title: The characteristics of 'new users' of cocaine and heroin unknown to treatment agencies: results from the Swiss Hidden Population Study.
abstract: OBJECTIVE
  To examine the characteristics of 'new users' (i.e. first use not more than 5 years before interview) of heroin or cocaine currently unknown to treatment agencies in Switzerland, compared to 'new users' who are in treatment, as well as to 'experienced users' (i.e. first use more than 5 years before interview).
  
  
  METHODS
  A sample of 917 users of heroin and/or cocaine users were recruited outside treatment settings by 31 privileged access interviewers and interviewed face to face using a standardized questionnaire. The study group was composed of 95 'new users' of heroin and/or cocaine who had never been in treatment. It was compared to four control groups: control group 1 (n = 48) consisting of 'new users' known to treatment agencies; control group 2 (n = 443) of 'experienced users' who reported having never had any contact with treatment agencies; control group 3 (n = 53) of 'experienced users' with some history of treatment but not in contact at the time of interview; and control group 4 (n = 166) of 'experienced users' in contact with treatment agencies.
  
  
  RESULTS
  Compared with 'new' and 'experienced' users in treatment (control groups 1 and 4), 'new users' unknown to treatment agencies have a less problematic profile of drug use: they inject less, use drugs less frequently, more often report the impression of controlling their drug use, have fewer health problems and fewer social difficulties. However, compared to experienced users not in contact with treatment agencies (control groups 2 and 3), the profile of drug use in the study group is more problematic. Injection-related HIV-risk behaviour is lower in the study group than in all the control groups. The analysis showed no influence of duration of drug use, gender or education over getting in touch with treatment agencies in the first five years of drug use.
  
  
  CONCLUSIONS
  Some of the 'new users' unknown to treatment agencies can be considered as being in need of assistance. Efforts to enhance the treatment on offer should be continued. Drug users should be provided with better knowledge of how to identify signs for problem drug use and need for assistance.
authors.affiliation: Institut de recherche sur l'environnement construit, Swiss Federal Institute of Technology, Lausanne, Switzerland. Daniel.Kuebler@epfi.ch
authors.forename: D
authors.initials: D
authors.lastname: Kuebler
authors.forename: D
authors.initials: D
authors.lastname: Hausser
authors.forename: J P
authors.initials: JP
authors.lastname: Gervasoni
mesh_terms: D000328:Adult; D000367:Age Factors; D017668:Age of Onset; D000704:Analysis of Variance; D019970:Cocaine-Related Disorders / Q000523:psychology* / Q000628:therapy; D004522:Educational Status; D005260:Female; D006304:Health Status; D006556:Heroin Dependence / Q000523:psychology* / Q000628:therapy; D006703:Ill-Housed Persons / Q000523:psychology; D006801:Humans; D008297:Male; D010342:Patient Acceptance of Health Care; D012737:Sex Factors; D012924:Social Conditions; D013557:Switzerland / Q000453:epidemiology; D013997:Time Factors