How to find non-dependent opiate users: a comparison of sampling methods in a field study of opium and heroin users

The first aim is to better understand the potentials and limitations of different sampling methods for reaching a specific, rarely studied population of drug users and for persuading them to take part in a multidisciplinary study. The second is to determine the extent to which these different methods reach similar or dissimilar segments of the non-dependent opiate-using population.

Using ethnographic fieldwork (EFW) and targeted canvassing (TARC; small newspaper advertisements and website announcements), supplemented by snowball referrals, we recruited and interviewed 127 non-dependent opiate users (lifetime prevalence of use 5-100 times; 86.6% had used heroin and 56.7% opium). Average age was 39.0; 66.1% were male and 33.9% female.

In addition to opiates, many respondents had wide experience with other illicit drugs. The majority had non-conventional lifestyles. Both EFW and TARC yielded only limited numbers of snowball referrals. EFW requires specific skills, is labour-intensive, thus expensive, but allows unsuitable candidates to be excluded faster. Respondents recruited through EFW were significantly more likely to have experience with opium and various drugs other than opiates. TARC resulted in larger percentages of women and respondents with conventional lifestyles. TARC is less labour-intensive but requires more time for screening candidates; its cost-effectiveness depends on the price of advertising for the recruitment.

Different methods reach different segments of the population of non-dependent opiate users. It is useful to employ a multi-method approach to reduce selectivity.