What makes a respondent-driven sampling "seed" productive? Example of finding at-risk Massachusetts men who have sex with men

Respondent-Driven Sampling for Estimation of the Cumulative Lifetime Incidence of Abortion in Soweto, Johannesburg, South Africa: A Methodological Assessment

Respondent-driven sampling (RDS) is a potential strategy for addressing challenges in accurate estimation of abortion incidence, but it relies on often untested assumptions. We conducted an RDS study to estimate the cumulative lifetime incidence of abortion in Soweto, Johannesburg, South Africa (April-December 2018), to evaluate whether RDS assumptions were met, and to compare RDS estimates of incidence with estimates adjusted for employment and age based on census data. A total of 849 participants were recruited from 11 seed participants between April and December 2018. The assumption that individuals can identify target population members and the assumption of approximation of sampling with replacement was met. There were minor violations of the assumptions of seed independence from the final sample and reciprocity of ties. Assumptions of accurate degree reporting and random recruitment were not met. Failure to meet assumptions yielded a study sample with different employment characteristics than those of the target population; this could not be resolved by standard RDS methods. The RDS estimate of cumulative lifetime abortion incidence was 12.1% (95% confidence interval: 9.8, 14.3), and the employment-adjusted estimate was 16.9% (95% confidence interval: 12.8, 22.1). We caution researchers in using RDS for representative estimates of abortion incidence. Use of postsurvey weights to adjust for differences in characteristics between the sample and the target population may yield more representative results.

Incidence of and Experiences with Abortion Attempts in Soweto, South Africa: Respondent-Driven Sampling Study

BACKGROUND

Estimation of abortion incidence, particularly in settings where most abortions occur outside of health facility settings, is critical for understanding information gaps and service delivery needs in different settings. However, the existing methods for measuring out-of-facility abortion incidence are plagued with methodological challenges. Respondent-driven sampling (RDS) may offer a methodological improvement in the estimation of abortion incidence.

OBJECTIVE

In this study, we tested the feasibility of using RDS to recruit participants into a study about abortion and estimated the proportion of people who ever attempted abortion as well as 1-year and 5-year incidence of abortion (both in-facility and out-of-facility settings) among women of reproductive age in Soweto, South Africa.

METHODS

Participants were eligible if they identified as a woman; were aged between 15 and 49 years; spoke English, Tswana, isiZulu, Sotho, or Xhosa; and lived in Soweto. Working with community partners, we identified 11 seeds who were provided with coupons to refer eligible peers to the study. Upon arrival at the study site, the recruits completed an interviewer-administered questionnaire that solicited information about demographic characteristics, social network composition, health behaviors, sexual history, pregnancy history, and experience with abortion; recruits also received 3 recruitment coupons. Recruitment was tracked using coupon numbering. We used the RDS-II estimator to estimate the population proportions of demographic characteristics and our primary outcome, the proportion of people who ever attempted abortion.

RESULTS

Between April 4, 2018, and December 17, 2018, 849 eligible participants were recruited into the study. The estimated proportion of people who ever attempted abortion was 12.1% (95% CI 9.7%-14.4%). A total of 7.1% (95% CI 5.4%-8.9%) reported a facility-based abortion, and 4.4% (95% CI 3.0%-5.8%) reported an out-of-facility abortion.

CONCLUSIONS

The estimated proportion of people who ever attempted abortion of 12% (102/849) in our study likely represents a substantial underestimation of the actual proportion of abortion attempts among this study population-representing a failure of the RDS method to generate more reliable estimates of abortion incidence in our study. We caution against the use of RDS to measure the incidence of abortion because of persistent concerns with underreporting but consider potential alternative applications of RDS with respect to the study of abortion.

