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Diseases of the heart and circulation - cardiovascular and cerebrovascular - such as heart attacks and stroke, kill more people than any others, accounting for over 15 million deaths, or about 30% of the global total, every year. Many more millions of people are disabled by them. Many who die are under the age of 65, and given today's increased life span, these deaths are premature. A large proportion of them are also preventable or avoidable - occurring prematurely despite a wealth of knowledge on how to reduce the risks of contracting them. They cause grief in families and are a loss of valuable talent that many countries need for economic development.
Regarded largely as lifestyle diseases because smoking, obesity, unhealthy diet and heavy alcohol consumption increase the risk of developing them, circulatory diseases were once thought of as affecting exclusively industrialized nations.
Now, as developing countries modernize, they are gradually controlling communicable diseases, and the life expectancy of their populations is increasing. Unfortunately, the risks of circulatory diseases are also increasing, partly because of the adoption of lifestyles similar to those common in industrialized countries. These diseases are emerging rapidly as a major public health concern in most developing countries, where they now account for about 25% of all deaths - 10 out of 40 million. In developed countries, almost half of all deaths - more than 5 out of 12 million - are attributable to them.
The most important circulatory diseases are hypertension, coronary heart disease, cerebrovascular disease, and cardiomyopathies. Worldwide, there are more deaths from coronary heart disease (7.2 million) than stroke (4.6 million), but more than twice as many deaths from stroke occur in developing countries as in developed countries.
In addition, the developing world still suffers from other heart conditions such as rheumatic heart disease, which is linked to poverty, and from cardiac damage related to Chagas disease, a parasitic illness afflicting about 17 million people in Latin America. About 30% of those who develop chronic Chagas disease become incapacitated because of heart damage that may also lead to sudden death. Rheumatic fever is the most common worldwide cause of heart disease in young people, accounting for about one-third of all deaths from cardiovascular diseases.
The coronary heart disease epidemic began in North America, Europe and Australasia in the early decades of this century. In many industrialized countries, death rates peaked in the 1960s and early 1970s and have since declined dramatically - by over 50% in some countries. The world's highest rates are now found in eastern and central Europe.
Decades of research have shown conclusively that a number of determinants - most of them associated with lifestyle - operating from childhood onwards, are responsible for coronary heart disease. The term "risk factor" was first used for this disease. The major risk factors are high blood pressure, cigarette-smoking, certain dietary habits (particularly excessive intake of saturated fat), elevated blood cholesterol levels, lack of physical activity, obesity and diabetes. The primary prevention of high blood pressure is crucially important in the prevention of deaths from coronary heart disease.
High blood cholesterol levels contribute to deaths more commonly among women than men. The causes can be genetic but are more usually related to a diet rich in animal fats. Lack of physical activity is the most prevalent modifiable risk factor in many industrialized countries.
Rheumatic fever/rheumatic heart disease is the most common cardiovascular disease in children and young adults, currently affecting at least 12 million people, and causing 400 000 deaths a year. More than 2 million require repeated hospital admissions and 1 million will need heart surgery in the next 5-20 years.
Stroke and other cerebrovascular diseases are the second most common worldwide cause of death, accounting for more than 4.6 million deaths worldwide, of which two-thirds are in developing countries. Mortality and morbidity occur mainly in the over-65 age group. High blood pressure is the most common risk factor; others are those mentioned for coronary heart disease. About one-third of stroke patients die within six months of the event; most of these deaths occur in the first month. Survivors may be severely disabled.
Hypertension is the most common cardiovascular disorder, affecting about 20% of the adult population. It is considered both as a disease category and as one of the major risk factors for heart disease, stroke and kidney disease. It is particularly common in elderly men and women. The major risk factors are overweight, poor dietary habits, particularly excessive intake of salt and alcohol and inadequate physical activity. Several genetic factors may also play a role.