Lecture 6

Epidemiology of chronic non-communicable diseases.

Cardiovascular diseases as a medico-social problem

• •

Cardiovascular diseases

In the second half of the XX century noninfectious diseases began to represent the basic health hazard for the population and became a problem for public health services. During the past 80 years, the developed world has experienced a dramatic change in the pattern of disease. By far the greatest part of this development has been the decline of many of the infectious diseases (e.g., tuberculosis, typhoid fever, polio, diphtheria). In the first place now there are cardiovascular diseases that are the leading reasons of death rate and physical disability of adult population in the majority of economically developed countries of the world.

Cardiovascular diseases (CVD) comprise of a group of diseases of the heart and the vascular system. The major conditions are ischaemic heart disease (IHD), hypertension, cerebrovascular disease (stroke) and congenital heart disease Rheumatic heart disease (RHD) continues to be an important health problem in many developing countries.

Cardiovascular diseases are the number one cause of death in the world

Problem statement

• • In today's world, most deaths are attributable to non communicable diseases (32 million) and just over half of these (16.7 million) are as a result of CVD; more than one-third of these deaths occur in middle-aged adults. In developed countries, heart diseases and stroke are the first and second leading cause of death for adult men and women. These facts are familiar and hardly surprising, however, surprisingly in some of the developing countries. CVD have also become the first and second leading causes responsible for one-third of all deaths

.

The are four patterns of CVD mortality at four different stages of epidemiological transition:

1.

2.

Deaths caused by cardiovascular diseases at four different stages of the epidemiological transition Stage

CVD deaths (% of total) Predominant CVD Affected SEAR populations

Age of pestilence and famine Age of receding pandemics

5-10 10-35

RHD, infectious and nutritional cardiomyopathies As above plus hypertensive heart disease haemorrhagic stroke

Some rural areas SEAR as a whole-rural population 3.

Age of degenera tive and man made diseases

35-55

All forms of stroke, IND at relatively young age

Urban population 4.

Age of delayed degenerative diseases

<50

Stroke and IND at older ages

• Developing countries of South East Asia Region are typically in the second stage of this transition. While some rural population are still in stage one, many urban populations have entered third stage characterized by very high CVD mortality.

• •

Problem statement in the world

The incidence of CVD is greater in urban areas than in rural areas reflecting the aquisition of several risk factors such as tobacco consumption, lack of physical activity, unhealthy diet (today's fast food habits) and obesity. A peculiar cause of concern is the relative early age of CVD deaths in the developing countries.

Ironically treatment.

CVDs are now in decline in the industrialized countries first associated with them.

They seem to have crossed the peak of the epidemic by now. The decline is largely a result of the success of primary prevention and to a lesser extent, The middle and low-income countries are at the mid point of the emerging epidemic and will face its full impact in the coming years. These countries can be benefited from the strategy of primary prevention.

INDIA

• In India an estimated 2.27 million people died due to CVD during 1990, and according to projections the number of deaths due to CVD was to increase from 3.3 million by 2010. There were over 5 million persons suffering from CVD during 1999. The prevalence of CVD is reported to be 2-3 times higher in the urban population as compared to the rural population. In one study, the prevalence of IHD among adults was estimated at 96.7 per 1000 population in the urban and 27.1 per cent in rural areas

.

•

The present mortality rates are the consequence of previous exposure to behavioral risk factors such as inappropriate nutrition, insufficient physical activity and increased tobacco consumption. It is called the "lag-time" effect of risk factors for CVD. Overweight, central obesity, high blood pressure, dyslipidaemia, diabetes and low cardio-respiratory fitness are among the biological factors contributing principally to increased risk.

• It is now well established fact that a persistently high cholesterol level can almost certainly precipitate a cardiac event such as CHD.

Still most people do not have an idea of nutritional requirements and a balanced diet. Unhealthy dietary practices include a high consumption of saturated fats, salt and refined carbohydrates, as well as a low consumption of vegetables and fruits and these tend to cluster together.

• • • • •

Coronary heart disease

• The principal causes forming a high death rate due to cardiovascular diseases is ischemic heart disease (35 - 40

%

in the structure of all causes of death at the given class)

.

• Ischemic heart disease (syn: Coronary heart disease - CHD) has been defined as “impairment of heart function due to inadequate blood flow to the heart compared to its needs, caused by obstructive changes in the coronary circulation to the heart”. The WHO has drawn attention to the fact that CHD is our modern “epidemic”, i.e., a disease that affects populations, not an unavoidable attribute of ageing. CHD may manifest itself in many presentations:

angina pectoris of effort myocardial infarction irregularities of the heart cardiac failure sudden death The natural history of CHD is very variable. Death may occur in the first episode or after a long history of disease.

