perceptions regarding syphilis, to better inform policies to curb STIs among this vulnerable population. Methods: TransOdara was a multicentric, cross-sectional study conducted among TGW in five capital cities from major Brazilian regions between December 2019 and July 2021. Self-identified transgender women and travestis aged >18 years were recruited using respondent-driven sampling after a qualitative formative phase, completed an interviewer-led questionnaire, were offered a physical examination, and were also asked to provide samples from multiple sites to detect various STIs, starting vaccination and treatment when indicated. Results: A total of 1,317 participants were recruited from the five study locations: Campo Grande (n=181, 13.7%), Manaus (n=340, 25.8%), Porto Alegre (n=192, 14.6%), Salvador (n=201, 15.3%), and São Paulo (n=403, 30.6%). The recruitment period varied at each study location due to logistic constraints imposed by the COVID-19 pandemic. Conclusion: Despite the enormous challenges posed by the co-occurrence of the COVID-19 pandemic and field work targeting a vulnerable, elusive, and scattered population, the TransOdara project has been effectively implemented. Caveats did not preclude 1,300 TGW from being interviewed and tested, amid a significant epidemic that disrupted health services and research projects in Brazil and worldwide.

RESUMO Objetivo As infecções sexualmente transmissíveis (IST) afetam desproporcionalmente as mulheres trans e travestis (MTT), que muitas vezes não têm acesso a cuidados de saúde devido ao estigma e à discriminação. Descrevemos a abordagem e a metodologia de um estudo que investigou a prevalência de sífilis, HIV, hepatite A, B e C, Neisseria gonorrhoeae (NG), Chlamydia trachomatis (CT) e papilomavírus humano (HPV) entre as MTT, bem como seu conhecimento e percepção sobre a sífilis, para melhor as políticas para redução de IST nessa população vulnerável. Métodos: TransOdara foi um estudo multicêntrico, transversal, realizado em cinco capitais das principais regiões brasileiras entre dezembro de 2019 e julho de 2021. Mulheres autoidentificadas como mulheres trans ou travestis, com idade >18 anos, foram recrutadas usando respondent-driven sampling, após uma fase de pesquisa formativa. Responderam a um questionário conduzido por entrevistadoras. Foi oferecida consulta médica, com exame físico, e solicitou-se que fornecessem amostras de vários locais para detectar as IST citadas. Quando indicado e consentido, foram iniciadas a vacinação e o tratamento. Resultados: Foram recrutadas 1.317 participantes nos cinco locais de estudo: Campo Grande (n=181, 13,7%), Manaus (n=340, 25,8%), Porto Alegre (n=192, 14,6%), Salvador (n= =201, 15,3%) e São Paulo (n=403, 30,6%). O período de recrutamento variou em cada local em razão de restrições logísticas impostas pela pandemia de COVID-19. Conclusão: Apesar dos enormes desafios colocados pela ocorrência simultânea da pandemia da COVID-19 e do trabalho de campo dirigido a uma população vulnerabilizada e dispersa, o projeto TransOdara foi eficazmente implementado. As adversidades não impediram que mais de 1.300 mulheres trans e travestis tenham sido entrevistadas e testadas em meio a uma epidemia de tal magnitude que perturbou os serviços de saúde e os projetos de pesquisa no Brasil e no mundo.

Innovative Strategies for Remotely Sampling Hard-to-Reach Populations: Assessing Phone Versus Internet Respondent-Driven Sampling Approaches Among Venezuelan Refugees and Migrants in Colombia.

