Reaching hidden populations of drug users by privileged access interviewers: methodological and practical issues.

The methodological issues surrounding the use of a privileged access interviewer team to generate a network sample of drug users are examined. Traditionally network samples have tended to be used by qualitative researchers. Privileged access interviewing provides a mechanism for the application of a structured instrument to a network sampling model. In doing so some problematic issues in this area for structured methodology are overcome, reduced or standardized. The use of this method is appraised in terms of meeting the methodological requirements of the Drug Transitions study. The practical experiences of our group in using a privileged access interviewer team to interview more than 400 heroin users, many of whom were not in contact with treatment services, are discussed. This method is most appropriate for the quick collection of data, from diverse networks of drug users, by use of a structured instrument. Success is likely to be dependent on careful implementation. The ongoing monitoring of data quality is of particular importance, as is good management practice and the establishment of supportive and non exploitative relationships with the interviewer team.