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

Ludlam et al. BMC Res Notes (2015) 8:549 DOI 10.1186/s13104-015-1449-5 Open Access PROJECT NOTE Respondent‑driven sampling among gay and bisexual men: experiences from a New Zealand pilot study Adrian H. Ludlam1,2, Peter J. W. Saxton1,2*, Nigel P. Dickson2 and Jeffery Adams3 Abstract 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). Keywords: Respondent-driven sampling, Gay and bisexual men, Sexually transmitted infections, HIV, Probability sample, Pilot study, Feasibility study, Formative assessment, New Zealand Background Respondent-driven sampling (RDS) is a method that is purported to approximate a random sample in populations that are difficult to locate and engage in research. It is a form of chain-referral sampling in which participants are also each asked to recruit a limited number of *Correspondence: 2 AIDS Epidemiology Group, Department of Preventive and Social Medicine, University of Otago, Dunedin, New Zealand Full list of author information is available at the end of the article eligible peers. Importantly, RDS methods provide a way of overcoming biases inherent in chain-referral sampling, and therefore of approximating probability data, so long as recruitment protocols are followed, and participants’ data account for homophily and are inversely weighted based on peer network size [1, 2]. Because participation in RDS studies typically requires presentation to a physical study location, it also enables both biological specimens and behavioural data to be collected. Thus RDS has high potential for investigating HIV and sexually © 2015 Ludlam et al. This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/ publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated. Ludlam et al. BMC Res Notes (2015) 8:549 transmitted infection (STI) prevalence among groups such as gay, bisexual and other men who have sex with men (GBM) who are disproportionately affected. In spite of the strong theory on which RDS is based, there is limited evidence that it has actually been a valuable method to research GBM across a range of settings. Anecdotally several attempts have been unsuccessful or have violated key assumptions [3]. Unusually, few RDS studies have been reported in high-income countries with established GBM communities in Western Europe or Australasia [4, 5], with the majority of successful studies undertaken in lower/middle income countries [6] or in North America [7–10]. This is despite the potential of RDS to provide superior estimates than the more commonly used gay community convenience sampling. Furthermore, Western European and Australasian countries generally have tolerant socio-legal environments towards homosexuality which should make RDS fieldwork comparatively simpler. Research examining the viability of RDS in these settings is needed. New Zealand has an existing programme of non-random, purposive, community-based and web-based HIV behavioural surveillance among GBM [11], which has been used to collect oral fluid specimens [12]. However, collection of more comprehensive and invasive biological specimens for estimating STI prevalence among the GBM population, such as rectal specimens, is less feasible using these programmes. A quasi-probability sample derived through RDS, in which participants were willing to attend a centre and provide such specimens, would therefore be valuable. The aim of this study was to conduct a pilot of RDS among urban GBM in Auckland, New Zealand, to assess whether this would be a suitable method of studying the prevalence of a range of STIs in this population. Methods Formative assessment The pilot study was designed by adapting the methods of Johnston [13]. It was conducted in Auckland, a sprawling multicultural city of 1.4 million people. Auckland has the largest GBM population in New Zealand that is geographically clustered in the inner city [14]. Public and civic celebration of gay, bisexual, lesbian and transgender communities is common. A 2011 convenience-based study of GBM estimated HIV prevalence to be 6.5 % which was greater than among GBM living elsewhere in New Zealand [12]. Formative assessment with the community-based New Zealand AIDS Foundation (NZAF) sought feedback on the proposed method. NZAF also provided characteristics of social and sexual networks of GBM, and identified highly-networked initial participants (“seeds”). This Page 2 of 5 consultation suggested that much of the GBM population in Auckland was networked through partially (...truncated)