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 noncommunicable 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:
Deaths caused by cardiovascular diseases at four
different stages of the epidemiological transition
Stage
CVD
deaths (% Predominant CVD
of total)
1. Age of pestilence
5-10
2.
10-35
and famine
Age of receding
pandemics
3. Age of degenerative and man
made diseases
4. Age of delayed
degenerative
diseases
35-55
<50
RHD, infectious and
nutritional
cardiomyopathies
As above plus
hypertensive heart
disease haemorrhagic
stroke
All forms of stroke,
IND at relatively
young age
Stroke and IND at
older ages
Affected SEAR
populations
Some rural
areas
SEAR as a
whole-rural
population
Urban
population
• 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 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,
treatment.
• The middle and low-income countries are at the midpoint 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 and determinants in.
cardiovascular diseases)" to elucidate this issue. Forty-one centres in
26 countries were participating in this project, which was planned to
continue for a 10 year period ending in 1994.
• 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
between social class and CHD in developed countries.
• 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)
b)
c)
d)
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:
CHD appears a decade earlier compared with the age incidence in
developed countries. The peak period is attained between 51-60
years
males are affected more than females
hypertension and diabetes account for about 40 per cent of all
cases
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 4059 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 (stress, tiredness at work, social
vulnerability, etc.).
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 risk factor, even at their moderate
expressiveness; the risk of cardiovascular diseases is even more
significantly increased.
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 middleincome 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.