Sampling studies to estimate the HIV prevalence rate in female commercial sex workers

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.

Correlates of HIV self-testing among female sex workers in China: implications for expanding HIV screening

Background

Human immunodeficiency virus (HIV) self-testing may help improve test uptake among female sex workers. China has implemented many HIV self-testing programs among men who have sex with men, creating an opportunity for promotion among female sex workers. However, there is a limited literature on examining HIV self-testing among female sex workers. This study aimed to examine HIV self-testing experiences and its determinants among female sex workers in China.

Methods

A venue-based, cross-sectional study was conducted among Chinese female sex workers in 2019. Participants completed a survey including social-demographic characteristics, sexual behaviors, and HIV self-testing history, the distribution of which were analyzed using descriptive analysis. Multivariable logistic regression was conducted to identify associations with HIV self-testing.

Results

Among 1287 Chinese female sex workers, 1072 (83.3%, 95% confidence interval [CI] 81.2–85.3%) had ever tested for HIV, and 103 (8.0%, 95% CI 6.6–9.6%) had ever used HIV self-testing. More than half reported that the self-test was their first HIV test (59.2%, 61/103), around one-fifth reported HIV self-testing results influenced the price of sex (21.4%, 22/103). A minority of individuals reported ever experiencing pressure to undertake HIV self-testing (6.8%, 7/103). After adjusting for covariates, HIV self-testing was positively associated with receiving anal sex in the past month (adjusted odds ratio [aOR] = 2.2, 95% CI 1.4–3.5), using drugs before or during sex (aOR = 2.8, 95% CI 1.8–4.5), injecting drugs in the past 6 months (aOR = 2.6, 95% CI 1.2–6.0), being diagnosed with other sexually transmitted infections (aOR = 1.6, 95% CI 1.0–2.5), tested for other sexually transmitted infections in the past six months (aOR = 3.4, 95% CI 2.1–5.5), ever tested in the hospital (aOR = 3.4, 95% CI 2.0–5.6), and ever tested in the community (aOR = 1.5, 95% CI 1.2–1.9).

Conclusions

Our findings suggest that HIV self-testing could expand overall HIV testing uptake, increase HIV testing frequency, reach sub-groups of high-risk female sex workers and has limited potential harms among female sex workers. HIV self-testing should be incorporated among Chinese female sex workers as a complement to facility-based HIV testing services.

Effect of community active case-finding strategies for detection of tuberculosis in Cambodia: study protocol for a pragmatic cluster randomized controlled trial

Background

Cambodia has made notable progress in the fight against tuberculosis (TB). However, these gains are impeded by a significant proportion of undiagnosed cases. To effectively reach people with TB, active case-finding (ACF) strategies have been adopted by countries affected by the epidemic, including Cambodia, alongside passive case finding (PCF). Despite increased efforts to improve case detection, approximately 40% of TB cases in Cambodia remained undiagnosed in 2018. In Cambodia, several community-based TB ACF modalities have been implemented, but their effectiveness has yet to be systematically assessed.

Methods

This pragmatic cluster randomized controlled trial will be conducted between December 2019 and June 2021. We will randomize eight operational districts (clusters) in seven provinces (Kampong Cham, Kampong Thom, Prey Veng, Thbong Khmum, Kampong Chhnang, Kandal, and Kampong Speu) to either the control group (PCF) or the intervention groups (ACF using a seed-and-recruit model, ACF targeting household and neighborhood contacts, and ACF targeting persons aged ≥ 55 years using mobile screening units). The primary endpoints will be TB case notification rates, additionality, and cumulative yield of TB cases. The secondary endpoints include treatment outcomes, the number needed to screen to find one TB case, and cost-effectiveness outcome measures. We will analyze the primary and secondary endpoints by intention to treat. We will compare cluster and individual-level characteristics using Student’s t test and hierarchical or mixed-effect models to estimate the ratio of these means. The incremental cost-effectiveness ratio per disability-adjusted life year averted will also be considered as a benchmark to determine whether the interventions are cost-effective.