Challenges of virtual RDS for recruitment of sexual minority women for a behavioral health study

Respondent driven sampling (RDS) is an approach commonly used to recruit nonprobability samples of rare and hard-to-find populations. The purpose of this study was to explore the utility of phone and web-based RDS methodology to sample sexual minority women (SMW) for participation in a telephone survey. Key features included 1) utilizing a national probability survey sample to select seeds; 2) web-based recruitment with emailed coupons; and 3) virtual processes for orienting, screening and scheduling potential participants for computer-assisted telephone interviews. Rather than resulting in a large diverse sample of SMW, only a small group of randomly selected women completed the survey and agreed to recruit their peers, and very few women recruited even one participant. Only seeds from the most recent of two waves of the probability study generated new SMW recruits. Three RDS attempts to recruit SMW over several years and findings from brief qualitative interviews revealed four key challenges to successful phone and web-based RDS with this population. First, population-based sampling precludes sampling based on participant characteristics that are often used in RDS. Second, methods that distance prospective participants from the research team may impede development of relationships, investment in the study, and motivation to participate. Third, recruitment for telephone surveys may be impeded by multiple burdens on seeds and recruits (e.g., survey length, understanding the study and RDS process). Finally, many seeds from a population-based sample may be needed, which is not generally feasible when working with a limited pool of potential seeds. This method may yield short recruitment chains, which would not meet key RDS assumptions for approximation of a probability sample. In conclusion, potential challenges to using RDS in studies with SMW, particularly those using virtual approaches, should be considered.

The Co-Evolution of Network Structure and PrEP Adoption among a Large Cohort of PrEP Peer Leaders: Implications for Intervention Evaluation and Community Capacity-Building

Background: Peer leader interventions are effective strategies for promoting prevention behaviors in communities at risk for HIV, yet little is known about their effects on the social and behavioral dynamics of peer leaders themselves. Methods: Using data from PrEP Chicago, an RCT PrEP for prevention intervention for young Black MSM (YBMSM), we apply stochastic actor-based models to longitudinally model the impact of study participation on the online friendship and PrEP adoption dynamics among a network of peer leaders (n = 174) and a network of control group counterparts (n = 166). Results: Peer leaders assigned to the same leadership training workshop were more likely to form new Facebook friendships with one another, whereas control participants assigned to the same attention control workshop were no more or less likely to form new friendships. Further, peer leaders with greater PrEP intentions and those living with HIV were more active in forming new friendships with other peer leaders, effects not found in the control network. PrEP adoption was not influenced by network dynamics in either group. Conclusions: The implications of these findings are discussed through the lens of community-capacity building and the role that peer leader interventions and the networks they engage can impact public health.

Improving HIV Self-Testing Social Network Interventions: The Role of Sexual Behavior Disclosure Among Chinese Men Who Have Sex with Men

We assessed if same-sex sexual behavior disclosure of index men who have sex with men (MSM) was related to number of HIV self-testing (HIVST) kits requested by index participants, and number of test results successfully uploaded by alters in a network-based HIVST intervention. Index participants are men who accessed and distributed HIVST kits and alters are index's social contacts who received kits. We analyzed treatment arm data [N = 106, mean age = 27 (SD = 5.3)] of an intervention conducted among MSM in Guangzhou, China, May 2019-December 2019. Index MSM who disclosed sexual behavior to their family tended to request more kits [adjusted incidence rate ratio (aIRR) 1.42, 95% CI 1.06, 1.90, p < .05]. Index men who disclosed sexual behavior to their family (aIRR 2.47, 95% CI 1.17, 5.24, p < .05) tended to yield an increase in number of alter test results uploaded. Findings have implications for the development of network-based interventions for key populations.

Individual and Social Network Structure Characteristics Associated with Peer Change Agent Engagement and Impact in a PrEP Intervention

Interventions that utilize the influence of peer change agents (PCAs) have been shown to be effective strategies for engaging key populations in HIV prevention. To date, little is known about the characteristics of PCAs associated with their effectiveness. Drawing on data from a peer leader PrEP intervention for young Black men who have sex with men (YBMSM) (N = 423), we evaluated the effects of experiential (i.e., living with HIV, PrEP awareness, PrEP use), psychographic (i.e., self-perceived leadership, innovativeness), and network (i.e., degree centrality, eigenvector centrality, and brokerage) characteristics on three effectiveness outcomes: (1) recruiting peers into the study; (2) completing "booster" sessions; and (3) linking peers to PrEP care. For each outcome, multivariable regressions were performed. On average, PCAs recruited 0.89 peers, completed 1.99 boosters, and had 1.33 network peers linked to PrEP care. Experiential factors: Prior PrEP awareness was positively associated with booster completion. Network factors: Being a network broker (i.e., connecting otherwise disconnected communities) was positively associated with peer recruitment but negatively associated with linking peers to PrEP, and degree centrality (i.e., the number of network connections someone has) and eigenvector centrality (i.e., being connected to well-connected network associates) were positively associated with linking peers to PrEP. Psychographic characteristics were not associated with any outcome. These findings can be used to inform PCA selection and to identify subpopulations who require additional support to excel as PCAs.

