[20 years of cardiovascular epidemiology. The epidemiologist's viewpoint]

Abstract

The author reviews the evolution of cardiovascular epidemiology during the twenty last years. The mortality from cardiovascular diseases with atherosclerosis as their pathological basis grew rapidly in the industrialised countries after World War II. This led to epidemiological research which started in 1950 with respectively the studies of Framingham in the United States and the Seven Countries Study, essentially in Europe. The concept of multifactorial origin of coronary heart disease was proposed during the 60s. Three major coronary risk factors besides age and gender, hypercholesterolemia, hypertension and cigarette smoking emerged systematically in epidemiological studies before 1975. The last twenty years have confirmed the importance of these three modifiable coronary risk factors which are long-term predictors in different ethnic groups, both in males and females. Other risk factors appeared in this period. Some polymorphisms of several genes as well as their phenotypic expression have been found to be related to an increased risk of coronary heart disease. Uni- and multifactorial primary and secondary prevention trials have confirmed the observations of analytical epidemiology. Moreover, the crucial role of nutrition within a metabolic hypothesis has been confirmed by experimental research. The concept of the strategy of prevention in higher risk subjects as well as in the whole population was proposed by international bodies following the publications by the English epidemiologist G. Rose. Both France and Belgium contributed to the development of cardiovascular epidemiology during the last twenty years. France is doing cutting-edge research on genetic predictors of cardiovascular diseases. Although the multifactorial causal model of cardiovascular diseases is robust, it is still a probabilistic one; it predicts however relative risks of about 15 to 1 according to the decile of the multilogistic function distribution. Environmental factors essentially related to lifestyles explain a great part of these differences. At the individual level, genetic factors most probably modulate these environmental influences and one can foresee in the future a more predictive model. In most medical schools, teaching of cardiovascular epidemiology and prevention has a low priority with clinicians putting the accent on the risk factors rather than on the risk profile of the individual. Secondary prevention is more in the realm of clinical medicine due to a large publicity given to the results of the large randomised trials. Consequently, in hospital mortality of acute myocardial infarction is decreasing as well as long-term mortality. Finally, prevention at the population level is connected to political decisions in public health which could have a major impact on the economy at the country level. Consequently, these political decisions are very slow to be taken both at the national and European Union level.