It is challenging to quantitatively measure the health vulnerability and risk factors of refugees and migrants residing outside of formal settlement settings. For hard-to-reach populations without available sampling frames, researchers have increasingly turned to novel sampling and statistical methods, like respondent-driven sampling (RDS). "Standard" RDS is typically conducted face-to-face at fixed sites. However, during the coronavirus disease 2019 (COVID-19) pandemic, face-to-face survey methods and recruitment approaches posed high potential risk of virus transmission and infection, making remote RDS approaches optimal. In this paper, we explore the feasibility of implementing telephone and Internet RDS strategies to assess challenges faced by Venezuelan refugees and migrants in the city of Bogotá, Colombia's capital, and the department of Norte de Santander, the main Venezuelan-Colombian border crossing site. We describe RDS assumptions, survey design, formative research, and the implementation of both strategies and present diagnostics for determining whether assumptions are met. Phone-based recruitment strategies in both locations and the Internet strategy in Bogotá achieved their calculated sample size; however, the Internet strategy in Norte de Santander did not. Most RDS assumptions were sufficiently met at sites where sample sizes were reached. These surveys provide valuable lessons for implementing innovative remote strategies with which to study hard-to-reach populations such as refugees and migrants.

Hepatitis B Prevalence among Men Who Have Sex with Men in Brazil.

Hepatitis B virus (HBV) is a global public health problem and requires specific prevention actions, particularly focusing on the key populations, such as men who have sex with men (MSM). We aimed at assessing the prevalence of HBV infection, among MSM, in a multicity study in Brazil. In 2016, we conducted a survey using a respondent-driven sampling methodology in 12 Brazilian cities. Rapid tests (RT) were performed on 3178 samples from those MSM. Positive results were tested for HBV DNA and sequenced. If negative for HBV DNA, samples were tested for serological markers. The prevalence rate of HBV exposure and clearance was 10.1% (95% CI: 8.1-12.6), and 1.1% (95%; CI: 0.6-2.1) were confirmed to be HBsAg-positive. Of those samples tested for anti-HBs (n = 1033), only 74.4% presented a serological profile analogous to that elicited by hepatitis B vaccination. Among HBsAg-positive samples (n = 29), 72.4% were HBV DNA-positive, and from these, 18 were sequenced. HBV genotypes A, F, and G were found in 55.5%, 38.9%, and 5.6%, respectively. This study indicates high prevalence rates of MSM HBV exposure and a low positivity index for the serological marker of HBV vaccine immunity. These findings may contribute to the discussion of strategies to prevent hepatitis B and reinforce the importance of promoting HBV vaccination in this key population.

Gynecological Care Among Brazilian Women Who Have Sex with Women: A Respondent-Driven Sampling Study.

Purpose: This study aimed to describe the gynecological care provided to Brazilian women who have sex with women (WSW). Methods: Respondent-driven sampling was used to recruit Brazilian WSW. The survey questions, concerning gynecological care, were designed in Portuguese by medical professionals, medical students, and LGBTQIA+ community members, including the authors. The statistical analyses were weighted to account for the likelihood of recruitment. Results: From January to August of 2018, 299 participants were recruited in 14 recruitment waves. The mean age of the WSW was 25.3 years. Most (54.9%) identified as lesbian and had been involved in past-year sexual intercourse mainly with cisgender women (86.1%). The WSW also reported having sex with cisgender men (22.2%), transgender men (5.3%), nonbinary people (2.3%), and transgender women (5.3%) in the last year. More than a quarter of the WSW did not have regular appointments with a gynecologist: 8.0% (95% confidence interval [CI] = 4.2-11.6) and 19% (95% CI = 12.8-25.2) stated that they had never gone to the gynecologist or they had only gone for emergencies, respectively. Almost one-third had never had cervical cancer screening (cervical cytology, Pap test or Pap smear). Most women justified avoiding the test because they felt healthy, thought it would hurt, or feared a health professional might mistreat them. Conclusion: Gynecologists should avoid heteronormative assumptions, inquire about sexual practices, orientation, and identity separately, and provide Pap tests as advised to WSW.

Provider-Initiated HIV Testing in Puerto Rico from Data of the National HIV Behavioral Surveillance-Heterosexual Cycle (NHBS-HET) 2016: National Cross-sectional Survey.