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

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

Statistical adjustment of network degree in respondent-driven sampling estimators: venue attendance as a proxy for network size among young MSM

We introduce a new venue-informed network degree measure, which we applied to respondent-driven sampling (RDS) estimators. Using data collected from 746 young MSM in 2014-2016 in Chicago, IL, and Houston, TX, we estimated the population seroprevalence of HIV and syphilis and risk/protective behaviors, using RDS estimates with self-reported network size as a standard degree measure as well as our proposed venue-informed degree measure. The results indicate that the venue-informed degree measure tended to be more efficient (smaller variance) and less biased than the other measure in both cities sampled. Venue attendance-adjusted network size may provide a more reliable and accurate degree measure for RDS estimates of the outcomes of interest.

Multiple strategies to identify HIV-positive black men who have sex with men and transgender women in New York City: a cross-sectional analysis of recruitment results

INTRODUCTION

Black men who have sex with men and transgender women are at high risk for HIV infection, but are more likely to be unaware of their infection or not in care for diagnosed HIV compared to other races. Respondent driven sampling has been advanced as a method to reach stigmatized and hidden populations for HIV testing. We compared strategies to recruit black, substance-using men who have sex with men and transgender women to identify newly diagnosed HIV infection, or those previously diagnosed but not in care.

METHODS

The STAR (Seek, Test, and Retain) study (ClinicalTrials.gov NCT01790360) used several recruitment strategies to identify black, substance-using men who have sex with men and transgender women with undiagnosed HIV infection or with previously diagnosed HIV infection but who were not in HIV care. Respondent-driven sampling, community-based recruitment and online advertising were used to recruit participants. Incentivized peer referral was integrated into all recruitment strategies. Participants completed interviewer-administered questionnaires and HIV testing. Demographic and HIV risk-related characteristics and recruitment strategy were summarized and stratified by HIV status. Associations were tested using Pearson's chi-squared, Fisher's exact, and Wilcoxon rank sum tests. Factors associated with HIV-positive diagnosis at p < 0.1 were included in a multivariable logistic regression model.

RESULTS

From July 2012 through October 2015, the study enrolled 1929 participants; 96.3% men who have sex with men and 3.7% transgender women. Behavioural risk factors included recent condomless anal sex (55.6%) and recent substance use during sex (73.1%). HIV prevalence was 8.7%. In multivariable analysis, significant associations with HIV infection included being transgender; non-Hispanic black; gay/homosexual orientation; not homeless; and less likely to have insufficient income for necessities. Among recruitment strategies, respondent driven sampling was least effective in identifying HIV-positive participants.

CONCLUSIONS

Integrating multiple recruitment strategies yielded a large sample of black men who have sex with men and transgender women at substantial risk for HIV. Respondent-driven sampling was less effective than other strategies at identifying men who have sex with men and transgender women with HIV.

Health Care Discrimination, Sex Behavior Disclosure, and Awareness of Pre-Exposure Prophylaxis Among Black Men Who Have Sex With Men

Background

Perceived healthcare-related discrimination and disclosure of same-sex sex behaviors to healthcare providers may act as barriers to awareness of pre-exposure prophylaxis (PrEP) for Black/African-American men who have sex with men (BMSM). Given the elevated rates of HIV transmission among young BMSM in particular, age is likely an important factor for determining the correlates of PrEP awareness unique to BMSM of different ages.

Method

147 BMSM (M age = 30.6 years, SD = 10.3 years) located in the Southeastern United States were recruited from gay-identified bars, clubs, bathhouses, parks, and street locations, via online classifieds (e.g., Craigslist) and social media (e.g., Facebook). Participants completed surveys that included questions about demographic characteristics, perceived healthcare-related discrimination, disclosure of same-sex sex behavior to healthcare providers, and PrEP awareness.

Results

Perceived healthcare-related discrimination was significantly, negatively associated with PrEP awareness, and same-sex sex behavior disclosure to healthcare providers was significantly, positively related to awareness of PrEP among BMSM. A moderation analysis, with participant age as the moderator, revealed that higher perceived healthcare-related discrimination was significantly, negatively associated with PrEP awareness beginning at 30.2 years of age, and that the relationship strengthened as age increased.

