Reproducibility of Respondent-Driven Sampling (RDS) in Repeat Surveys of Men Who have Sex with Men, Unguja, Zanzibar

Assessing Consistency of Respondent-driven Sampling Estimators by Using Repeated Surveys among People Who Inject Drugs (PWID) in New Jersey

Respondent-driven sampling (RDS) is widely used to sample populations with higher risk of HIV infection for whom no sampling frames exist. However, few studies have been done to assess the consistency of RDS estimators in real world settings. We conducted an assessment study on the consistency of RDS estimators using data from the National HIV Behavioral Surveillance - People Who Inject Drugs surveys in Newark, New Jersey from 2005 to 2018. Population parameter estimates based on RDS-I, RDS-II, Gile's SS, and HCG were compared longitudinally and cross-sectionally. Population homophily statistics and differential recruitment statistics were estimated and compared. Convergence plots were used for RDS diagnosis. Sensitivity analyses were conducted on population size estimates and seeds biases. By comparing time-insensitive population parameters and population homophily statistics estimated by four RDS estimators, the study found that RDS-II and Gile's SS could provide longitudinally and cross-sectionally consistent estimates and population homophily statistics on gender and sexual orientation. Cross-sectional comparison of time-sensitive population parameter estimates also supported the consistency of RDS-II and Gile's SS. However, RDS-I and HCG did not perform well in those comparisons. In conclusion, RDS estimators may not address all inconsistencies, but RDS-II and Gile's SS are recommended to weight RDS samples given enough consistency was observed in them.

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.

Assessing reliability of naïve respondent-driven sampling samples by using repeated surveys among people who inject drugs (PWID) in New Jersey

INTRODUCTION

Respondent-driven sampling (RDS) is widely used to sample populations with higher risk of HIV infection for whom no sampling frames exist. However, few studies have been done to assess the reliability of RDS in real world settings.

METHODS

We assessed the reliability of naïve RDS samples using five rounds of the National HIV Behavioral Surveillance - People Who Inject Drugs surveys in Newark, New Jersey from 2005 to 2018. Specifically, we compared the distributions of time-insensitive demographic characteristics in temporally adjacent RDS samples with Monte Carlo Two-Sample Kolmogorov-Smirnov Test with 100,000 replicates. The distributions of time-sensitive demographic characteristics were also compared as sensitivity analyses.

RESULTS

The study showed that repeated RDS samples among people who inject drugs in the greater Newark area, New Jersey were reliable in most of time-insensitive demographics and recruitment homophily statistics. Sensitivity analyses of time-sensitive demographics also presented consistencies in most of temporally adjacent samples.

CONCLUSIONS

In conclusion, RDS has the potential to provide reliable samples, but demographic characteristics of RDS samples may be easily biased by homophily. Future studies using RDS may need to pay more attention to potential homophily bias and consider necessary diagnostic procedures and sample adjustments.

Continuing Low Awareness and Use of Pre-exposure Prophylaxis (PrEP) for HIV among People Who Inject Drugs (PWID), San Francisco, 2022

Clinical trials provide evidence that pre-exposure prophylaxis (PrEP) prevents HIV acquisition including through sharing of injection equipment among people who inject drugs (PWID). However, uptake among many populations at risk for HIV has been slow, particularly among PWID. We examined data from the National HIV Behavioral Surveillance (NHBS) from San Francisco in 2022 to measure PrEP uptake and identify factors associated with PrEP awareness among PWID. Of 479 PWID with HIV-negative or unknown HIV status, 54.9% were aware of PrEP, 5.9% had discussed PrEP with a healthcare provider, and 1.5% had used PrEP in the past year. Lack of PrEP awareness was associated with being age 50 years and older (adjusted odds ratio [aOR] 0.40, 95% CI 0.27-0.60), being men who have sex with women (vs. men who have sex with men, aOR 0.47, 95% CI 0.24-0.92), having a disability (aOR 0.58, 95% CI 0.35-0.95), using heroin as their most frequently injected drug (aOR 0.51, 95% CI, 0.34-0.78), not having tested for HIV, HCV, or an STD in the past year (aOR 0.43, 95% CI 0.28-0.64), and not having access to new sterile needles in the past year (aOR 0.28, 95%CI 0.08-1.00). We found negligible change in the awareness and uptake of PrEP among PWID since previously measured in NHBS in 2018. Low PrEP use among PWID may be addressed by increasing provider discussion of PrEP with their PWID patients and clients during routine care, expanding testing for injection-related infections among PWID, and integrating PrEP access into harm reduction programs.