Discussion

This study will build an evidence base to inform future scale-up, implementation, and sustainability of ACF strategies in Cambodia and other similar settings. Implementation of this study will also complement TB control strategies in Cambodia by conducting ACF in operational districts without active interventions to find TB cases currently. Those who are ill and might have TB will be promptly screened, diagnosed, and linked to care. Early diagnosis and treatment initiation will also benefit their community by interrupting transmission and prevent further infections. The experience gained from this project will inform future attempts in conducting pragmatic trials in low-resource settings.

Trial registration

ClinicalTrials.gov, NCT04094350. Registered on 18 September 2019.

Application of the Respondent-Driven Sampling methodology in a biological and behavioral surveillance survey among female sex workers, Brazil, 2016

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.

Prevalence estimates of HIV, syphilis, hepatitis B and C among female sex workers (FSW) in Brazil, 2016

BACKGROUND

Female sex workers (FSW) bear a high burden of sexually transmitted infections (STI). In this paper, we estimate the prevalence of human immunodeficiency virus (HIV), HBV = hepatitis B virus (HBV), HCV = hepatitis C virus (HCV), syphilis and co-infections in the second Biological and Behavioral Surveillance Survey among FSW in Brazil.

METHOD

The survey was conducted in 12 Brazilian cities from July to November 2016. We used respondent-driven sampling (RDS) to recruit 350 FSW in each city. Rapid tests were used for screening HIV, syphilis, HCV, and HBV. Confirmatory tests were performed on all samples with reactive rapid test result. All testing algorithms and interpretations were done according to the recommendations of the Department of STI/AIDS and viral hepatitis, Ministry of Health. The STI diagnoses were given by: confirmed HIV infection by a positive result on Western blot; active syphilis infection, defined by a RPR titer equal or greater than 1/8; viremia period of HBV and HCV infections, characterized by a detectable (or quantifiable) viral load. Prevalence estimates and standard errors were calculated using statistical procedures suitable for data collected by RDS.

RESULTS

Excluding the seeds, 4245 FSW were enrolled. Prevalence estimates were: HIV 5.3% (95% CI: 4.4%-6.2%); active syphilis 8.5% (95% CI: 7.3%-9.7%); HBV 0.4% (95% CI: 0.2%-0.7%); and, HCV 0.9% (95% CI: 0.6%-1.3%). Among the 4154 FSW tested for the 4 infections, 13.3%; (95% CI 12.0%-14.8%) were diagnosed with at least one of the infections, of which 87.6% (95% CI: 83.3%-90.9%) had single infections. The prevalence of HIV/syphilis co-infection was 1.09% (95% CI: 0.7%- 1.6%) and of HIV/HCV or HBV infections was 0.4% (95% CI: 0.2%-0.7%).

CONCLUSIONS

Our results reveal the need to conduct more studies to estimate the prevalence of STI and co-infections among FSW in Brazil. Longitudinal trends in the prevalence estimates of HIV and other STI provide information to monitor changes in this high-risk population. Additionally, the study highlights the importance of measuring the hepatitis burden among FSW living with HIV, and the need of including FSW in all aspects of STI prevention, care, and treatment programs.

Factors associated with HIV infection among female sex workers in Brazil

BACKGROUND

Female sex workers (FSWs) are one of the most-at-risk population groups for human immunodeficiency virus (HIV) infection. This paper aims at identifying the main predictors of HIV infection among FSW recruited in the 2nd Biological and Behavioral Surveillance Survey in 12 Brazilian cities in 2016.

METHOD

Data were collected on 4245 FSW recruited by respondent driven sampling (RDS). Weights were inversely proportional to participants' network sizes. To establish the correlates of HIV infection, we used logistic regression models taking into account the dependence of observations resultant from the recruitment chains. The analysis included socio-demographic sex work characteristics, sexual behavior, history of violence, alcohol and drug use, utilization of health services, and occurrence of other sexually transmitted infections (STIs).