Discussion

Perceived healthcare-related discrimination plays a particularly important role in PrEP awareness for BMSM who are 30 years of age and older. Discrimination in healthcare settings may impact BMSM's ability, particularly those who are older, to access PrEP information. Healthcare professionals must establish procedures for identifying appropriate patients for PrEP, and prioritize addressing the psychosocial factors that impede PrEP awareness for their BMSM patients.

Social venue range and referral chain impact: Implications for the sampling of hidden communities

Background

It has been argued that the success of respondent-driven sampling (RDS) in generating unbiased estimates for epidemiologic outcomes depends on participants’ abilities to generate long referral chains. While this is thought to depend on the number of people participants know in the target population, this idea is rarely tested. Furthermore, little attention has been paid to the role of other aspects of social connectedness in recruitment, such as participants’ involvement in local clubs and venues.

Methods

We examine whether the recruitment potential of young Black men who have sex with men (YBMSM) depends on (1) their social network size and (2) their affiliations with a variety of sex venues across geographic areas. We analyze data from a 2014 RDS study of 598 YBMSM on the south side of Chicago.

Results

Both a participant’s personal network size and the number of different types of sex venues with which he was affiliated were significantly positively associated with (1) the total number of recruits in the participant’s prospective referral chains and (2) the lengths of those chains. However, only venue affiliation remain significantly associated with recruitment potential in the multivariate model.

Conclusions

The success of RDS in generating valid samples may depend more on recruiting participants who are involved in multiple venues within the community (i.e., their affiliation networks) than on recruiting those who have large personal social networks.

Using Respondent Driven Sampling to Identify Malaria Risks and Occupational Networks among Migrant Workers in Ranong, Thailand

Background

Ranong Province in southern Thailand is one of the primary entry points for migrants entering Thailand from Myanmar, and borders Kawthaung Township in Myanmar where artemisinin resistance in malaria parasites has been detected. Areas of high population movement could increase the risk of spread of artemisinin resistance in this region and beyond.

Methods

A respondent-driven sampling (RDS) methodology was used to compare migrant populations coming from Myanmar in urban (Site 1) vs. rural (Site 2) settings in Ranong, Thailand. The RDS methodology collected information on knowledge, attitudes, and practices for malaria, travel and occupational histories, as well as social network size and structure. Individuals enrolled were screened for malaria by microscopy, Real Time-PCR, and serology.

Results

A total of 619 participants were recruited in Ranong City and 623 participants in Kraburi, a rural sub-district. By PCR, a total of 14 (1.1%) samples were positive (2 P. falciparum in Site 1; 10 P. vivax, 1 Pf, and 1 P. malariae in Site 2). PCR analysis demonstrated an overall weighted prevalence of 0.5% (95% CI, 0–1.3%) in the urban site and 1.0% (95% CI, 0.5–1.7%) in the rural site for all parasite species. PCR positivity did not correlate with serological positivity; however, as expected there was a strong association between antibody prevalence and both age and exposure. Access to long-lasting insecticidal treated nets remains low despite relatively high reported traditional net use among these populations.

Conclusions

The low malaria prevalence, relatively smaller networks among migrants in rural settings, and limited frequency of travel to and from other areas of malaria transmission in Myanmar, suggest that the risk for the spread of artemisinin resistance from this area may be limited in these networks currently but may have implications for regional malaria elimination efforts.

Factors Associated with Productive Recruiting in a Respondent-Driven Sample of Men who Have Sex with Men in Vancouver, Canada

