title: Smoking trajectories of adolescent novice smokers in a longitudinal study of tobacco use.
abstract: OBJECTIVE
  To describe longitudinal trajectories of smoking intensity in adolescent novice smokers and to identify predictors of trajectory class membership.
  
  
  METHODS
  Cigarette consumption among 369 novice smokers (mean age 13 years) was measured over a mean 24 months of follow-up after smoking onset. Classes of smoking intensity trajectories were identified using latent class growth modeling. Predictors of trajectory class membership were identified in polytomous logistic regression.
  
  
  RESULTS
  There was considerable between-subject heterogeneity in individual trajectories over time. Four classes of smoking intensity trajectories were identified: low-intensity, non-progressing smokers (72.4% of subjects), and slow, moderate, and rapid escalators (11.1%, 10.8%, and 5.7% of subjects, respectively). Gender, poor academic performance, and having more than half of friends who smoke at smoking onset independently predicted development of trajectory pattern. Escalating trajectory patterns were associated with earlier development of nicotine dependence and tolerance.
  
  
  CONCLUSIONS
  Cigarette consumption will not escalate rapidly among three-quarters of adolescent novice smokers. Novice smokers who do escalate rapidly should be targeted for early tobacco control intervention to prevent development of nicotine dependence and sustained smoking.
authors.affiliation: Department of Epidemiology and Biostatistics, Faculty of Medicine, McGill University, Montréal, Québec H3G 1A4, Canada. igor.karp@mail.mcgill.ca
authors.forename: Igor
authors.initials: I
authors.lastname: Karp
authors.forename: Jennifer
authors.initials: J
authors.lastname: O'Loughlin
authors.forename: Gilles
authors.initials: G
authors.lastname: Paradis
authors.forename: James
authors.initials: J
authors.lastname: Hanley
authors.forename: Joseph
authors.initials: J
authors.lastname: Difranza
mesh_terms: D000293:Adolescent; D000294:Adolescent Behavior; D016739:Behavior, Addictive; D015331:Cohort Studies; D005260:Female; D006801:Humans; D016014:Linear Models; D008137:Longitudinal Studies; D008297:Male; D011792:Quebec / Q000453:epidemiology; D012307:Risk Factors; D012907:Smoking / Q000453:epidemiology* / Q000639:trends; D011795:Surveys and Questionnaires; D014029:Tobacco Use Disorder; D014026:Nicotiana