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Member Research & Reports

Member Research & Reports

Taiwan Researchers Apply Respondent-Driven Sampling to Derive Epidemiological Estimates of Illegal Drug Use

A social network method called respondent-driven sampling (RDS) can be applied in recruiting regular tobacco and alcohol users to estimate illegal drug use prevalence, according to a study by researchers at National Taiwan University (NTU) and other institutes. This study has been published online since August 1 in Journal of Epidemiology.

Conducted by Dr. Te-Tien Ting, a former doctoral student at NTU and currently a postdoctoral fellow at University of George, and her advisors Drs. Wei J. Chen & Chuan-Yu Chen, the study is aimed to evaluate the practical utility of RDS among regular tobacco and alcohol users in Taipei, Taiwan, where the stigma attached to illegal drug use runs high and illegal drug users are considered as criminals by law.

“The RDS utilizes probability-theoretical methods to compensate for nonrandom sampling and produces proper estimates to monitor risk-taking behaviors. Nevertheless, participants’ preference and contextual constraints related differential recruitment in the RDS recruiting process would introduce bias in the chain-referral sampling,” said Dr. Ting, the first author of the article.

RDS was implemented from 2007 to 2010 to recruit seed individuals who were 18 to 50 years old, regular tobacco and alcohol users, and currently residing in Taipei. Each respondent was asked to refer up to five friends known to be regular tobacco smokers and alcohol drinkers to participate in the present study. Information pertaining to drug use was collected using an audio computer-assisted self-interview instrument.

They found that the prevalence estimates of illegal-drug-using behaviors attained equilibrium after three to five recruitment waves. Nearly one-fifth of the participants had ever used illegal drugs, of whom over 60 percent were polydrug users. The RDS-adjusted prevalences of illegal drug using behaviors among early-onset smokers were all twice or three times higher than those among late-onset smokers

“Our results provided an empirical basis for the practical utility of RDS to obtain reliable epidemiologic estimates of illegal drug use in the population characterized with regular use of tobacco and alcohol,” the authors write. Furthermore, as Dr. WJ Chen notes, “Among this population, those who initiated tobacco smoking before age 18 were more likely to use illegal drugs and be polydrug users. In response to these rapid changes in technology and social behavior, network-based sampling (e.g., RDS) and computer assisted interview might make it easier to approach diverse participants and recruit drug cohorts compared with other modes of sampling methods (e.g., random sampling).”