The incidence of mortality from cardiovascular disease (CVD) has decreased substantially in western societies since the World Health Organization (WHO) initiated the MONICA (multinational MONItoring of trends and determinants in CArdiovascular disease) project in the early 1980s. From the results of this project, it was concluded that decreases in the classical risk factors – smoking, cholesterol and blood pressure – explain a great part of the decline in coronary heart disease (CHD) . In addition, changes in coronary care and secondary prevention contributed substantially to lower CHD mortality [2, 3]. Recent modelling of trends in Sweden and Finland showed that 55–60% of the reduction in CHD deaths was due to improved risk-factor patterns, particularly lower cholesterol levels [4, 5]. The importance of the classical risk factors is further corroborated by results from the INTERHEART study .
The role of general obesity as a risk factor is unclear, and abdominal obesity may be a better predictor of myocardial infarction . Obesity has been linked to increased cardiovascular mortality , but because of the close relation with other established risk factors, it has not been included in commonly used risk predictors, such as the Framingham risk score. Socioeconomic inequalities in CHD mortality  are partly due to higher risk-factor levels in subjects with a low socioeconomic position . Increased mortality from ischaemic heart disease (IHD) has been reported among people with low income in Scotland , and a low level of education was the most consistent socioeconomic predictor in the INTERHEART study, with highest impact in high-income countries .
Modelling of the impact of risk factors is hampered by the lack of valid data from representative populations using strict and uniform methodology for assessing risk-factor levels over long time periods. Published studies suffer from short-time frames , comparisons between different populations or areas [5, 13, 14] and restriction of analyses by age groups and gender ; in addition, there is a lack of recent data [16–18]. The most comprehensive data come from the US NHANES study . European data are scarce with the exception of a recent Finnish report .
In the Northern Sweden MONICA Study, we have repeated population surveys and maintained registries of myocardial infarction and stroke despite the termination of the WHO collaboration in 1995. Since 1985, mortality from IHD has decreased by 69% in men and 45% in women , and in nondiabetic subjects, the mortality from stroke has decreased by 4% per year . Here, we present data on time trends in major cardiovascular risk factors from six population surveys over 23 years.