Global Epidemiology

Incidence of clinical atherosclerosis
Manifestations of clinical atherosclerosis represent the major cause of death in western societies.

Cardiovascular diseases cause:

  • more than 50% of all deaths in industrialised countries;
  • 30% of care days in hospitals; and
  • 10% of early retirement.
Cardiovascular diseases due to atherosclerosis remain the leading cause of mortality in men over 45 years and in women over 65 years throughout Europe, but there are large differences in disease experience between countries and within countries over time [Wood, 1998]. The incidence of acute myocardial infarction, angina, stroke and sudden death, which represent the major manifestations of clinical atherosclerosis assessed epidemiologically, varies according to risk factors, age, gender and ethnicity at the level of both individuals and populations, and has varied markedly over time [Tyroler, 2000].

Changing patterns of incidence
In Europe in the past, the incidence of cardiovascular diseases showed a clear north-south declining gradient, but in more recent years, the gradient has moved in the west-east direction with a five-fold difference between countries. The highest mortality rates for cardiovascular diseases due to atherosclerosis are observed in Eastern Europe. In fact, for the period 1970-1992 in these countries, particularly Romania, Poland, the former East Germany and countries belonging to the former Yugoslavia, large increases in the incidence have occurred. Conversely, cardiovascular disease mortality has declined in western countries from both northern and southern European regions, such as Belgium, Finland, France and Italy [Tunstall-Pedoe, 1999].

What has caused decreases in incidence?

  • Lifestyle changes, as well as public health and medical care advances in the prevention and treatment of atherosclerosis and its clinical manifestations, have paralleled the drastic reduction of cardiovascular disease deaths, which has occurred in the USA as well as in many European countries.
  • In particular, in-hospital case fatality rates have declined, initially as a consequence of the development of coronary care units and subsequently owing to the development of medical and surgical techniques for thrombolysis and artery revascularisation.
  • Advances in diagnosis and treatment have, however, only partially contributed to the decline in cardiovascular disease mortality. In fact, improved diagnostic and therapeutic methodologies cannot prevent most of the cardiovascular disease deaths (approximately 60%), which occur outside the hospital and before any medical intervention.
A recent report from the monitoring trends and determinants in cardiovascular disease (MONICA) project suggests that in populations in which mortality decreased, coronary event rate contributed two-thirds and case fatality one-third [Tunstall-Pedoe, 1999].

What are the main determinants for the decline in mortality?
In short, despite substantial contributions from changing survival, the main determinant of the decline in cardiovascular disease mortality is the process that drives changing the rate of events, namely, lifestyle modifications. This is also confirmed by recent autopsy studies, which have disclosed geographic variation in atherosclerosis prevalence and severity associated with population mortality and close parallels between severity of atherosclerosis and prevalence of risk factors, even at young ages [Strong, 1995].

Indeed, the identification of major risk factors through population-based studies, and effective control strategies combining community education and targeted management of high-risk individuals have greatly contributed to the fall in cardiovascular disease mortality rates.

Overall trends in incidence of clinical atherosclerosis
In spite of the negative trend in cardiovascular disease mortality in western countries there has been no decrease in the absolute number of people who have experienced this disease, because of an ageing population and an improved case-to-fatality ratio. Moreover, the global burden of cardiovascular diseases has increased in recent years due to the emergence of atherosclerosis as a major health problem in the developing countries. It has been estimated that the number of deaths attributable to atherosclerosis in developing countries exceeds that observed in developed countries by 70%. An even greater cause for concern is the early age of cardiovascular disease deaths in developing countries. For example, in 1990, the proportion of cardiovascular deaths occurring below the age of 70 years was 27% in developed countries compared with 47% in developing countries [Reddy, 1998].

The increasing burden of diseases caused by atherosclerosis in developing countries is the result of three concomitant causes:

  1. The decline of infectious and nutritional disorders, which represent competing causes of death.
  2. The adverse lifestyle changes accompanying industrialisation and urbanisation.
  3. The longer periods of exposure to risk factors because of increased longevity.
Despite the present and predicted future expanding wealth of epidemiological and biomedical knowledge about the determinants of atherosclerosis, the increasing epidemic of manifestations of clinical atherosclerosis, comprising CHD, stroke and aortic and peripheral vascular diseases, presents an urgent public health challenge.



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