BACKGROUND: According to the Centers for Disease Control and Prevention and World Health Organization guidelines, all individuals aged 13-64 years should get screened for HIV infection as part of their routine medical examinations. Individuals at high risk should get tested annually. OBJECTIVE: This study aimed to identify the sociodemographic, health care, and sexual behavioral characteristics of provider-initiated HIV testing using data from the Puerto Rico National HIV Behavioral Surveillance 2016 cycle, directed toward heterosexual individuals at increased risk of HIV infection. METHODS: A sample of 358 eligible participants were recruited through respondent-driven sampling, where sociodemographic characteristics, health care use, and HIV test referral were used to assess a description of the study sample. Pearson chi-square and Fisher tests were used to evaluate proportional differences. Multivariate logistic regression models were performed to determine the association between independent variables and HIV test referral. Adjusted prevalence ratios by sex and age with their 95% CIs were determined using a statistical significance level of .05. RESULTS: Despite 67.9% (243/358) of participants showing high-risk sexual behavioral practices and 67.4% (236/350) reporting a low perceived risk of HIV infection among those who visited a health care provider within the last 12 months, 80.7% (289/358) of the study sample did not receive an HIV test referral at a recent medical visit. Multivariate analysis showed that the estimated prevalence of the participants who received an HIV test referral among those who reported being engaged in high-risk sexual behaviors was 41% (adjusted prevalence ratio .59, 95% CI .39-.91; P=.02) lower than the estimated prevalence among those who did not engage in high-risk sexual behavior. CONCLUSIONS: This sample of Puerto Rican adults reported a significantly lower prevalence of receiving an HIV test referral among heterosexual individuals at increased risk of HIV infection who engaged in high-risk behaviors. This study further emphasizes the need for health care providers to follow recommended guidelines for HIV test referrals in health care settings. Promotion practices in the future should include enhancing referral and access to HIV tests and implementing preventive measures to counteract the HIV epidemic in Puerto Rico.

Sexual Violence and Low Rates of HIV Post-exposure Prophylaxis Access Among Female Sex Workers in Brazil.

Female sex workers (FSW) are disproportionately affected by sexual violence (SV) and HIV. Social and structural barriers limit their access to post-exposure prophylaxis (PEP). Respondent-driven sampling survey in 12 Brazilian cities among 4188 FSW aimed to estimate the rates of SV and factors associated with access to PEP use among FSW who experienced SV. The prevalence of SV was 26.3% (1199). Of the 1199, 7.5% sought out healthcare and used PEP, 19% sought out healthcare, but did not use PEP, and 73.5% did not seek out healthcare after SV. Factors associated with PEP use included PEP awareness, participation in HIV/STI prevention workshops, and disclosure of FSW status in healthcare services. Although Brazil has a PEP program free of charge, it is not readily accessible, even for FSW who seek out healthcare. The development of effective strategies to link FSW to HIV preventive services is urgently needed.

RESUMEN: Mujeres trabajadoras sexuales (MTS) se ven afectadas de manera desproporcionada por la violencia sexual (VS) y el VIH. Las barreras sociales y estructurales limitan su acceso a la profilaxis posexposición (PEP). Encuesta de muestreo dirigida por encuestados en 12 ciudades brasileñas con 4188 MTS para estimar la prevalencia de VS y los factores asociados al uso de PEP entre MTS que experimentaron VS. La prevalencia de VS fue del 26.3% (1199). De essas, el 7.5% buscó atención médica y usó PEP, el 19% buscó atención médica pero no usó PEP y el 73.5% no buscó atención después del SV. Factores asociados con el uso de PEP: conciencia de PEP; participación en talleres educativos y divulgación del trabajo en los servicios de salud. Aunque Brasil tiene un programa de PEP gratuito, no es de fácil acceso. Es urgente el desarrollo de estrategias efectivas para vincular las MTS con servicios de prevención.

HIV Surveillance and Research for Migrant Populations: Protocol Integrating Respondent-Driven Sampling, Case Finding, and Medicolegal Services for Venezuelans Living in Colombia.