Respondent-driven sampling (RDS) has become a preferred sampling strategy for HIV research and surveillance in many global settings. Methodological investigation into the validity of RDS-generated samples has helped improve theoretical components of design. However, the operational challenges of implementing RDS remain underreported. We sought to identify factors independently associated with productive recruiting in an urban RDS-generated sample of gay, bisexual, and other men who have sex with men (MSM). Data were collected from the Momentum Health Study, a cohort of MSM recruited by RDS in Vancouver, Canada. Eligible men were given up to six RDS coupons to recruit their peers. The primary outcome was a count variable of each participant's number of eligible recruits. Multivariable Poisson regression identified independent predictors of productive recruitment. In total, 719 individuals comprised this analysis, of which 119 were seeds. The distribution of eligible recruits was right skewed, with 391 (54.4 %) having never recruited another participant and only eight participants (1.1 %) having recruited five. Significant, independent predictors of recruiting one additional participant included network size per ten unit increase (adjusted risk ratio [aRR] 1.03), being of Aboriginal race/ethnicity compared with White (aRR 1.51), being HIV-positive (aRR 1.31), being sexually active with only males (aRR 2.48), being single compared with common law/married (aRR 1.37), having recently read gay newspapers (aRR 1.58), having recently sought sex partners online (aRR 1.33) and being out to a male parent (aRR 1.30). This analysis demonstrates the importance of social network size in RDS adjustment, but also identifies other socio-demographic and behavioral variables that increased RDS coupon return, which may help researchers better operationalize the implementation of RDS.

Including Online-Recruited Seeds: A Respondent-Driven Sample of Men Who Have Sex With Men

Background

Technology has changed the way men who have sex with men (MSM) seek sex and socialize, which may impact the implementation of respondent-driven sampling (RDS) among this population. Initial participants (also known as seeds) are a critical consideration in RDS because they begin the recruitment chains. However, little information is available on how the online-recruited seeds may effect RDS implementation.

Objective

The objectives of this study were to compare (1) online-recruited versus offline-recruited seeds and (2) subsequent recruitment chains of online-recruited versus offline-recruited seeds.

Methods

Between 2012 and 2014, we recruited MSM using RDS in Vancouver, Canada. RDS weights were used with logistic regression to address each objective.

Results

A total of 119 seeds were used, 85 of whom were online-recruited seeds, to recruit an additional 600 MSM. Compared with offline-recruited seeds, online-recruited seeds were less likely to be HIV-positive (OR 0.34, 95% CI 0.13-0.88), to have attended a gay community group (AOR 0.33, 95% CI 0.12-0.90), and to feel gay community involvement was “very important” (AOR 0.16, 95% CI 0.03-0.93). Online-recruited seeds were more likely to ask a sexual partner’s HIV status always versus <50% of the time (AOR 5.21, 95% CI 1.17-23.23), to have watched the Pride parade (AOR 6.30, 95% CI 1.69-23.45), and to have sought sex online (AOR 4.29, 95% CI 1.53-12-12.05). Further, compared with recruitment chains started by offline-recruited seeds, recruits from chains started by online-recruited seeds (283/600, 47.2%) were less likely to be HIV-positive (AOR 0.25, 95% CI 0.16-0.40), to report “versatile” versus “bottom” sexual position preference (AOR 0.56, 95% CI 0.35-0.88), and to be in a relationship lasting >1 year (AOR 1.65, 95% CI 1.06-2.56). Recruits of online seeds were more likely to be out as gay for longer (eg, 11-21 vs 1-4 years, AOR 2.22, 95% CI 1.27-3.88) and have fewer Facebook friends (eg, 201-500 vs >500, AOR 1.69, 95% CI 1.02-2.80).

Conclusions

Online-recruited seeds were more prevalent, recruited fewer participants, but were different from those recruited offline. This may therefore help create a more diverse overall sample. Our work has shown the value of geosocial networking apps for aiding RDS recruitment efforts, especially when faced with slow participation uptake by other means. Understanding the degree to which networks interact will be an important next step in confirming the efficacy of online RDS recruitment strategies.

A Comparison of Referred Sexual Partners to Their Community Recruited Counterparts in The BROTHERS Project (HPTN 061)

The BROTHERS Project (HPTN 061) was established to determine the feasibility and acceptability of a multi-component intervention among African American MSM to reduce HIV incidence. The goal of this analysis was to determine if the sexual partner referral approach used in HPTN 061 broadened the reach of recruitment with regards to characteristics associated with higher infection rates and barriers to quality health care. Overall, referred sexual partners had notable structural barrier differences in comparison to community-recruited participants: lower income, less education, higher unemployment, HIV positive diagnosis, incarceration history, and no health insurance. The study's findings pose implications for utilizing the sexual partner referral approach in reaching African American MSM who may not be accessed by traditional recruitment methods or who are well-integrated in health care systems.

