Instability in smoking patterns among school leavers in Victoria, Australia

Objective-To describe patterns of smoking in a cohort of young adults over the first 15 months after leaving school. Design-A four-wave, longitudinal survey design was used to gather data. Final-year students from 93 schools completed the recruitment questionnaire at an average age of 17 years. Follow-up questionnaires were posted to their home addresses three months, nine months and 15 months after the end of school. Setting-Victoria, Australia. Participants-A cohort of 1903 respondents who completed and returned all four questionnaires. Main outcome measures-Self-labelled smoking status ("heavy smoker","light Smoker", "occasional smoker", "ex-smoker", ana "non-smoker"), daily cigarette consumption, and maximum daily cigarette consumption. Results-At school, 72% of the sample were "non-smokers", 5% "ex-smokers", 11% "Occasional", 8% "Light", and 5% "heavy smokers". At 15 months after school, these proportions had shifted to 64%, 8%, 11%, 9%, and 7%, respectively. Over the study, "light smokers" and "heavy smokers" substantially increased their daily consumption; "occasional" and "ex-smokers" did not. There was relatively high stability in self-labelled smoking status at one wave and the next. However, over the four waves, 38% of the sample changed their self-labelled smoking status, and 41% of these had been "non-smokers" at school. A reduced second-order Markov chain model was found to fit this four-wave behavioural sequence. Detailed description of smoking status changes revealed greater progression to higher levels of smoking than transition to lower levels. Conclusions-There is considerable flux in smoking patterns among young adults after leaving school, suggesting an opportunity to intervene with smoking prevention programmes at this stage of development.