Heart diseases and blood vessel diseases are together known as cardiovascular disease. There are of various types. The leading cardiovascular diseases are coronary heart disease, also known as ischemic heart disease, which is because of blockages in the blood vessels of the heart, ultimately resulting in heart attacks and damage to the heart muscle and sudden cardiac deaths in some instances. Cerebral vascular disease is also called stroke or brain attack. Some of the earlier manifestations of coronary heart disease and stroke are called angina or transient ischemic attack. Also you have peripheral vascular disease which is disease of the blood vessels elsewhere in the body. Now these, the coronary heart disease, stroke and peripheral vascular disease are all united by common risk factors, which cause these blood vessel blockages and the subsequent damages in the brain or in the heart. And these risk factors are high blood pressure, high blood fats, also called dyslipidemia, diabetes and its precursor impaired glucose tolerance, smoking, both active and passive, physical inactivity and there are several other risk factors also implicated, but less important. For example, genes are also frequently talked about, but they do not contribute to much of the disease variants that we see within populations or across populations. All of these factors often combine to cause serious blood vessel damage. There are other forms of heart disease like congenital heart disease which are cardiac malformations present in birth and which can manifest at different periods of life. Then you also have heart muscle disease which are basically cardiomyopathies. Then there are some diseases of the heart which are related to infections, like rheumatic heart disease which affects the heart valves but is principally because of the body’s reaction against streptococcal sore throat. And you have other forms of blood vessel disease also called aorta arthritis. But the most frequent ones which are the major killers in the world are coronary heart disease and stroke. Cardiovascular diseases are now by themselves the number one killer in the world. Indeed, according to the global burden of disease study in 2010, ischemic heart disease or coronary heart disease accounted for about 13.3% of global deaths and stroke or brain attack accounted for about 11.1%. Now if you combine coronary and cerebrovascular disease, then together their contribution to global deaths has risen from 1 out of 5 deaths in 1990 to 1 out of 4 deaths in 2010. And you have other problems also now occurring arrhythmias, or electrical disturbances of the heart are increasing, particularly with aging populations and one of the common problems that we are seeing in the elderly now is atrial fibrillation which has risen over 200% between 1990 and 2010. When we look at what the trends in cardiovascular disease death rates are across the world, then we see that in high income countries for example, the United States we find cardiovascular disease death rates are declining over the last 20 or 30 years. In fact they’ve risen sharply in the early part and mid part of the 20th Century and they started declining towards the latter part of the 20th Century and seem to be relatively on a stable decline even now. On the other hand, in developing countries like China and India and elsewhere, in Latin America, and parts of Africa, you are seeing cardiovascular mortality rates rising, particularly age standardized cardiovascular mortality rates are sharply on the rise. In China, cerebrovascular disease or stroke is the prominent form of death. Unlike coronary heart disease is the dominant form of cardiovascular disease in Europe or in United States. This variation between coronary heart disease and stroke is happening across different parts of the world because of different stages of health transition. Now early on in health transition high blood pressure which in one of the most important risk factors for coronary heart disease and stroke results in a bleeding stroke where there is bleeding into the brain from the blood vessels, called hemorrhagic stroke, or hypertensive heart failure where the heart model fails because of longstanding uncontrolled high blood pressure. However as other risk factors are added in the population, like for example increased blood lipids because of abnormal blood fats going up due to unhealthy fat intake or smoking or diabetes, the clotting tendency in the blood increases and the same uncontrolled high blood pressure now results in a clotting stroke and coronary heart disease or blockages in the blood vessels of the heart. So the differences that we see across different regions are not because of marked ethnic differences but because of different pace of progression of the epidemic in different regions of the world. Ultimately it is likely that we will see that most parts of the world will have a very high burden of coronary heart disease and thrombotic stroke. Obviously, many of the risk factors are common, both to stroke and to coronary heart disease. Though blood pressure by and large is the most important risk factor for stroke, it also has other risk factors like smoking, diabetes and abnormal blood fats. But for coronary heart disease, all of these are almost equally important. And then of course you have physical inactivity, dietary issues like reduced fruit and vegetable consumption. All of these which contribute both to coronary heart disease and also to raised blood pressure. Now raised blood pressure also can result in kidney disease. So some people look at hypertension as a disease, others would like to look at it as a risk factor. And then look at what causes high blood pressure? High salt intake, low fruit and vegetable intake, physical inactivity and so on. However way we look at it, it is very clear that high blood pressure