Awareness and use of HIV pre-exposure prophylaxis and factors associated with awareness among MSM in Beijing, China

Human immunodeficiency virus (HIV) sexual transmission among men who have sex with men (MSM) has increased markedly in Beijing, China in the past decade. Pre-exposure prophylaxis (PrEP) is a highly efficacious biomedical prevention strategy that remarkably reduces HIV-transmission risk. This study examined PrEP awareness among MSM and the factors influencing it. From April to July 2021, respondent-driven sampling was used to conduct a cross-sectional survey among MSM in Beijing, China. Demographic, behavior, and awareness data regarding PrEP were collected. The factors influencing PrEP awareness were assessed using univariate and multivariable logistic regression. In total, 608 eligible responders were included in the study. Among the respondents, 27.9% had PrEP awareness, 3.3% had taken PrEP, and 57.9% expressed interest in receiving PrEP, if required. Greater odds of PrEP awareness were associated with higher education level (adjusted odds ratio [aOR] 3.525, 95% confidence interval [CI] 2.013-6.173, P < 0.0001), greater HIV-related knowledge (aOR 3.605, 95% CI 2.229-5.829, P < 0.0001), HIV testing (aOR 2.647, 95% CI 1.463-4.788, P = 0.0013), and sexually transmitted infections (aOR 2.064, 95% CI 1.189-3.584, P = 0.0101). Lower odds of PrEP awareness were associated with higher stigma score (aOR 0.729, 95% CI 0.591-0.897, P = 0.0029). The findings indicate sub-optimal awareness and low utilization of PrEP in Beijing and highlight PrEP inequities among MSM with stigma. Strengthening the training of peer educators in disseminating PrEP knowledge and reducing stigma are critical for improving PrEP awareness.

HIV prevalence among men who have sex with men, transgender women and cisgender male sex workers in sub-Saharan Africa: a systematic review and meta-analysis

INTRODUCTION

Developing effective targets, policies and services for key populations requires estimations of population sizes and HIV prevalence across countries and regions. We estimated the relative and absolute HIV prevalence among men who have sex with men (MSM), transgender women and men, and male and transgender sex workers (MSW and TGSW) in sub-Saharan African countries using peer-reviewed literature.

METHODS

We performed a systematic review of peer-reviewed studies assessing HIV prevalence in MSM, transgender women and men, MSW and TGSW in sub-Saharan Africa between 2010 and 2021, following PRISMA guidelines. We searched Embase, Medline Epub, Africa Index Medicus, Africa Journal Online, Web of Science and Google Scholar. We calculated HIV prevalence ratios (PRs) between the study prevalence, and the geospatial-, sex, time and age-matched general population prevalence. We extrapolated results for MSM and transgender women to estimate HIV prevalence and the number living with HIV for each country in sub-Saharan Africa using pooled review results, and regression approximations for countries with no peer-reviewed data.

RESULTS AND DISCUSSION

We found 44 articles assessing HIV prevalence in MSM, 10 in transgender women, five in MSW and zero in transgender men and TGSW. Prevalence among MSM and transgender women was significantly higher compared to the general population: PRs of 11.3 [CI: 9.9-12.9] for MSM and 8.1 [CI: 6.9-9.6] for transgender women in Western and Central Africa, and, respectively, 1.9 [CI: 1.7-2.0] and 2.1 [CI: 1.9-2.4] in Eastern and Southern Africa. Prevalence among MSW was significantly higher in both Nigeria (PR: 12.4 [CI: 7.3-21.0]) and Kenya (PR: 8.6 [CI: 4.6-15.6]). Extrapolating our findings for MSM and transgender women resulted in an estimated HIV prevalence of 15% or higher for about 60% of all sub-Saharan African countries for MSM, and for all but two countries for transgender women.

