ECOLOGICAL ANALYSIS OF THE ASSOCIATION BETWEEN MORTALITY AND MAJOR RISK-FACTORS OF CARDIOVASCULAR-DISEASE

Background. The WHO Multinational Monitoring of Trends and Determinants in Cardiovascular Disease (MONICA) Project has been established to measure trends in cardiovascular mortality and coronary heart disease and cerebrovascular disease morbidity and to assess the extent to which these trends are related to changes in known risk factors at the same time in defined communities in different countries. This cross-sectional study is based on data from the early part of the Project and assesses the association between mortality and population risk factor levels. Methods. Thirty-five populations of men and women aged 35-64 years are used in correlation analyses between four mortality measures (deaths from all causes, cardiovascular diseases, ischaemic heart disease and stroke) and three cardiovascular risk factors (regular cigarette smoking, blood pressure and total cholesterol). Results. In male populations all-causes mortality and stroke mortality had more than 39% of their variance explained by the three risk factors but all cardiovascular and ischaemic heart disease mortality had less than 25% of their variance explained. For female populations each mortality measure except ischaemic heart disease mortality had more than 33% of their variances accounted for by the three risk factors. For both the male and female populations each of the mortality measures shows strong associations with high blood pressure but the associations with smoking and high cholesterol are generally weaker and much less consistent. Conclusions. This analysis has shown that accepted cardiovascular mortality risk factors measured cross-sectionally at the population level do not reflect well the variation in mortality between populations.