title: A prognostic tool to identify adolescents at high risk of becoming daily smokers.
abstract: BACKGROUND
  The American Academy of Pediatrics advocates that pediatricians should be involved in tobacco counseling and has developed guidelines for counseling. We present a prognostic tool for use by health care practitioners in both clinical and non-clinical settings, to identify adolescents at risk of becoming daily smokers.
  
  
  METHODS
  Data were drawn from the Nicotine Dependence in Teens (NDIT) Study, a prospective investigation of 1293 adolescents, initially aged 12-13 years, recruited in 10 secondary schools in Montreal, Canada in 1999. Questionnaires were administered every three months for five years. The prognostic tool was developed using estimated coefficients from multivariable logistic models. Model overfitting was corrected using bootstrap cross-validation. Goodness-of-fit and predictive ability of the models were assessed by R2, the c-statistic, and the Hosmer-Lemeshow test.
  
  
  RESULTS
  The 1-year and 2-year probability of initiating daily smoking was a joint function of seven individual characteristics: age; ever smoked; ever felt like you needed a cigarette; parent(s) smoke; sibling(s) smoke; friend(s) smoke; and ever drank alcohol. The models were characterized by reasonably good fit and predictive ability. They were transformed into user-friendly tables such that the risk of daily smoking can be easily computed by summing points for responses to each item. The prognostic tool is also available on-line at http://episerve.chumontreal.qc.ca/calculation_risk/daily-risk/daily_smokingadd.php.
  
  
  CONCLUSIONS
  The prognostic tool to identify youth at high risk of daily smoking may eventually be an important component of a comprehensive tobacco control system.
authors.affiliation: University of Montréal Hospital Research Centre (CRCHUM), Montreal, Quebec, Canada. igor.karp.1@umontreal.ca
authors.forename: Igor
authors.initials: I
authors.lastname: Karp
authors.forename: Gilles
authors.initials: G
authors.lastname: Paradis
authors.forename: Marie
authors.initials: M
authors.lastname: Lambert
authors.forename: Erika
authors.initials: E
authors.lastname: Dugas
authors.forename: Jennifer
authors.initials: J
authors.lastname: O'Loughlin
mesh_terms: D000293:Adolescent; D000294:Adolescent Behavior; D000428:Alcohol Drinking / Q000453:epidemiology; D002170:Canada / Q000453:epidemiology; D002648:Child; D005260:Female; D033062:Friends; D006801:Humans; D008297:Male; D015999:Multivariate Analysis; D010290:Parents; D011379:Prognosis; D011446:Prospective Studies; D018570:Risk Assessment / Q000379:methods*; D012907:Smoking / Q000453:epidemiology*; D011795:Surveys and Questionnaires