Development of smoking by birth cohort in the adult population in eastern Finland 1972-97.

OBJECTIVE To analyse the dynamics of smoking prevalence, initiation, and cessation in relation to sex, age, birth cohort, study year, and educational level. DESIGN Six independent cross-sectional population surveys repeated every five years between 1972 and 1997. SETTING The provinces of North Karelia and Kuopio in eastern Finland. SUBJECTS Independent random samples of 18,088 men and 19,200 women aged 25-64 years. Those comprising the oldest birth cohort were born in 1913-17 and those in the youngest were born in 1968-72. RESULTS Among men the prevalence of smoking decreased over time, but the cohort effect observed in smoking initiation was obscured by the changes in smoking cessation. Differences between the educational categories were small. Among women the prevalence of smoking increased during the study period. This was mainly caused by the less highly educated, in whom smoking initiation clearly increased in successive birth cohorts, but a more moderate cohort effect was also present among the more highly educated women. CONCLUSIONS In men decreased initiation and increased cessation contributed to the downward trend in smoking prevalence, whereas among women, changes in smoking were mostly caused by augmented initiation in successive birth cohorts. During the study period educational inequalities in smoking widened, as the less highly educated came increasingly to form the smoking population.