BACKGROUND: Epidemiologic research among migrant populations is limited by logistical, methodological, and ethical challenges, but it is necessary for informing public health and humanitarian programming. OBJECTIVE: We describe a methodology to estimate HIV prevalence among Venezuelan migrants in Colombia. METHODS: Respondent-driven sampling, a nonprobability sampling method, was selected for attributes of reaching highly networked populations without sampling frames and analytic methods that permit estimation of population parameters. Respondent-driven sampling was modified to permit electronic referral of peers via SMS text messaging and WhatsApp. Participants complete sociobehavioral surveys and rapid HIV and syphilis screening tests with confirmatory testing. HIV treatment is not available for migrants who have entered Colombia through irregular pathways; thus, medicolegal services integrated into posttest counseling provide staff lawyers and legal assistance to participants diagnosed with HIV or syphilis for sustained access to treatment through the national health system. Case finding is integrated into respondent-driven sampling to allow partner referral. This study is implemented by a local community-based organization providing HIV support services and related legal services for Venezuelans in Colombia. RESULTS: Data collection was launched in 4 cities in July and August 2021. As of November 2021, 3105 of the target 6100 participants were enrolled, with enrollment expected to end by February/March 2022. CONCLUSIONS: Tailored methods that combine community-led efforts with innovations in sampling and linkage to care can aid in advancing health research for migrant and displaced populations. Worldwide trends in displacement and migration underscore the value of improved methods for translation to humanitarian and public health programming. INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): DERR1-10.2196/36026.

Respondent-driven sampling: Advantages and disadvantages from a sampling method. / Respondent-driven sampling: ventajas e inconvenientes de un método de muestreo.

This article summarizes the main elements, advantages, and disadvantages of Respondent-driven Sampling (RDS). Some criticisms regarding the feasibility of the inherent assumptions, their point estimators, and the obtained variances are pointed out. This article also comments on the problems observed in the quality of reports. Surveys using RDS should be methodologically sound as they are being applied to define priorities in health programs and develop national and international policies for financing service delivery, among other uses. However, there is considerable potential for bias related to implementation and analytical errors. There is limited empirical evidence on how representative the results obtained by RDS are, and the quest to improve the methodology is still in progress. Nevertheless, to have confidence in RDS results, we must verify that the social structure of the networks conforms to the assumptions required by the theory, that the sampling assumptions are reasonably fulfilled, and that the quality of the report is optimal, particularly for methodological and analytical items.

Este artículo resume algunas consideraciones, ventajas e inconvenientes de esta técnica de muestreo conocida como Respondent-driven Sampling (RDS). Se señalan algunas críticas que han aparecido en la literatura científica respecto a la viabilidad de los supuestos inherentes a esta técnica y, en consecuencia, respecto a los estimadores puntuales y de las varianzas así obtenidas. También, se comentan los problemas observados en la literatura acerca de la calidad de los reportes de este tipo de estudios. Las encuestas que utilizan RDS deben ser metodológicamente de buena calidad, pues están siendo aplicadas extensamente para definir prioridades de programas sanitarios, para desarrollar políticas nacionales e internacionales de financiamiento de prestación de servicios, entre otras aplicaciones. Sin embargo, existe un amplio potencial de sesgo al usar este método, muchos de los cuales están relacionados con la implementación y los errores analíticos. La evidencia empírica sobre cuán representativos son los resultados obtenidos mediante RDS es limitada, y la búsqueda para mejorar la metodología es un área de investigación aún en progreso. No obstante, para tener confianza en los resultados publicados debe verificarse que la estructura social de las redes estudiadas se ajusta a los supuestos requeridos por la teoría de RDS, que los supuestos del muestreo se cumplen razonablemente y que la calidad del reporte es óptima, en particular respecto a los ítems metodológicos y analíticos.

Polydrug Use and Co-occurring Substance Use Disorders in a Respondent Driven Sampling of Cocaine Base Paste Users in Santiago, Chile.

