Effectiveness of Respondent Driven Sampling in Engaging Methamphetamine Users in HIV Prevention Research in Cape Town, South Africa

Abstract

South Africa has a substantial HIV epidemic as well as a rising methamphetamine use problem, particularly in Cape Town. Respondent driven sampling (RDS) may be a useful tool for engaging vulnerable and hard-to-reach populations in HIV research, although its effectiveness has not yet been examined among South African methamphetamine users. The aim of the current study was to describe the effectiveness of RDS as a method for engaging methamphetamine users in Cape Town into a HIV behavioral research study. RDS procedures were used to screen 374 potential participants from a peri-urban township in Cape Town. Measures of homophily, equilibrium and RDS-1 estimators were computed for key demographic and social variables. Beginning with 8 seeds, 345 methamphetamine users were enrolled over a 6 month period, with a coupon return rate of 67%. The sample included 197 men and 148 women who were ethnically diverse (73% Coloured, 27% Black African) and had a mean age of 28.8 years (SD=7.2). Social networks were adequate (mean network size >5) and mainly comprised of close social ties. Equilibrium on race was reached after 11 waves of recruitment, and after ≤3 waves for all other variables of interest. There was little to moderate preference for either in- or out-group recruiting in all subgroups.Results suggest that RDS is an effective method for engaging methamphetamine users into HIV prevention research in South Africa. RDS may be a useful strategy for seeking high risk methamphetamine users for HIV testing and linkage to HIV care in this and other low resource settings. We also discuss future directions for RDS studies.