Characteristics of heroin and cocaine users unknown to treatment agencies.Results from the Swiss Hidden Population Study

The aim of this study was to compare the characteristics of heroin or cocai n users who are no in contact with drug-treatment agencies in Switzerland t o the characteristics of a group who are in treatment. A sample of 917 user s of heroin and/or cocain was recruited outside treatment settings by 31 Pr ivileged Access Interviewers. Respondents were divided into a study group o f 512 heroin and/or cocain users not following any treatment, and a control group of 238 users who were following treatment. Respondents in the no-tre atment group use drugs less frequently, are less likely to inject drugs, ha ve a more social pattern of use and more often have the impression of contr olling their drug use. They have less contact with the legal system and the police, are in a better social situation and more often perceive themselve s to be in a good health. In both groups, respondents whose main drug of us e if heroin mainly cocain. There are no significant differences between the two groups regarding present HIV-risk behaviour and prevention. The data s how no significant association between the duration of use of heroin or coc ain and sings for problem use. These findings support the hypothesis that d rug users not in treatment and drug users in treatment are two distinct pop ulations, in terms of profile of drug use and prevalence of social or healt h problems that are associated to it.