Respondent-driven sampling among gay and bisexual men: experiences from a New Zealand pilot study

Background

Respondent-driven sampling (RDS) is a method of approximating random sampling of populations that are difficult to locate and engage in research such as gay, bisexual and other men who have sex with men (GBM). However, its effectiveness among established urban gay communities in high-income countries is largely unexplored outside North America. We conducted a pilot study of RDS among urban GBM in Auckland, New Zealand to assess its local applicability for sexual health research.

Findings

Pre-fieldwork formative assessment explored RDS suitability among local GBM. Highly-networked initial participants (“seeds”) and subsequent participants completed a questionnaire, took a rectal swab for chlamydia and gonorrhoea testing, and were asked to recruit up to three eligible peers over the subsequent 2 weeks using study coupons. Compensation was given for participating and for each peer enrolled. Feedback on the pilot was obtained through questionnaire items, participant follow-up, and a focus group. Nine seeds commenced recruitment, directly enrolling 10 participants (Wave One), who in turn enrolled a further three (Wave Two). Two of the 22 participants (9 %) had undiagnosed rectal chlamydia. The coupon redemption rate (23 %) was lower than the expected rate (33 %) for this population. Participants were motivated by altruism above financial incentives; however, time, transport and reluctance recruiting peers were perceived as barriers to enrolment.

Discussion

Slow recruitment in our pilot study suggests that RDS might not be an effective or efficient method of sampling gay men in all high-income urban settings. However those who participated in the pilot were willing to provide anal swabs and information on their sexual behaviour, and also on the size of their GBM social network which is necessary to weight data in RDS. Refinements and adaptations such as reducing the transaction costs of taking part (e.g. offering online participation) could improve responses but these have their own drawbacks (higher set-up costs, difficulty collecting biological specimens).

Evaluation of respondent-driven sampling in a study of urban young men who have sex with men

Evidence suggests that respondent-driven sampling (RDS) is an efficient approach to sampling among varied populations of adult men who have sex with men (MSM) both in the USA and abroad, although no studies have yet evaluated its performance among younger MSM, a population with a steep rise in HIV infection in recent years. Young MSM (YMSM) may differ in terms of their connectedness to other YMSM (e.g., due to evolving sexual identity, internalization of sexual minority stigma, and lack of disclosure to others) and mobility (e.g., due to parental monitoring) which may inhibit the sampling process. The aims of this study were to evaluate the efficiency and effectiveness of RDS-based sampling among young urban MSM and to identify factors associated with recruitment success. We hypothesized that demographic, social, behavioral, and network factors, including racial/ethnic minority status, homelessness (i.e., as an indicator of socioeconomic marginalization), HIV-positive status, substance use problems, gay community connectedness, and network size would be positively related to recruitment productivity, while sexual minority stigmatization, environmental barriers (e.g., parental monitoring), and meeting sex partners on the internet (i.e., virtual venue) would be negatively related to recruitment productivity. Between December 2009 and February 2013, we used RDS to recruit a sample of 450 YMSM, ages 16-20. Findings suggest that the use of RDS for sampling among YMSM is challenging and may not be feasible based on the slow pace of recruitment and low recruitment productivity. A large number of seeds (38 % of the sample, n = 172) had to be added to the sample to maintain a reasonable pace of recruitment, which makes use of the sample for RDS-based population estimates questionable. In addition, the prevalence of short recruitment chains and segmentation in patterns of recruitment by race/ethnicity further hamper the network recruitment process. Thus, RDS was not particularly efficient in terms of the rate of recruitment or effective in generating a representative sample. Hypotheses regarding factors associated with recruitment success were supported for network size and internalized stigma (but not other factors), suggesting that participants with larger network sizes or high levels of internalized stigma may have more and less success recruiting others, respectively.

Sampling methodologies for epidemiologic surveillance of men who have sex with men and transgender women in Latin America: an empiric comparison of convenience sampling, time space sampling, and respondent driven sampling

Alternatives to convenience sampling (CS) are needed for HIV/STI surveillance of most-at-risk populations in Latin America. We compared CS, time space sampling (TSS), and respondent driven sampling (RDS) for recruitment of men who have sex with men (MSM) and transgender women (TW) in Lima, Peru. During concurrent 60-day periods from June-August, 2011, we recruited MSM/TW for epidemiologic surveillance using CS, TSS, and RDS. A total of 748 participants were recruited through CS, 233 through TSS, and 127 through RDS. The TSS sample included the largest proportion of TW (30.7 %) and the lowest percentage of subjects who had previously participated in HIV/STI research (14.9 %). The prevalence of newly diagnosed HIV infection, according to participants' self-reported previous HIV diagnosis, was highest among TSS recruits (17.9 %) compared with RDS (12.6 %) and CS (10.2 %). TSS identified diverse populations of MSM/TW with higher prevalences of HIV/STIs not accessed by other methods.

