Using population screening for recruitment of young adults engaged in illicit drug use: methodological issues and sampling outcomes.

Social stigma, legal sanctions and the associated lack of sampling frames create barriers to the probabilistic sampling of those engaged in a variety of behaviour, including illicit drug use. We used a novel sampling approach to recruit respondents into a longitudinal study examining amphetamine-type stimulant use. A young adult population was screened for lifetime drug use to create a sampling frame of amphetamine-type stimulant users and non-users. We posted 12,118 screening questionnaires to a random selection of young adults listed on the electoral roll for Brisbane and the Gold Coast, Australia (N=107,275). Using a small pre-paid incentive and intensive telephone and postal reminders we attained a screening response rate of 49.9%. Eligible amphetamine-type stimulant users (used ecstasy or methamphetamine⩾3 times in past 12 months) and non-users (never used ecstasy or methamphetamine) were identified by screening responses. About two-thirds of each selected group took part in the longitudinal study. Comparisons with large-scale population survey data suggest the sample was broadly representative of young adult amphetamine-type stimulant users in Australia.