title: Social gradient in initiation and transition to daily use of tobacco and cannabis during adolescence: a retrospective cohort study.
abstract: OBJECTIVE
  This study explores whether the family socio-economic status (F-SES) and school situation could have an impact on tobacco and cannabis initiation and transition to daily use during adolescence.
  
  
  METHODS
  A French cross-sectional nation-wide survey conducted in 2005 containing retrospective data.
  
  
  METHODS
  French teenagers aged 17 (n = 29 393).
  
  
  METHODS
  The F-SES was defined by the highest occupational category of either parent, with seven categories ranging from unemployed/inactive to managers/professionals. Ages at repeat school years, at leaving school, at the first episode of drunkenness and at initiation of illicit drug use were used to model tobacco and cannabis initiation and transition to daily use with time-discrete logistic regressions.
  
  
  RESULTS
  The risk for tobacco initiation was almost equally distributed across F-SES groups, but the risk of a progression to daily use was higher in every F-SES category compared to managers/professionals [odds ratio (OR) from 1.17 to 1.90]. Compared to managers/professionals, risk of cannabis initiation was lower in all F-SES categories (OR from 0.63 to 0.87), but all categories except farmers were at increased risk of transition to daily use: the OR range between 1.29 (intermediate) and 1.98 (unemployed/inactive). Repeating school years and leaving school predicted daily use of tobacco (OR = 2.00 and 2.37) and cannabis (4.58 and 2.07).
  
  
  CONCLUSIONS
  Adolescents from the highest family socio-economic status categories are at risk for tobacco and cannabis experimentation but are less prone to engage in daily use. Psychological and social mechanisms that inhibit transition to daily use should be investigated, including school attainment and performance.
authors.affiliation: Institut National des Études Démographiques (INED), Paris, France. stephane.legleye@ined.fr
authors.forename: Stéphane
authors.initials: S
authors.lastname: Legleye
authors.forename: Eric
authors.initials: E
authors.lastname: Janssen
authors.forename: François
authors.initials: F
authors.lastname: Beck
authors.forename: Nearkasen
authors.initials: N
authors.lastname: Chau
authors.forename: Myriam
authors.initials: M
authors.lastname: Khlat
mesh_terms: D000293:Adolescent; D000294:Adolescent Behavior; D000367:Age Factors; D004522:Educational Status; D004812:Epidemiologic Methods; D005260:Female; D005602:France / Q000453:epidemiology; D006801:Humans; D008297:Male; D008385:Marijuana Smoking / Q000453:epidemiology* / Q000523:psychology; D009790:Occupations; D010379:Peer Group; D012189:Retrospective Studies; D012907:Smoking / Q000453:epidemiology* / Q000523:psychology; D012923:Social Class; D012959:Socioeconomic Factors; D013332:Student Dropouts