We characterized substance use patterns and co-occurring substance use disorders among active cocaine base paste (CBP) users in Santiago, Chile using data from respondent-driven sampling (RDS) in three areas of Metropolitan Santiago. Recruitment began with nine seeds, reaching 398 active CBP users (18% women; mean age 37.7 years), defined as persons consuming CBP at least twice per week in the last three months. Population proportions and uncertainty were estimated accounting for individuals' social network and homophily. The median CBP age of initiation was 21 years, and the median number of years using CBP was 7 for women and 15 for men. The median days of use in the past month was 25 days, with a median of 56 doses per week. The proportion of monthly income spent on CBP was 65%. The prevalence of substance use disorders (SUDs) were: 98% for CBP, 67% for alcohol, 60% for marijuana, and 41% for cocaine hydrochloride. Heavy polydrug use patterns and co-occurring SUDs are frequent among active CBP users in the metropolitan area of Santiago. Traditional surveillance strategies may have underestimated polysubstance use and co-occurring SUDs in active CBP users. RDS proved to be a feasible methodology that could be effectively used for substance use surveillance among hard-to-reach populations.

Exploring HIV risk behavior and sexual/gender identities among transgender women and their sexual partners in Peru using respondent-driven sampling.

HIV prevalence is high among transgender women, but little is known about cisgender men who have sex with transgender women (MSTW). The objective of this study was to investigate characteristics and behavior of MSTW compared to transgender women and men who have sex with men (MSM) using a modified respondent-driven sampling design. Seed participants completed a survey and invited up to three sex partners. Forward recruitment continued in waves through the referral of sex partners. Cross-sectional data were assessed using mixed effects models. From February to July 2018, 479 participants in Lima, Peru enrolled (n = 199 transgender women, n = 196 MSTW, and n = 45 MSM). MSTW behavior and identity differed significantly from that of transgender women and MSM. MSTW primarily identified as bisexual (69%) or heterosexual (15%) and only 6% reported male partners. Insertive condomless anal intercourse was reported by 61% of MSTW; 46% did not know their HIV serostatus. Compared to MSTW without male partners, those with recent male partners were more likely to sell sex (OR 15.7, 95% CI 4.1-60.5), and report condomless receptive anal intercourse (OR 89.0, 95% CI 19.1-414.8). This evidence suggests that MSTW are a distinct population from MSM, and highlights the critical need to include MSTW in HIV research and interventions.

A comparison of the effectiveness of respondent-driven and venue-based sampling for identifying undiagnosed HIV infection among cisgender men who have sex with men and transgender women in Tijuana, Mexico.

BACKGROUND: Efforts to increase HIV testing, diagnosis and care are critical to curbing HIV epidemics among cisgender men who have sex with men (MSM) and transgender women (TW) in low- and middle-income countries (LMIC). We compared the effectiveness of respondent-driven sampling (RDS) and venue-based sampling (VBS) for identifying previously undiagnosed HIV infection among MSM and TW in Tijuana, Mexico. METHODS: Between March 2015 and December 2018, we conducted RDS within the social networks of MSM and TW and VBS at venues frequented by MSM and TW to socialize and meet sexual partners. Those reached by RDS/VBS who reported at least 18 years of age, anal sex with MSM or TW, and no previous HIV diagnosis were eligible for HIV testing. RESULTS: Of those screened following recruitment via RDS (N = 1232; 98.6% MSM; 1.3% TW), 60.8% (749/1232) were eligible for HIV testing and 97.5% (730/749) were tested for HIV infection, which led to the identification of 36 newly diagnosed HIV infections (4.9%). Of those screened following recruitment via VBS (N = 2560; 95.2% MSM; 4.6% TW), 56.5% (1446/2560) were eligible for HIV testing and 92.8% (1342/1446) were tested for HIV infection, which led to the identification of 82 newly diagnosed HIV infections (6.1%). The proportion of new HIV diagnoses did not differ by recruitment method (ratio = 0.81, 95% confidence interval: 0.55 to 1.18). Compared to those recruited via RDS, those tested following recruitment via VBS were younger, more likely to identify as gay, and more likely to identify as TW. Compared to those recruited via VBS, those newly diagnosed with HIV infection following recruitment via RDS reported higher levels of internalized stigma and were more likely to report injection drug use and a history of deportation from the United States. CONCLUSIONS: Despite RDS and VBS being equally effective for identifying undiagnosed HIV infection, each recruitment method reached different subgroups of MSM and TW in Tijuana. Our findings suggest that there may be benefits to using both RDS and VBS to increase the identification of previously undiagnosed HIV infection and ultimately support HIV care engagement among MSM and TW in Mexico and other similar LMIC.

