Background: Studies of time trends in smoking prevalence provide a better understanding of the determinants of smoking. The present study analyses changes over time in the prevalence of smoking and heavy smoking in relation to sex, age, and education.
Methods: Data on smoking behaviour were collected by questionnaire in random samples of the general population in the area of Copenhagen. The database used included 71,842 measurements of smoking behaviour for 32,156 subjects aged 30 years or more, who had been examined at intervals between 1964 and 1994. In bi- and multivariate analyses the effects of sex, age, education, time period, and study group on the prevalence of smoking and of heavy smoking were assessed.
Results: Smoking was least prevalent in women, in the oldest age group (more than 70 years), and among those with 8 years or more of school education. During the study period (from 1964/74 to 1990/94), the prevalence of smoking decreased from 72% to 54% in men and from 52% to 46% in women. In both men and women this decrease was smallest in the least educated (less than 8 years of school education). Heavy smoking was also least prevalent in women, in the oldest age group, and among the well educated. During the study period, the unadjusted prevalence of heavy smoking decreased from 52% to 38% in men, while it increased from 17% to 21% in women. The multivariate analysis showed that the time trend for heavy smoking only depended on sex, while educational attainment and age had no impact on the trend.
Conclusion: During the last 30 years the prevalence of smoking has decreased in Denmark. The decrease has been smallest in women, and among the least educated, and the increasing trend in the prevalence of heavy smoking in women is a cause for concern.