CONCLUSIONS

HIV prevalence among MSM and transgender women throughout sub-Saharan Africa is alarmingly high. This high prevalence, coupled with the specific risks and vulnerabilities faced by these populations, highlights the urgent need for risk-group-tailored prevention and treatment interventions across the sub-continent. There is a clear gap in knowledge on HIV prevalence among transgender men, MSW and TGSW in sub-Saharan Africa.

HIV Prevalence among Injury Patients Compared to Other High-Risk Groups in Tanzania

Sixty-eight percent of persons infected with HIV live in Africa, but as few as 67% of those know their infection status. The emergency department (ED) might be a critical access point to HIV testing. This study sought to measure and compare HIV prevalence in an ED injury population with other clinical and nonclinical populations across Tanzania. Adults (≥18 years) presenting to Kilimanjaro Christian Medical Center ED with acute injury of any severity were enrolled in a trauma registry. A systematic review and meta-analysis was conducted to compare HIV prevalence in the trauma registry with other population groups. Further, 759 injury patients were enrolled in the registry; 78.6% were men and 68.2% consented to HIV counseling and testing. The HIV prevalence was 5.02% (tested), 6.25% (self-report), and 5.31% (both). The systematic review identified 79 eligible studies reporting HIV prevalence (tested) in 33 clinical and 12 nonclinical population groups. Notable groups included ED injury patients (3.53%, 95% CI), multiple injury patients (10.67%, 95% CI), and people who inject drugs (17.43%, 95% CI). These findings suggest that ED injury patients might be at higher HIV risk compared to the general population, and the ED is a potential avenue to increasing HIV testing among young adults, particularly men.

HIV testing and engagement with the HIV treatment cascade among men who have sex with men in Africa: a systematic review and meta-analysis

BACKGROUND

HIV disproportionately affects gay, bisexual, and other men who have sex with men (MSM) in Africa, where many countries criminalise same-sex behaviour. We assessed changes in the engagement of African MSM with HIV testing and treatment cascade stages over time, and the effect of anti-LGBT legislation and stigma.

METHODS

We systematically searched Embase, Global Health, MEDLINE, Scopus, and Web of Science for peer-reviewed cross-sectional or longitudinal studies recruiting at least ten MSM, published from Jan 1, 1980, to Oct 10, 2018. We extracted or derived estimates of HIV testing, engagement with the HIV treatment cascade, or both among African MSM from published reports. We derived pooled estimates using inverse-variance random-effects models. We used subgroup and meta-regression analysis to assess associations between testing and status awareness outcomes and study and participant characteristics, including the severity of country-level anti-LGBT legislation.

FINDINGS

Our searches identified 75 independent eligible studies that provided estimates for 44 993 MSM across one or more of five testing and treatment cascade outcomes. HIV testing increased significantly over time overall, with pooled proportions of MSM ever tested for HIV of 67·3% (95% CI 62·1-72·3; 44 estimates) and tested in the past 12 months of 50·1% (42·4-57·8, 31 estimates) after 2011, which were 14·8 percentage points and 17·9 percentage points higher than before 2011, respectively. After 2011, ever testing was highest in southern Africa (80·0%), and lowest in northern Africa (34·4%), with the greatest increase in western Africa (from 42·4% to 70·9%). Levels of testing ever, in the past 12 months, and status awareness were statistically significantly lower in countries with the most severe anti-LGBT legislation compared with countries with the least severe legislation (57·4% vs 71·6%, p=0·0056; 35·5% vs 49·3%, p=0·010; 6·7% vs 22·0%, p=0·0050). Few estimates were available for later stages of the treatment cascade. Available data after 2011 suggest that the pooled proportion of MSM HIV-positive aware has remained low (18·5%, 12·5-25·3; 28 estimates), whereas proportions of current antiretroviral therapy (ART) use were 23·7% (15·5-33·0; 13 estimates) among all MSM living with HIV and 60·1% (48·6-71·1; five estimates) among MSM HIV-positive aware of their status. Pooled levels of viral suppression among MSM currently on ART were 75·6% (64·4-85·5; four estimates), but only 24·7% (18·8-31·2; four estimates) among all MSM living with HIV.

