The importance of timing of transitions for risk of regular smoking and nicotine dependence

Background Estimating the timing and speed among smoking milestones is an important challenge for epidemiology given that further reductions in smoking prevalence may be best achieved by programs that target potentially malleable smoking behavior before the development of nicotine dependence. Purpose The purpose of the study was to investigate the association between the timing and speed of transition among major smoking milestones (onset, weekly, and daily smoking) and onset and recovery from nicotine dependence. Methods Analyses are based on data from The National Comorbidity Survey-Replication, a nationally representative face-to-face household survey conducted between February 2001 and April 2003. Results Of those who had ever smoked (n=5,692), 71.3% had reached weekly smoking levels and 67.5% had reached daily smoking. Four in ten who had ever smoked met criteria for nicotine dependence. A shorter time since the onset of weekly and daily smoking was associated with a transition to both daily smoking and nicotine dependence, respectively. The risk for each smoking transition was highest within the year following the onset of the preceding milestone. Recovery was associated with a longer period of time between smoking initiation and the development of dependence and a later age of smoking onset. Conclusions These findings shed light on the clinical course of smoking and nicotine dependence. Given the importance of timing of smoking transitions, prevalence may be further reduced through intervention targeted at adolescents and young adults in the months most proximal to smoking initiation.