Acceptability of HIV self-testing is low among men who have sex with men who have not tested for HIV: a study with respondent-driven sampling in Brazil.

BACKGROUND: Brazil has many people living with HIV (PLWH) who are unaware of their serostatus. The public health system has recently added HIV self-testing (HIVST) for key populations such as men who have sex with men (MSM). This study estimates HIVST acceptability among Brazilian MSM and explores factors associated with acceptability among MSM who have never tested for HIV or who had a previous negative result. METHODS: Respondent-driven sampling (RDS) was used to recruit 4176 MSM in 12 Brazilian cities in 2016 to this biological and behavioral surveillance study. We excluded from this analysis all MSM who were aware of their positive HIV serostatus. Descriptive, bivariate and multivariate analyses were conducted. Overall proportions were weighted with Gile's estimator in RDS Analyst software and 95% confidence intervals were calculated. The analyses of HIVST acceptability were stratified by prior HIV testing (never or one or more times). RESULTS: For this analysis, 3605 MSM were included. The acceptability of HIVST was 49.1%, lower among those who had never tested for HIV (42.7%) compared to those who had a previous HIV negative test (50.1%). In the subgroup of MSM who had never tested for HIV, those who reported discrimination or who had a medical appointment in the last 12 months reported higher HIVST acceptability. Among MSM who had a previous negative HIV test, only those reporting condomless receptive anal sex reported higher HIVST acceptability. In addition, we observed that high levels of knowledge of HIV/AIDS, taking part in lesbian, gay, bisexual, and transgender nongovernmental organizations (LGBT-NGO), or complete secondary or incomplete higher undergraduate education reported higher acceptability. CONCLUSIONS: The acceptability of HIVST was low among MSM, especially among those who never tested for HIV. Given access to HIVST in Brazil, we point to the need for programs that enhance promotion of testing addressed to MSM.

Application of the Respondent-Driven Sampling methodology in a biological and behavioral surveillance survey among female sex workers, Brazil, 2016 / Aplicação da metodologia Respondent-Driven Sampling em pesquisa biológica e comportamental com mulheres trabalhadoras do sexo, Brasil, 2016

ABSTRACT Introduction: Respondent-Driven Sampling (RDS) has been used in surveys with key populations at risk of HIV infection, such as female sex workers (FSW). This article describes the application of the RDS method among FSW in 12 Brazilian cities, during a survey carried out in 2016. Methodology: A biological and behavioral surveillance study carried out in 12 Brazilian cities, with a minimum sample of 350 FSW in each city. Tests were performed for HIV, syphilis, and hepatitis B and C infections. A social-behavioral questionnaire was also applied. Results: The sample was comprised of 4,328 FSW. For data analysis, the sample was weighted according to each participant's network size (due consideration to the implications of RDS complex design and to the effects of homophilia are recommended). Discussion: Although RDS methods for obtaining a statistical sample are based on strong statistical assumptions, allowing for an estimation of statistical parameters, with each new application the method has been rethought. In the analysis of whole-sample data, estimators were robust and compatible with those found in 2009. However, there were significant variations according to each city. Conclusion: The achieved sample size was of great relevance for assessing progress and identifying problems regarding the prevention and treatment of Sexually Transmitted Infections. New RDS studies with more time and operational resources should be envisaged. This could further network development.