INTERPRETATION

Despite improvements in HIV testing among MSM in Africa, HIV status awareness, ART coverage, and viral suppression remain much lower than required to achieve UNAIDS 90-90-90 targets. Further studies are urgently needed to provide more accurate estimates of levels of status awareness, engagement in care, ART coverage, and viral suppression among MSM to inform prevention efforts aimed at improving access to HIV services for MSM. Severe anti-LGBT legislation might be associated with lower HIV testing and status awareness; therefore, further research is needed to assess the effect of such legislation on HIV testing and engagement with the HIV treatment cascade among MSM.

FUNDING

US National Institutes of Health, UK Medical Research Council.

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.

The 12 city HIV Surveillance Survey among MSM in Brazil 2016 using respondent-driven sampling: a description of methods and RDS diagnostics

INTRODUCTION

This paper details the methods used in the second national Biological and Behavioral Surveillance Survey (BBSS) of HIV, syphilis, and hepatitis B and C among men who have sex with men in Brazil.

METHODS

Respondent-driven sampling (RDS) was used in 12 cities in 2016. The targeted sample size was initiated with five to six seeds in each city. HIV, syphilis, and Hepatitis B and C rapid tests were offered to participants. RDS Analyst with Gile's successive sampling (SS) estimator was used to adjust results as recommended and a weight for each individual was generated for further analysis. Data for the 12 cities were merged and analyzed using Stata 14.0 complex survey data tools with each city treated as its own stratum.

RESULTS

Duration of data collection varied from 5.9 to 17.6 weeks. 4,176 men were recruited in the 12 cities. Two sites failed to achieve targeted sample size due to a six-month delay in local IRB approval. No city failed to reach convergence in our major outcome variable (HIV).

CONCLUSION

The comprehensive BBSS was completed as planned and on budget. The description of methods here is more detailed than usual, due to new diagnostic tools and requirements of the new STROBE-RDS guidelines.

HIV prevalence among men who have sex with men in Brazil: results of the 2nd national survey using respondent-driven sampling

This paper reports human immuno-deficiency virus (HIV) prevalence in the 2nd National Biological and Behavioral Surveillance Survey (BBSS) among men who have sex with men (MSM) in 12 cities in Brazil using respondent-driven sampling (RDS).Following formative research, RDS was applied in 12 cities in the 5 macroregions of Brazil between June and December 2016 to recruit MSM for BBSS. The target sample size was 350 per city. Five to 6 seeds were initially selected to initiate recruitment and coupons and interviews were managed online. On-site rapid testing was used for HIV screening, and confirmed by a 2nd test. Participants were weighted using Gile estimator. Data from all 12 cities were merged and analyzed with Stata 14.0 complex survey data analysis tools in which each city was treated as its own strata. Missing data for those who did not test were imputed HIV+ if they reported testing positive before and were taking antiretroviral therapy.A total of 4176 men were recruited in the 12 cities. The average time to completion was 10.2 weeks. The longest chain length varied from 8 to 21 waves. The sample size was achieved in all but 2 cities.A total of 3958 of the 4176 respondents agreed to test for HIV (90.2%). For results without imputation, 17.5% (95%CI: 14.7-20.7) of our sample was HIV positive. With imputation, 18.4% (95%CI: 15.4-21.7) were seropositive.HIV prevalence increased beyond expectations from the results of the 2009 survey (12.1%; 95%CI: 10.0-14.5) to 18.4%; CI95%: 15.4 to 21.7 in 2016. This increase accompanies Brazil's focus on the treatment to prevention strategy, and a decrease in support for community-based organizations and community prevention programs.