Using respondent-driven sampling to recruit psychoactive drug users: experiences from a pilot study conducted in Kandy District Sri Lanka

Abstract

Psychoactive drug users are considered a hidden population and sampling community-based drug users are not feasible with probability sampling methods. The aim of the study was to conduct a pilot study to assess the feasibility of the Respondent Driven Sampling method to sample psychoactive drug users in the community. A community-based pilot study was conducted in Kandy District among 180 psychoactive drug users recruited using Respondent Driven Sampling. Formative assessment was conducted before data collection. Six purposely selected seeds were used. An incentive was provided for every respondent. RDS Analyst free software version 0.64 was used to visualize recruitment trees, recruitment waves, conduct recruitment homophily, convergence analysis, frequency distributions of sociodemographic characteristics and drug use patterns. Seven waves were reached to recruit the 180 drug users in five weeks duration. Two of the six seeds were unproductive. The coupon redeem rate was 34%. Hoping to quit drug use was the main reason for participating in the study. Eighty-one per cent found the data collection site easy or somewhat easy to access. The required sample size was able to achieve with respondent-driven sampling within a short duration of time while fulfilling basic assumptions of respondent-driven sampling. Moreover, the data demonstrate recruiting participants across genders, ethnicities, income levels, occupations, as well as drug use patterns. Therefore, it is a feasible and successful method to recruit psychoactive drug users in the community.