and smoking are among the most important risk factors along with physical inactivity and unhealthy diets. And we need to act upon all of them. Now the Framingham study which started in 1948 in the United States in a small village in Massachusetts called Framingham, actually came up with the concept of risk factors and identified smoking, high blood pressure, and high cholesterol as some of the most important risk factors for coronary heart disease. Now we know across the world from studies such as the INTERHEART which studied 52 different populations across the world that virtually all of the world has common risk factors for the heart attack. And by studying people with the first heart attack, they identified that smoking, abnormal fats, high blood pressure, diabetes, abdominal fat deposition, psychosocial risk factors, low intake of fruit and vegetables and lower levels of physical activity and variable intake of alcohol have all been responsible for 90% of the risk in populations across the world for the first heart attack. So much as we may differ in the manifestations of stroke and coronary heart disease at different stages of the epidemic, we recognize that the risk factors are fairly common across the world. And now we are also seeing new risk factors coming up in terms of their contribution being identified. For example we recognize that air pollution is an increasingly incriminated risk factor across the world. Previously this was not thought to be a problem for the heart, it was only thought to be a problem for the lungs. But now we know that air pollution can damage blood vessels everywhere in the body and can result in an increased risk of acute heart attack or even stroke. So we also have to look at other risk factors which are not conventional risk factors. For example, again, in the last 15 to 20 years we have come to recognize that low birth weight also is an important risk factor, particularly if there is a gain in weight between the ages of two and twelve in a low birth weight baby. So what we call rebound adiposity which means an increased amount of body fat at the expense of muscle can happen in such babies and this can set the stage for heart attacks and diabetes and strokes later on in life, especially in early adulthood. We now know that cardiovascular disease is the number one problem all across the world. But in terms of the economic impact, it has a very serious negative influence on developing countries because of the prematurity of deaths. As we know, most of the non-communicable diseases are killers at a younger age in the developing countries and this is true of cardiovascular disease as well. Indeed, about 80% of all cardiovascular deaths occur in the low and middle income countries and most of the premature deaths below the age of 65 years that occur because of cardiovascular disease globally are in these countries. So we have a huge loss of productivity. We have high healthcare costs. Indeed, as a cardiologist, I know that all affairs of the heart are expensive, not merely in the poetic sense. So, we now recognize that even as the epidemic advances most of the deaths in the developing countries are going to be occurring below the age of 70 years, especially below the age of 65 years. And in India for example, it has been estimated , we lost about 9.2 million potentially productive years of life because of premature cardiovascular deaths in the age group of 35 to 64 years and if the epidemic proceeds as projected, we will lose close to about 18 million potentially productive years of life in year 2030. This is 570% more than what the United States lost in the year 2000 and will be 900% more than what the U.S. will lose in that age band in terms of potential productive years by 2030. So developing countries cannot afford this hemorrhaging of human resources in midlife. When we look at what happens to individual families as well we see that many of them are pushed into poverty because they suffer catastrophic health expenditure. In China for example, about 37% of the patients who survive stroke were pushed into poverty and 62% of those without insurance went into poverty. This again brings into question not only the devastating economic effect on families, but also the whole health system issue of whether people have financial protection when they have a serious health problem, whether it’s a stroke or a heart attack. For example, in Kerala in India, we also observed that about 73% of those who survived a cardiovascular event had experienced catastrophic health expenditure. And 50% of them had distressed financing. That means they had to sell some part of their property. Forty percent of the patients who survived lost sources of income. And this again is essentially because of not only the high healthcare costs but because of lack of financial protection. So we not only need to prevent disease, but we also need to bring in universal health coverage in order to take care of people who do develop health problems. But prevention is absolutely the critical priority. And we look at both the population based strategy as well as the high risk strategy when addressing prevention through risk reduction. Now the population based strategy essentially says that the risk factor is distributed across the population. There is a rising gradient of risk at all levels of rising risk factors. So even if you have a blood pressure of 140, you are at a higher risk than a person with a blood pressure of 130 and that person is at a higher risk than a person with blood pressure of 120. So we try and bring about small shifts in the average risk factor levels of the population so that the cumulative benefits across the population are quite massive. But at the same time we try and identify individuals at a high risk, either because of a markedly elevated single risk factor or more