Comparison of sampling methods for hard-to-reach francophone populations: yield and adequacy of advertisement and respondent-driven sampling

BACKGROUND

Francophones who live outside the primarily French-speaking province of Quebec, Canada, risk being excluded from research by lack of a sampling frame. We examined the adequacy of random sampling, advertising, and respondent-driven sampling for recruitment of francophones for survey research.

METHODS

We recruited francophones residing in the city of Calgary, Alberta, through advertising and respondentdriven sampling. These 2 samples were then compared with a random subsample of Calgary francophones derived from the 2006 Canadian Community Health Survey (CCHS). We assessed the effectiveness of advertising and respondent-driven sampling in relation to the CCHS sample by comparing demographic characteristics and selected items from the CCHS (specifically self-reported general health status, perceived weight, and having a family doctor).

RESULTS

We recruited 120 francophones through advertising and 145 through respondent-driven sampling; the random sample from the CCHS consisted of 259 records. The samples derived from advertising and respondentdriven sampling differed from the CCHS in terms of age (mean ages 41.0, 37.6, and 42.5 years, respectively), sex (proportion of males 26.1%, 40.6%, and 56.6%, respectively), education (college or higher 86.7% , 77.9% , and 59.1%, respectively), place of birth (immigrants accounting for 45.8%, 55.2%, and 3.7%, respectively), and not having a regular medical doctor (16.7%, 34.5%, and 16.6%, respectively). Differences were not tested statistically because of limitations on the analysis of CCHS data imposed by Statistics Canada.

INTERPRETATION

The samples generated exclusively through advertising and respondent-driven sampling were not representative of the gold standard sample from the CCHS. Use of such biased samples for research studies could generate misleading results.

Mutual HIV disclosure among HIV-negative men who have sex with men in Beijing, China, 2010

HIV is rising rapidly among Chinese men who have sex with men (MSM). Discussion of HIV status between sexual partners is potentially a key prevention behavior. It is unclear if HIV-negative Chinese MSM talk about HIV and disclose their HIV status with sexual partners. Understanding the correlates of disclosure among this population could provide insight into developing disclosure-based interventions. We conducted a respondent driven sampling based study of 500 MSM in Beijing. A total of 332 men had a previous HIV-negative test result and thus considered themselves to be HIV-negative and were included in our analysis of disclosure. Equal numbers of these men reported talking about HIV and disclosing their HIV status to at least one sexual partner. MSM who disclosed were more likely to be living with a main partner. No other demographic characteristics were associated with disclosure in bivariate analysis. We also used data on up to three sexual partners per participant to examine disclosure on the partnership level. Main partnerships, meeting partners at bars/clubs, sometimes using alcohol before sex in a partnership, and usually having sex at home compared to other venues were associated with disclosure. Using generalized estimating equation analysis to characterize individuals from their partnership data, we found only having at least one main partnership and knowing people who were infected with HIV to be associated with a participant being a discloser. Interventions that wish to harness discussion of HIV and HIV status among Chinese MSM will need to focus on moving these discussions towards having them with casual partners.

Reducing alcohol-related harm in disadvantaged men: development and feasibility assessment of a brief intervention delivered by mobile telephone

Background

Socially disadvantaged men suffer substantial harm from heavy drinking. Brief alcohol interventions are effective in reducing consumption when delivered via health care. There is a need for tailored brief interventions for disadvantaged men who seldom attend health care.

Objectives

(1) To investigate the best ways to recruit and retain disadvantaged men in a study aimed at reducing the frequency of heavy drinking. (2) To identify the type of content and timing of the delivery that is most likely to engage disadvantaged young to middle-aged men in an intervention delivered by text messages. (3) To determine whether or not the intervention is likely to be an acceptable way to influence the frequency of heavy drinking.

