Background: Our aim was to study how combinations of three unhealthy behaviors (smoking, physical inactivity, and use of dairy fat) and an index describing their number were associated with the risk of cardiovascular mortality in a society showing remarkable improvement in health behaviors.
Methods: The material consisted of random samples of annual adult health behavior surveys from 1978 to 1991; included were 8,869 men and 10,105 women ages 45 to 64 years. The mortality follow-up covered Years 1978 to 1993. The study period was divided into four phases on the basis of number of deaths and timing of health behavior changes. Poisson multivariate models were used to determine the risk of cardiovascular mortality by all combinations of unhealthy behaviors and the index. In the models age, education, chronic morbidity, and body mass index were adjusted for.
Results: Each unhealthy behavior was found to be a risk factor for cardiovascular mortality when the whole study period was examined. Among men, daily smoking was a significant predictor of cardiovascular mortality in the first three phases, among women in the first and third phase. Among men physical inactivity became significant only in the last phase, among women in all except the last phase. The combinations of physical inactivity with use of dairy fat or with smoking were more significant for women than for men. The combination of smoking and use of dairy fat was significant only for men. The association of the index with cardiovascular mortality was slightly stronger among women than among men.
Conclusions: The predictive values of unhealthy behaviors on cardiovascular mortality changed by period depending on their frequency. The combinations of unhealthy behaviors are to be preferred over the index in description of lifestyle determinants of cardiovascular mortality.