RESUMO Introdução: O método de amostragem Respondent-Driven Sampling (RDS) tem sido utilizado em inquéritos com populações-chave sob maior risco de infecção pelo HIV, como as mulheres trabalhadoras do sexo (MTS). Este artigo tem o objetivo de descrever a implementação do RDS entre MTS em 12 cidades brasileiras em 2016. Metodologia: Trata-se de um estudo de vigilância biológica e comportamental realizado em 12 cidades brasileiras, com amostra mínima de 350 MTS em cada cidade. Foram realizados testes para infecções por HIV, sífilis, hepatites B e C, e aplicou-se questionário sociocomportamental. Resultados: Participaram 4.328 MTS. Para a análise dos dados, foi elaborada uma ponderação amostral considerando o tamanho da rede de cada participante; recomenda-se que o desenho complexo de amostragem por RDS e o efeito de homofilia sejam considerados. Discussão: Apesar de o RDS ser fundamentado em pressupostos estatísticos para obtenção de uma amostra probabilística e possibilitar estimação de parâmetros estatísticos, ele vem sendo repensado a cada nova aplicação. Na análise dos dados na totalidade da amostra, os estimadores mostraram-se robustos e coerentes aos encontrados em 2009. Entretanto, constataram-se grandes variações por cidade. Conclusão: O tamanho amostral alcançado foi de grande relevância para avaliar avanços e identificar problemas a respeito da prevenção e assistência às infecções sexualmente transmissíveis. Ressalta-se a necessidade de pensar estudos RDS com maior tempo e recursos para implementação, o que poderia permitir um melhor desenvolvimento das redes.

HIV Prevalence, Knowledge, Attitudes, and Practices Among Polydrug Users in Brazil: A Biological Survey Using Respondent Driven Sampling.

Brazil has a concentrated HIV epidemic among key populations. In 2009, the Ministry of Health conducted a survey in 10 Brazilian cities aiming to estimate HIV prevalence, knowledge, and associated risk behaviors of polysubstance users (PSU). Using Respondent Driven Sampling (RDS), 3449 PSU were recruited, answered an Audio-Computer Self Assisted Interview (ACASI) and were tested for HIV and syphilis. Analyses were weighted by individual's social network size generated on RDSAT. Pooled HIV prevalence was 5.8% but varied across cities. Most PSU were male, non-white, without income, unemployed, with low levels of education. Overall, 12.0% used injectable drugs, 48.7% had sex with occasional partners and 46.4% engaged in commercial sex. A majority received free condoms (71.4%) but 76.7% exhibited inconsistent condom use. Findings can support policies aiming to improve health care and preventive interventions tailored to this population that remains at high risk of acquiring and transmitting HIV/STI in multiple scenarios.

Associations of HIV Testing, Sexual Risk and Access to Prevention Among Female Sex Workers in the Dominican Republic.

The Caribbean region has one of the highest proportions of HIV in the general female population attributable to sex work. In 2008 (n = 1256) and 2012 (n = 1525) in the Dominican Republic, HIV biological and behavioral surveys were conducted among female sex workers (FSW) in four provinces using respondent driven sampling. Participants were ≥15 years who engaged in intercourse in exchange for money in the past 6 months and living/working in the study province. There were no statistically significant changes in HIV and other infections prevalence from 2008 to 2012, despite ongoing risky sexual practices. HIV testing and receiving results was low in all provinces. FSW in 2012 were more likely to receive HIV testing and results if they participated in HIV related information and education and had regular checkups at health centers. Further investigation is needed to understand barriers to HIV testing and access to prevention services.

Cannabis consumption patterns among frequent consumers in Uruguay.

BACKGROUND: In 2013, Uruguay became the first country to fully regulate the cannabis market, which now operates under state control. Cannabis can be legally acquired in three ways: growing it for personal use (self-cultivation), cannabis club membership, and from pharmacies (not yet implemented). Users must be entered into a confidential official registry to gain access. METHODS: This article presents findings of a Respondent Driven Sample survey of 294 high-frequency cannabis consumers in the Montevideo metropolitan area. RESULTS: Frequent consumers resort to more than one method for acquiring cannabis, with illegal means still predominating after 1 year of the new regulation law. Cannabis users overwhelmingly support the current regulation, but many of them are reluctant to register. CONCLUSIONS: Some of the attitudes and behaviors of the high-frequency consumers pose a challenge to the success of the cannabis law. Individuals relying on more than one method of access defy the single access clause, a prerequisite for legal use, while the maximum amount of cannabis individuals can access monthly seems too high even for most frequent consumers, which might promote the emergence of a grey market. Reluctance to register among a significant proportion of high-frequency consumers raises doubts about the law's ability to achieve its stated objectives.

