, Volume 83, Issue 1 Supplement, pp 39-53,
Open Access This content is freely available online to anyone, anywhere at any time.
Date: 10 Nov 2006

Methods to Recruit Hard-to-Reach Groups: Comparing Two Chain Referral Sampling Methods of Recruiting Injecting Drug Users Across Nine Studies in Russia and Estonia


Evidence suggests rapid diffusion of injecting drug use and associated outbreaks of HIV among injecting drug users (IDUs) in the Russian Federation and Eastern Europe. There remains a need for research among non-treatment and community-recruited samples of IDUs to better estimate the dynamics of HIV transmission and to improve treatment and health services access. We compare two sampling methodologies “respondent-driven sampling” (RDS) and chain referral sampling using “indigenous field workers” (IFS) to investigate the relative effectiveness of RDS to reach more marginal and hard-to-reach groups and perhaps to include those with the riskiest behaviour around HIV transmission. We evaluate the relative efficiency of RDS to recruit a lower cost sample in comparison to IFS. We also provide a theoretical comparison of the two approaches. We draw upon nine community-recruited surveys of IDUs undertaken in the Russian Federation and Estonia between 2001 and 2005 that used either IFS or RDS. Sampling effects on the demographic composition and injecting risk behaviours of the samples generated are compared using multivariate analysis. Our findings suggest that RDS does not appear to recruit more marginalised sections of the IDU community nor those engaging in riskier injecting behaviours in comparison with IFS. RDS appears to have practical advantages over IFS in the implementation of fieldwork in terms of greater recruitment efficiency and safety of field workers, but at a greater cost. Further research is needed to assess how the practicalities of implementing RDS in the field compromises the requirements mandated by the theoretical guidelines of RDS for adjusting the sample estimates to obtain estimates of the wider IDU population.

Platt, Rhodes, Hickman, and Bobrova are with the Centre for Research on Drugs and Health Behaviour, Department of Public Health and Policy, London School of Hygeine and Tropical Medicine, London, UK; Wall and Renton are with the Institute for Health and Human Development, University of East London, London, UK; Judd is an independent consultant with the Medical Research Council Clinical Trials Unit, London, UK; Hickman is with the Department of Social Medicine, University of Bristol, Bristol, UK; Johnston is an independent consultant with Institute for Global Health, University of California, San Francisco, CA, USA; Sarang is an independent consultant with the Central and Eastern European Harm Reduction Network, Vilnius, Lithuania.