Classical risk factors and their impact on incident non-fatal and fatal myocardial infarction and all-cause mortality in southern Germany

Abstract

Background. The MONICA (Monitoring Trends and Determinants in Cardiovascular Diseases) project in Augsburg provides the first population-based cohort study in Germany to quantify the associations of the risk factors hypertension, hypercholesterolaemia and smoking with incident non-fatal and fatal myocardial infarction and all-cause mortality, and to assess their impact at the population level. Methods. The cohort comprises 1074 men and 1013 women aged 45-64 years; they were followed over 8 years from 1984-1992. In the men, there were 61 non-fatal and fatal myocardial infarctions and 92 all-cause mortality events over this period; in the women the number of deaths from all causes was 45. Incidence rates, hazard rate ratios, population attributable fractions and rate advancement periods were calculated. Results. Adjusting for confounders, the myocardial infarction hazard rate ratios for men with hypertension, or a total choleslerol/HDL-cholesterol ratio ≤ 5.5, or smoking ≤ 20 cigarettes/day, were 2.0 (95% CI 1.2-3.5), 2.9 (95% CI 1.7-5.0), and 2.7 (95% confidence interval (CI) 1.4-5.0), respectively. The risk factor combination total cholesterol/HDL cholesterol ratio ≤ 5.5 and cigarette smoking was particularly hazardous. The three risk factors contributed 65% of the burden of myocardial infarction in the population. The rate advancement period for myocardial infarction associated with hypertension, total cholesterol/HDL cholesterol ratio ≤ 5.5 or smoking ≤ 20 cigarettes/day was 8.3, 12.4 and 11.5 years, respectively. In women, these risk factors were similarly predictive of all-cause mortality. Comparing the cohort data from Augsburg with those of two occupational cohorts from Germany reveals higher absolute myocardial infarction risks in the Augsburg population; however, the relative risk estimates in the Augsburg and the two occupational cohorts were very similar. Conclusion. Our results confirm the important contribution of the classical risk factors to the risk of myocardial infarction and all-cause mortality in Germany. The results pertaining to the concept of rate advancement periods particularly demonstrate the great potential for prevention.