HIV testing among men who have sex with men in Tijuana, Mexico: a cross-sectional study.

OBJECTIVES: HIV testing is critical to the delivery of comprehensive HIV prevention and care services, yet coverage of sexual minorities by HIV testing programmes remains insufficient in many low- and middle-income countries, including Mexico. The objective of this study was to identify the prevalence and correlates of HIV testing among men who have sex with men (MSM) in Tijuana, Mexico. METHODS: We conducted a cross-sectional study (2012-2013) among 189 MSM recruited via respondent-driven sampling (RDS). RDS-weighted logistic regression was used to identify correlates of prior HIV testing. RESULTS: RDS-adjusted prevalence of prior and recent (≤ 12 months) HIV testing was 63.5% (95% CI 51.9% to 73.5%) and 36.8% (95% CI 25.4% to 46.4%), respectively. Prior HIV testing was positively associated with older age (adjusted OR (AOR)=1.09, 95% CI 1.04 to 1.15), being born in Tijuana (AOR=2.68, 95% CI 1.05 to 6.86), higher levels of education (AOR=2.65, 95% CI 1.08 to 6.53), identifying as homosexual or gay (AOR=3.73, 95% CI 1.48 to 9.42), being more 'out' about having sex with men (AOR=1.28, 95% CI:1.02 to 1.62), and a history of sexual abuse (AOR=3.24, 95% CI 1.06 to 9.86). Prior HIV testing was negatively associated with reporting more condomless anal intercourse acts (past 2 months) (AOR=0.95, 95% CI 0.92 to 0.98) and greater internalised homophobia (AOR=0.92, 95% CI 0.86 to 0.99). CONCLUSIONS: Our findings indicate an urgent need for expanded HIV testing services for MSM in Tijuana. Innovative, non-stigmatising, confidential HIV testing interventions targeted at young, less educated, migrant and non-gay identifying MSM may facilitate HIV testing and timely linkage to HIV care and treatment within this population.

Prevalence and correlates of HIV among men who have sex with men in Tijuana, Mexico.

INTRODUCTION: Men who have sex with men (MSM) in developing countries such as Mexico have received relatively little research attention. In Tijuana, Mexico, a border city experiencing a dynamic HIV epidemic, data on MSM are over a decade old. Our aims were to estimate the prevalence and examine correlates of HIV infection among MSM in this city. METHODS: We conducted a cross-sectional study of 191 MSM recruited through respondent-driven sampling (RDS) in 2012. Biological males over the age of 18 who resided in Tijuana and reported sex with a male in the past year were included. Participants underwent interviewer-administered surveys and rapid tests for HIV and syphilis with confirmation. RESULTS: A total of 33 MSM tested positive for HIV, yielding an RDS-adjusted estimated 20% prevalence. Of those who tested positive, 89% were previously unaware of their HIV status. An estimated 36% (95% CI: 26.4-46.5) had been tested for HIV in the past year, and 30% (95% CI: 19.0-40.0) were estimated to have ever used methamphetamine. Independent correlates of being infected with HIV were methamphetamine use (odds ratio [OR] = 2.24, p = 0.045, 95% CI: 1.02, 4.92) and active syphilis infection (OR = 4.33, p = 0.01, 95% CI: 1.42, 13.19). CONCLUSIONS: Our data indicate that MSM are a key sub-population in Tijuana at higher risk for HIV. Tijuana would also appear to have the highest proportion among upper-middle-income countries of HIV-positive MSM who are unknowingly infected. More HIV prevention research on MSM is urgently needed in Tijuana.