RESULTS

HIV prevalence was estimated as 5.3% (4.4%-6.2%). The odds ratio (OR) of an HIV-positive recruiter choosing an HIV-positive participant was 3.9 times higher than that of an HIV-negative recruiter (P < .001). Regarding socio-demographic and sex work characteristics, low educational level, street as the main work venue, low price per sexual encounter, and longer exposure time as a sex worker were found to be associated with HIV infection, even after controlling for the homophily effect. The OR of being HIV infected among FSW who had been exposed to sexual violence at least once in a lifetime (OR = 1.5, P = .028) and the use of illicit drugs at least once a week were highly significant as well, particularly for frequent crack use (OR = 3.6, P < .001). Among the sexual behavior indicators, not using condoms in some circumstances were significantly associated with HIV infection (OR = 1.8, P = .016). Regarding the occurrence of other STI, the odds of being HIV infected was significantly higher among FSW with a reactive treponemal test for syphilis (OR = 4.6, P < .001).

CONCLUSIONS

The main factors associated with HIV infection identified in our study characterize a specific type of street-based sex work in Brazil and provided valuable information for developing interventions. However, there is a further need of addressing social and contextual factors, including illicit drug use, violence, exploitation, as well as stigma and discrimination, which can influence sexual behavior.

Changes in attitudes, risky practices, and HIV and syphilis prevalence among female sex workers in Brazil from 2009 to 2016

BACKGROUND

The present study aims at investigating the progress made toward controlling the human immunodeficiency virus (HIV)/AIDS epidemic among female sex workers (FSW) from 2009 to 2016.

METHODS

The baseline of respondent-driven sampling (RDS) study among FSW was carried out in 2009, in 10 Brazilian municipalities. In 2016, information on FSW were collected in 12 municipalities. The analyses took into account the dependence among observations, resulting from the recruitment chains, and the unequal probabilities of selection, resulting from the different network sizes. We analyzed changes in attitudes and risky behavior practices as well as variations in HIV and syphilis prevalence based on the comparison of 95% confidence intervals for each estimate.

RESULTS

Information on 2523 (2009) and 4245 (2016) FSW were analyzed. Commercial sex debut shifted to younger ages: while in 2009 the proportion of women who started sex work under 18 years old was 28.3%, in 2016 this percentage rose to 38.3%. The proportion of FSW affiliated to a nongovernmental organization (NGO) in defense of their rights (14.0%), in 2009, decreased to 7.8%, in 2016, as well as the proportion of FSW who received counseling on sexually transmitted infections (STI) in the past 6 months, from 47.5% to 24.4%. Relevant improvements were found for HIV testing in the last 12 months (from 20.3% to 39.3%). The proportions of those who were never tested for syphilis dropped from 57.9% to 48.5%. However, an opposite decreasing trend was found for the Pap smear examination in the last 12 months, decreasing from 43.6% to 31.5%. Regular condom use with clients significantly increased in the period. Regarding HIV prevalence, the 5% level was sustained and no significant differences were found, but syphilis prevalence was found to be more than 3 times higher in 2016 (8.5%) than in 2009 (2.4%).

DISCUSSION

Many are the challenges to be faced in attempting to reverse the upward trend of syphilis among FSW in Brazil. Despite the progress in condom distribution free of charge, it is necessary to increase awareness campaigns, emphasize the use, reaffirm STI counseling, and reiterate the need of regular syphilis screening in this key population group.

Percepções de mulheres profissionais do sexo sobre acesso do teste HIV: incentivos e barreiras

RESUMO Objetiva-se discutir as barreiras e os incentivos identificados pelas profissionais do sexo para a realização do teste HIV (Vírus da Imunodeficiência Humana) relacionados com a organização das ações e serviços no Sistema Único de Saúde. Pesquisa qualitativa realizada por entrevista semiestruturada na cidade de Fortaleza de 2012 a 2014. Das mulheres que fizeram o teste na atenção primária (30%), a maior parte (64%) teve acesso a ele pela assistência pré-natal. Sobre a sua realização, 17% nunca tinham feito, 69% já tinham feito alguma vez na vida e 14% realizavam-no constantemente. Foram identificadas como barreiras a falta de vagas por demanda espontânea, preconceito e falta de sigilo.

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.

