Purpose: The MONICA (MONItoring of trends and determinants in CArdiovascular disease) project in the region of Augsburg, Southern Germany, is the first population-based cohort study in Germany investigating the association of the risk factors hypertension, hypercholesterolemia and smoking with incident myocardial infarction and total mortality, and to assess their impact at the population level.
Methods: At baseline, 1074 men and 1013 women aged 45-64 years were randomly selected from the population in the Augsburg region and extensively interviewed and examined regarding their cardiovascular risk profile. They were traced over 13 years from 1984-1997. We calculated incidence rates, hazard rate ratios, population attributable risks (PAR), and rate advancement periods (RAP) according to the three risk factors and their combinations.
Results: Among men, 107 myocardial infarctions and 204 total mortality events occurred during the study period; in women the number of total mortality cases was 102. The three classical risk factors were associated with incident myocardial infarction in men and with total mortality in men and women over a period of 13 years. Heavily smoking men had a particularly high risk of total mortality (HRR=4.2; 95% CI 2.5-7.0) and myocardial infarction (HRR=3.8; 1.9-7.6). Men with treated hypertension were at equally high risk for both total mortality (HRR=2.4; 1.5-3.7) and myocardial infarction (HRR=2.4; 1.3-4.3). In women, treated hypertension (HRR=2.5; 1.5-4.1) and hypercholesterolemia (HRR=2.0; 1.2-3.3) were most strongly related to total mortality. Regarding the association of risk factor combinations and myocardial infarction among men, the presence of all three risk factors simultaneously (HRR=7.9; 3.6-17.3) and the combination smoking/hypercholesterolemia (HRR=5.8; 3.2-10.5) were particularly hazardous. In total, the three risk factors contributed 54% of the burden of myocardial infarction in the male study population. The rate advancement periods for myocardial infarction related to treated hypertension, hypercholesterolemia and heavy smoking were 10.5, 5.8 and 15.8 years, respectively.
Conclusions: Our results confirm the outstanding impact of the classical risk factors on myocardial infarction and total mortality in a southern German population. Coronary heart disease is largely preventable through risk factor reduction. Therefore, risk factor counselling, education and treatment are crucial to prevent people from developing the disease or dying prematurely.