Design

A three-phase study involving the development of the recruitment strategy and the intervention, an assessment of the feasibility of a randomised controlled trial, and a post-study evaluation.

Setting

Community-based study, conducted in Dundee, UK.

Participants

Disadvantaged men aged 25–44 years who had two or more episodes of heavy drinking (≥ 8 units in a single session) in the preceding month. Two recruitment strategies were employed: recruitment through general practice (GP) registers and recruitment through a community outreach strategy.

Interventions

Focus groups explored drinking motives and behaviours of the target group. The intervention also drew on reviews of the literature on: alcohol brief interventions, text message studies, communication theory and behaviour change theories and techniques. The intervention group received 36 text messages with images sent over a 28-day period.

Main outcome measures

The outcome measures evaluated the likely success of a full trial: recruitment of the participants; construction and delivery of a theoretically and empirically based intervention that successfully engages disadvantaged men; potential for the intervention to influence binge drinking.

Results

The focus group analyses identified that personal experience and knowledge of the harmful effects of alcohol was widespread. Furthermore, there was a discrepancy between frequent binge drinking and perceived social expectations and duties. This could usefully be targeted in the intervention. Theoretically and empirically based behaviour change strategies were successfully rendered in attractive, colourful, brief text messages. Both recruitment strategies (GP registers and community outreach) proved successful and a total of 67 men were recruited, exceeding the target of 60. The participants were at high risk of harm because of frequent episodes of heavy binge drinking. Baseline interviews established that those recruited through community outreach drank substantially more and had more frequent binge drinking sessions than those recruited through GP registers. Retention at follow-up was 96%. Extensive process evaluation was conducted. The evaluation showed that 95% of text messages were successfully delivered to participants' telephones. Furthermore, there was a high level of engagement with text messages which sought responses. Most men replied to these texts, often giving carefully structured personal responses. Analyses of the responses indicated a high level of engagement with key components of the behaviour change strategy. Post-trial evaluation showed high levels of satisfaction with the intervention.

Conclusions

This study has shown that disadvantaged men can be recruited and retained in an alcohol intervention trial. A theoretically and empirically based intervention was successfully delivered by text message. Furthermore, the messages were well received and elicited the types of response intended. A full trial of the intervention, incorporating a cost-effectiveness study, should be carried out.

Study registration

This study is registered as ISRCTN10515845.

Funding

The National Institute for Health Research Public Health Research programme.

Risky single-occasion drinking and disadvantaged men: will recruitment through primary care miss hazardous drinkers?

BACKGROUND

Men who are socially disadvantaged are at a substantially higher risk of developing alcohol-related diseases. People from deprived areas are known to be more difficult to recruit to research studies. As part of a feasibility assessment for an intervention study, 2 recruitment strategies were investigated. This article compares the drinking patterns of the disadvantaged men identified by the 2 strategies.

METHODS

A cross-sectional survey compared 2 strategies for recruiting disadvantaged men to a study on alcohol consumption: recruitment through general practice (GP) registers and through a community outreach strategy, respondent-driven sampling (RDS). Men aged 25 to 44 years were recruited from deprived areas in the community. The entry criterion was binge drinking (≥8 units in a single session) at least twice in the previous 4 weeks. Demographic characteristics, total consumption of alcohol, frequency of binge drinking (≥8 units in a session), and heavy binge drinking (≥16 units in a session) were measured.

RESULTS

Men recruited by RDS drank more than twice as much as the men recruited through GP (137 units in the previous 30 days compared with 62 units; p = 0.003). They also had many more binge drinking days: more than half (57%) of men from RDS had 6 or more binge drinking days in the previous 30 days, whereas only 16% of the GP sample had 6 or more binge drinking days (p = 0.001). Many more men recruited by RDS (37% vs. 5%; p = 0.002) had more than 5 very heavy drinking sessions in the previous month (≥16 units in a session). The RDS group also had fewer alcohol-free days.

CONCLUSIONS

The 2 sampling strategies recruited different types of drinkers. The men recruited through RDS were much more likely to engage in frequent harmful drinking. The results indicate that the 2 methods recruit different samples of disadvantaged men. Intervention studies that are only conducted through primary care may miss many harmful drinkers.

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

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

Cannabis Dependence and Peer Selection in Social Networks of Frequent Users

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