HIV risk practices by female sex workers according to workplace

OBJECTIVE To investigate differences in HIV infection- related risk practices by Female Sex Workers according to workplace and the effects of homophily on estimating HIV prevalence. METHODS Data from 2,523 women, recruited using Respondent-Driven Sampling, were used for the study carried out in 10 Brazilian cities in 2008-2009. The study included female sex workers aged 18 and over. The questionnaire was completed by the subjects and included questions on characteristics of professional activity, sexual practices, use of drugs, HIV testing, and access to health services. HIV quick tests were conducted. The participants were classified in two groups according to place of work: on the street or indoor venues, like nightclubs and saunas. To compare variable distributions by place of work, we used Chi-square homogeneity tests, taking into consideration unequal selection probabilities as well as the structure of dependence between observations. We tested the effect of homophily by workplace on estimated HIV prevalence. RESULTS The highest HIV risk practices were associated with: working on the streets, lower socioeconomic status, low regular smear test coverage, higher levels of crack use and higher levels of syphilis serological scars as well as higher prevalence of HIV infection. The effect of homophily was higher among sex workers in indoor venues. However, it did not affect the estimated prevalence of HIV, even after using a post-stratification by workplace procedure. CONCLUSIONS The findings suggest that strategies should focus on extending access to, and utilization of, health services. Prevention policies should be specifically aimed at street workers. Regarding the application of Respondent-Driven Sampling, the sample should be sufficient to estimate transition probabilities, as the network develops more quickly among sex workers in indoor venues.

The validity of clinic-based samples in approximating out-of-care HIV-infected populations

Tremendous strides have been made in the diagnosis and treatment of human immunodeficiency virus (HIV); perhaps now the largest barrier to controlling HIV is retaining those diagnosed in care. Data on out-of-care populations are needed to develop effective retention methods, yet obtaining these remains methodologically challenging due to inherent difficulties in sampling. The purpose of this study was to evaluate whether individuals identified by two sampling methods commonly used to approximate out-of-care populations were significantly different from a sample of newly identified out-of-care persons. We compared medical records of 345 out-of-care persons identified by a novel population-based health information exchange who had not received CD4 or viral load monitoring in >1 year with: medical records from a randomly selected, time-matched sample of 488 HIV-infected persons with at least one HIV care visit in the past 5 years, and interviews with 382 participants from a time-matched clinic-based convenience sample. Newly identified out-of-care persons were significantly different from both proxies with respect to demographic, clinical, and utilization characteristics, suggesting that samples of in-care proxy persons are inadequate to describe those not engaged in care. Novel approaches to sampling out-of care populations are urgently needed in order to better understand these populations and ways to improve retention and slow the HIV/AIDS epidemic.

Consistently low prevalence of syphilis among female sex workers in Jinan, China: findings from two consecutive respondent driven sampling surveys

Background

Routine surveillance using convenient sampling found low prevalence of HIV and syphilis among female sex workers in China. Two consecutive surveys using respondent driven sampling were conducted in 2008 and 2009 to examine the prevalence of HIV and syphilis among female sex workers in Jinan, China.

Methods

A face-to-face interview was conducted to collect demographic, behavioral and service utilization information using a structured questionnaire. Blood samples were drawn for serological tests of HIV-1 antibody and syphilis antibody. Respondent Driven Sampling Analysis Tool was used to generate population level estimates.

Results

In 2008 and in 2009, 363 and 432 subjects were recruited and surveyed respectively. Prevalence of syphilis was 2.8% in 2008 and 2.2% in 2009, while no HIV case was found in both years. Results are comparable to those from routine sentinel surveillance system in the city. Only 60.8% subjects in 2008 and 48.3% in 2009 reported a consistent condom use with clients during the past month. Over 50% subjects had not been covered by any HIV-related services in the past year, with only 15.6% subjects in 2008 and 13.1% in 2009 ever tested for HIV.

Conclusions

Despite the low prevalence of syphilis and HIV, risk behaviors are common. Targeted interventions to promote the safe sex and utilization of existing intervention services are still needed to keep the epidemic from growing.