commonly because of a combination of multiple risk factors which are modestly elevated. But together they add up to a huge amount of absolute risk. And therefore we try and focus our interventions in terms of therapy which could mean either change in living habits, of diet, giving up smoking, et cetera, or even addition of drugs in people with high risk. But bringing about changes for example in the salt consumption in a population or an increase in fruit and vegetable consumption in a population or increase in physical activity across a population can have huge benefits through population shifts and risk factors. Now even small reductions in the blood pressure, if they occur across a population can result in marked reductions in the number of strokes and heart attacks and the deaths because of those diseases across the population. It might not make much of a difference in terms of clinical management, but across the population, the benefits can be quite huge. And indeed, it has been shown by modeling studies across different countries where the risk factors as well as heart attack death rates have fallen, that more than 50% in most of the countries of the fallen death rates has been attributed to fallen risk factor levels. And less than 50% in most cases in attributable to treatments. We need both but certainly focusing on risk factor reduction through population wide strategies is absolutely a priority. And this is best illustrated by Finland, which in the early ’60s was the table leader in terms of coronary mortality across the world. And many of the people were dying young and therefore the government of Finland initiated a major study called the North Karelia Study in which a large number of behavioral shifts were brought about in the population, partly by changing the nature of the food consumption, including salt reduction in processed foods, increased production of berries instead of dairy products and so on. So a combination of policy and public education resulted over the next 20 years in a dramatic decline in the cardiovascular mortality rates in Finland, making it a sort of poster child for prevention in Europe and elsewhere in the world. And much of this could be attributed to shifts in the population levels of smoking, high blood pressure and cholesterol. Now the Finnish success story is remarkable indeed, between 1971 and 1995, cardiovascular mortality decreased in North Karelia by 73% and by example, the rest of Finland followed and across the nation, it declined by 65%. So we know great changes can be brought about by these kind of interventions at the population level. But at the same time we must recognize that poverty is a major barrier and that is where the problem is within populations of developed countries and also across populations in the low and middle income countries. We talked about the Barker hypothesis where children born malnourished are at a greater risk of cardiovascular disease in later life. And then as they grow up, poor people consume more of tobacco; they are forced to consume unhealthy diets. They have poor access to information and services. And in adult life, because they cannot access health services, onset of cardiovascular disease deprives them of appropriate healthcare, wage loss, job loss or even death, which affects their families. And in the elderly, if they’re uninsured, the high healthcare costs will have a huge out-of-pocket expenditure. We therefore need to act upon risk factors at various levels. And the important thing for us it to distinguish between how we look at risk. Most of the researchers will be looking at what’s called relative risk. That is, does a person who is exposed to a particular risk factor, what is the level of additional risk he or she has as compared to a person who is not exposed? Like a smoker versus a nonsmoker. But that does not tell you how widely prevalent that risk factor is in the population. Now if the risk factor has a high risk in terms of relative risk, but has low prevalence in the population, it does not require as energetic a policy response as a risk factor which has a modest relative risk, but is widely prevalent in the population. Smoking for example, therefore because smoking has a huge population attributable risk, because of its wide prevalence in the population, it requires a very strong policy response. Now there is also something called the absolute risk where multiple risk factors combine in an individual to raise the overall absolute risk of getting a heart attack. Therefore, you may have a person with modest elevation of blood pressure, a modest elevation of cholesterol, each of which may not carry much risk by itself at that level, but cumulatively they carry a huge risk. And particularly if you add smoking to the mix. So in terms of clinical decision-making, absolute risk becomes important. And public health also has to insure that health systems recognize the importance of absolute risk thresholds while managing patients in health system practice. So relative risk for research, absolute risk for clinical decision-making thresholds and population attributable risk for policy. All three are important instruments in public health. And if we actually look at risk factors as the major areas for intervention, we will be able to prevent cardiovascular disease across the population. Remember, today’s risk behaviors are tomorrow’s risk factors. Today’s risk factors are tomorrow’s heart attacks and strokes. So we need to promote healthy behaviors. We need to detect risk factors early and reduce them before they go on to fatal heart attacks or strokes anywhere in the world.
OpenEdition sugere que esta publicação seja citada da seguinte forma:
Pedro Pereira Leite (18 de Maio de 2015). Non-Communicable Diseases VI. Global Heritages. Recuperado em 20 de Julho de 2025 de https://doi.org/10.58079/p2oz