Epidemicity

• "Epidemics" of CHD began at different times in different countries.

In United States, epidemics began in the early 1920s

;

in Britain in the 1930s

;

in several European countries, still later. And now the developing countries are catching up. For example, in Singapore, the standardized death rate from CHD doubled in 20 years, rising from 22 per 100,000 populations in 1957 to 50 per 100,000 populations in 1979

.

Similar, trends have been noted in some other developing countries, e.g. Malaysia, Mauritius and Sri Lanka.

• Countries where the epidemic began earlier are now showing a decline. For example, in United States, where the epidemic began in early 1920s, a steady decline was evident by 1968, and a 25 per cent fall in mortality (not morbidity) by 1980. Substantial declines in mortality have also occurred in Australia, Canada and New Zealand.

• Several European countries where the epidemic came later, have registered little or no change in rates (e.g., Hungary, Poland). In Great Britain, the epidemic has not shown any decline.

• • The decline in CHD mortality in US and other countries has been attributed to changes in life-styles and related risk factors (e.g., diet and diet-dependent serum cholesterol, cigarette use and exercise habits) plus better control of hypertension

.

• The reasons for the changing trends in CHD are not precisely known. The WHO has completed a project known as MONICA "(multinational monitoring of trends continue for a 10 year period ending in 1994.

and determinants between social class and CHD in developed countries

.

in.

cardiovascular diseases)" to elucidate this issue. Forty-one centres in 26 countries were participating in this project, which was planned to • When CHD emerged as the modern epidemic, it was the disease of the higher social classes in the most affluent societies. Fifty years later the situation is changing; there is a strong inverse relation

To summarize, in many developed countries, CHD still poses the largest public health problem. But even in those showing a decline, CHD is still the most frequent single cause of death among men under 65.

International variations

• CHD is a world-wide disease. Mortality rates vary widely in different parts of the world. The highest coronary mortality is seen at present in North Europe and in English-speaking countries (e.g., Scotland, Northern Ireland, and Finland). On the other hand rates in southern Europe are much lower (e.g. Italy, France), and those in Japan, although a rich industrialized country, are extremely low.

Coronary heart disease in India

• A large body of data exists on the occurrence of CHD in hospital patients. However, there are only two studies on its prevalence in the general population. On screening of persons over the age of 30 years by a 12-lead ECG, in Chandigarh (urban population) the prevalence was found to be 65.4 and 47.8 per 1000 males and females respectively

.

In a village in Haryana the prevalence was 22.8 and 17.3 per 1000 males and females respectively

.

• The pattern of CHD in India has been reported to be as follows: a) CHD appears a decade earlier compared with the age incidence in developed countries. The peak period is attained between 51-60 years b) males are affected more than females c) hypertension and diabetes account for about 40 per cent of all cases d) heavy smoking is responsible aetiologically in a good number of cases.

•

Cardiovascular diseases in Russia

• In the 1990s in Russia there was the extremely adverse situation concerning cardiovascular pathology. Annually, from 15 to 17 million patients with cardiovascular diseases are registered in the country. More than half of all cases of death, 43.3

%

of cases of physical disability, 9.0% of temporary invalidity occur due to cardiovascular diseases.

The share of diseases of blood circulation system in structure of death rate of Russia population has not changed essentially for the last ten years, however at the background of growing death rate general index in the ninetieth, naturally, both the absolute number of died because of this pathology, and the index of mortality caused by the diseases of blood circulation system grew also. Thus, from 1990 till 2000 the index of death rate because of the diseases of blood circulation system has increased from 618.9 to 844.0 per 100 thousand persons.

Statistics of cardiovascular diseases in Russia

• At the same time in the structure of primary morbidity of the population 3.5% fall to the share of blood circulation system diseases, and the prevalence index is about 15%. First of all it is connected with the low detect ability of the given pathology and low appeal ability of the population for medical aid. So, special researches show, that, for example, among men at the age of 40 59 years almost 30% of those suffering from hypertension did not know, that they were ill; up to 60% of ischemic heart disease patients did not know about their disease.

•

Many cardiovascular diseases, starting to develop in the childhood, give the first symptoms alarming the patient when the disease has come already too far. For example, at ischemic heart disease the patient starts to feel its manifestations when of coronary arteries has constricted by 75% and more.

