Role of known risk factors in explaining the difference in the risk of coronary heart disease between eastern and southwestern Finland.

We analysed to what extent cardiovascular risk factors may explain the observed difference in the risk of coronary heart disease (CHD) between two areas with markedly different CHD incidence. The study included 7049 men aged 25-64 years who had participated in a baseline survey in 1982 or in 1987 in the Kuopio and North Karelia provinces of eastern Finland and in the Turku-Loimaa region of southwestern Finland. During the baseline surveys the following factors were determined: smoking, blood pressure, cholesterol, high-density lipoprotein cholesterol, diabetes, height, body mass index, family history of CHD and socioeconomic status. The cohorts were followed for coronary events until the end of 1994. CHD risk was about 40% higher in eastern than in southwestern Finland. The levels of most of the measured risk factors were also higher in eastern Finland. Differences in risk factor levels explained about 40% of the excess CHD risk in eastern Finland. The impact of the classical risk factors, such as smoking, cholesterol and blood pressure, on the regional difference was smaller than expected. Single risk factor measurements in our population surveys, however, may not have correctly reflected the long-term exposure of individuals to these risk factors, particularly because the surveys were carried out within a period during which these risk factors were undergoing favourable changes in the Finnish population. In addition to the classical risk factors, regional differences in body height and socioeconomic status were associated with the regional differences in CHD risk.