title: Profiles of drug users in Switzerland and effects of early-onset intensive use of alcohol, tobacco and cannabis on other illicit drug use.
abstract: OBJECTIVE
  The main aim of this study was to investigate profiles of drug users, with a particular focus on illicit drugs other than cannabis, and to explore the effect of early-onset intensive use (drunkenness, daily smoking, high on cannabis) on profiles of illicit drug use.
  
  
  METHODS
  Baseline data from a representative sample of 5,831 young Swiss men in the ongoing Cohort Study on Substance Use Risk Factors were used. Substance use (alcohol, tobacco, cannabis and 15 types of other illicit drug) and age of onset of intensive use were assessed. The Item Response Theory (IRT) and prevalence rates at different ages of onset were used to reveal different profiles of illicit drug use.
  
  
  RESULTS
  In addition to cannabis, there were two profiles of other illicit drug use: (a) "softer" drug users (uppers, hallucinogens and inhaled drugs), among which ecstasy had the highest discriminatory potential (IRT slope = 4.68, standard error (SE) = 0.48; p <0.001); and (b) "harder" drug users (heroin, ketamine, gamma-hydroxybutyrate/gamma-hydroxylactone, research chemicals, crystal meth and spice), among which ketamine had the highest discriminatory potential (slope = 4.05; SE = 0.63; p <0.001). Onset of intensive use at the age of 12 years or younger also discriminated between these two profiles.
  
  
  CONCLUSIONS
  Both the IRT model and the effect of onset of intensive use enabled two groups of illicit drugs to be identified. In particular, very early onset (at 12 years or younger) intensive use of any substance was a marker for later use of the second group of drugs.
authors.affiliation: Alcohol Treatment Centre, Lausanne University Hospital CHUV, Switzerland. stephanie.baggio@chuv.ch
authors.forename: Stéphanie
authors.initials: S
authors.lastname: Baggio
authors.forename: Joseph
authors.initials: J
authors.lastname: Studer
authors.forename: Meichun
authors.initials: M
authors.lastname: Mohler-Kuo
authors.forename: Jean-Bernard
authors.initials: JB
authors.lastname: Daeppen
authors.forename: Gerhard
authors.initials: G
authors.lastname: Gmel
mesh_terms: D017668:Age of Onset; D000428:Alcohol Drinking / Q000453:epidemiology*; D000435:Alcoholic Intoxication / Q000453:epidemiology; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D055030:Drug Users / Q000145:classification; D006801:Humans; D013287:Illicit Drugs; D008297:Male; D008385:Marijuana Smoking / Q000453:epidemiology*; D015995:Prevalence; D012307:Risk Factors; D012907:Smoking / Q000453:epidemiology*; D019966:Substance-Related Disorders / Q000453:epidemiology*; D013557:Switzerland / Q000453:epidemiology; D055815:Young Adult
chemical_list: D013287:Illicit Drugs