A prognostic tool to identify adolescents at high risk of becoming daily smokers

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.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 webcite.The prognostic tool to identify youth at high risk of daily smoking may eventually be an important component of a comprehensive tobacco control system.Despite considerable declines in prevalence, cigarette smoking remains the leading avoidable threat to the health of children and adolescents. In 2006-7, nearly 50,000 Canadian youth in grades 5-9 were current smokers[1]. Further, the steady decline in the prevalence of youth smoking over the past decade has now leveled off,[2] suggesting that continued concerted effort to control cigarette smoking is needed.Cigarette smoking usually begins during early adolescence and it is now known that nicotine dependence (ND) symptoms can develop soon after first puff[3]. Withdrawal symptoms in particular present a serious obstacle to quitting and although the des