• However both primary disease incidence of blood circulation system and their prevalence grow during last years. Only for the period from 1997 to 2005 prevalence of this pathology has increased from 146.5 to 220.1‰, and primary disease incidence – from 17.2 to 29.1‰.

Age and sex features of CVD in Russia

•

Blood circulation system morbidity has its age and sex features.

According to the appeal ability data the morbidity level at women is 1.4 times higher, than at men. With aging prevalence of these diseases grows intensively. However, for recent years this pathology has become younger. Arterial hypertension incidence at teenagers has increased more than three times for the last 25 years. Increase of arterial pressure occurs more often at boys in pubertal period, and 20-25% of teenagers with arterial hypertension develop essential hypertension in older age.

• Blood circulation diseases cause a considerable economic damage to the state due to morbidity, invalidism and mortality. According to experts’ estimation, the economic damage only from arterial hypertension, ischemic heart disease and cerebrovascular diseases makes about 30 billion rubles annually.

Prevention of CVD

• • • • At present, the concept about risk factors of this pathology is the basis of primary prevention of blood circulation diseases. Today, by carrying out numerous medical and social researches it became possible to reveal the risk factors authentically influencing formation of the given class of diseases. They can be divided into two groups: controllable and uncontrollable. Sex, age, hereditary susceptibility is related to uncontrollable factors. Elimination or softening of controllable factors influence underlies the base of preventive strategy. The World Health Organization referrers to them:

Factors of a way of life

(smoking, bad diet, excess body weight, low physical activity, alcohol abuse, and use of narcotic drugs);

Biological factors

(the high arterial pressure, the raised level of cholesterol in blood, diabetes);

Psychosocial factors

vulnerability, etc.).

(stress, tiredness at work, social

Prevention of CVD

• Besides, the abovementioned risk factors sometimes are divided according to another principle: primary, or external (smoking, alcohol abuse, irrational diet, the use of drugs, hypodynamia, emotional psychosis and stress), and secondary, or internal (diabetes, arterial hypertension, hypercholesterolemia, allergy, immunodeficiency).

• Today each two adult persons out of three have one and more risk factors of cardiovascular diseases. In Russia, according to the official statistics, only 5 million persons have the increased blood pressure, and special random researches show, that the number of such patients reaches 42 million persons, or about 30 % of the population of the country. At the same time the persons with high arterial pressure develop ischemic heart disease 3-4 times more often, and a stroke – 7 times.

• This situation becomes more and more serious, as in the persons with more than one significantly increased.

risk factor, even at their moderate expressiveness; the risk of cardiovascular diseases is even more

Prevention and Control

• Decrease in death rate of the population in a number of world regions is connected basically with the fact that the population of these countries has changed the wrong way of life and has got habits of a healthy way of life. It follows from this that the attention in the field of public health services should be given to risk factors decrease. Work on their prevention should be carried out in two directions: the preventive maintenance focused on the whole population, and the preventive maintenance focused on persons with high-risk occurrence of blood circulation diseases.

• A broader concept is emerging, that is, to develop an overall integrated programme for the Prevention and Control of NCDs as part of primary health care systems, simultaneously attacking several risk factors known to be implicated in the development of non-communicable diseases. Such concerted preventive action should reduce not only cardiovascular diseases but also other major NCDs, with an overall improvement in health and length of life.

Key messages to protect heart health:

• Heart attacks and strokes are major - but preventable - killers worldwide. • Over 80% of cardiovascular disease deaths take place in low-and middle income countries and occur almost equally in men and women. Cardiovascular risk of women is high particularly after menopause. • Tobacco use, an unhealthy diet, and physical inactivity increase the risk of heart attacks and strokes. • Cessation of tobacco use reduces the chance of a heart attack or stroke. • Engaging in physical activity for at least 30 minutes every day of the week will help to prevent heart attacks and strokes. • Eating at least five servings of fruit and vegetables a day, and limiting your salt intake to less than one teaspoon a day, also helps to prevent heart attacks and strokes. • High blood pressure has no symptoms, but can cause a sudden stroke or heart attack. Have your blood pressure checked regularly. • Diabetes increases the risk of heart attacks and stroke. If you have diabetes control your blood pressure and blood sugar to minimize your risk. • Being overweight increases the risk of heart attacks and strokes. To maintain an ideal body weight, take regular physical activity and eat a healthy diet. • Heart attacks and strokes can strike suddenly and can be fatal if assistance is not sought immediately.