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Cerebrovascular disease (stroke)

Epidemiology of Specific Chronic Diseases: Cardiovascular Disease

Cardiovascular Disease (CVD) includes all diseases of the heart and blood vessels.

Cardiovascular disease includes two major sub-types which are discussed below:

Epidemiology

  • Each year CVD causes an estimated 17 million deaths worldwide, accounting for one-third of all deaths worldwide. More than one-third of these deaths occur in middle-aged adults.
  • In developed countries heart disease and stroke are the first and second leading cause of death among adult men and women.
  • However, the burden of CVD in developing countries has increased significantly. Twice as many deaths from CVD occur in developing countries as in developed countries3.  Overall, in developing countries CVD ranks third in disease burden.
  • By 2010 CVD is estimated to be the leading cause of death in developing countries3.
  • CVD are the main cause of death in the UK, accounting for just under 233,000 deaths in 2003. More than 1 in 3 people (38%) die from CVD5.
  • The main forms of CVD are coronary heart disease (CHD) and stroke. About half of all deaths from CVD are from CHD and about a quarter are from stroke5.

 

Coronary Heart Disease (CHD)

Description
Disease of the blood vessels supplying the heart muscle.

The primary cause of CHD is atherosclerosis (the hardening and narrowing of the arteries due to the build-up of fatty material and plaque) that reduces blood flow through the coronary arteries to the heart muscle. Reduced or cut-off blood flow andoxygen supply to the heart muscle can result in angina, heart attack and lead to heart failure and arrhythmias.

CHD presents in two main forms: myocardial infarction (heart attack) and angina.

Epidemiology

  • Coronary heart disease is now the leading cause of death worldwide. An estimated 3.8 million men and 3.4 million women die each year from CHD1.
  • In developed countries heart disease is the leading cause of death in men and women2. In Europe CHD accounts for an estimated 1.95 million deaths each year4.
  • CHD is the most common cause of deaths in the UK. An estimated 1 in 5 men and 1 in 6 women die from the disease each year5.
  • In 2003 CHD caused around 114,000 deaths in the UK5.
  • CHD is responsible for 110,000 deaths in England each year. More than 1.4 million suffer from angina and 275,000 people have a heart attack annually5.
  • Death rates from CHD have been falling in the UK since the late 1970s. For people <65 years, they have fallen by 44% in the last ten years5. A recent study has suggested that 58% of decline in CHD during the 1980s and 1990s was attributable to reduction in major risk factors, principally smoking. Treatments to individual, including secondary prevention explained the remaining decline in mortality5.
  • However despite recent declines the UK has a relatively high death rate from CHD. Among more developed countries only Ireland and Finland have a higher rate than the UK5.
  • Death rates from CHD are highest in Scotland and Northern England. The premature death rate for men living in Scotland is 67% higher than in the South West of England and 84% higher for women5.
  • Significant socio-economic differences in the mortality for CHD are evident. The premature deaths rate from CHD at the end of the 1980s for male manual workers was 58% higher than for male non-manual workers, while the premature death rate from CHD for female manual workers was more than twice as high5.
  • The highest deaths rates for CHD in the UK have been observed among South Asians (Indians, Bangladeshis, Pakistanis and Sri Lankans).

Risk Factors
It is estimated that 80-90% of people dying from CHD have one or more major risk factors that are influenced by lifestyle1.

The major modifiable risk factors for the development of CHD include;

Hypertension
High blood pressure is a major risk factor for heart disease. In people aged up to 50 years, both Diastolic Blood Pressure (DBP) and Systolic Blood Pressure (SBP) are associated with cardiovascular risk. In persons aged over 50 years SBP is a far more important predictor of risk1.

Raised serum lipids
High levels of LDL-cholesterol and other abnormal lipids is a major risk factor for the development of CHD.

The World Health Report estimates that >60% of  CHD around 40% of ischaemic stroke in developed countries is due to total blood cholesterol in excess of the theoretical minimum (3.8mmol/1)3.

Smoking
Smoking is a major risk factor for CHD. Cigarette smoking promotes atherosclerosis and increases the levels of blood clotting factors such as fibrinogen. Nicotine also accelerates heart rate and raises blood pressure1.

In Europe, smoking causes an estimated 32% of deaths from cardiovascular disease (CVD) in men aged 35-69 years and 6% of CVD deaths in women of the same age4. 

Diabetes mellitus
Diabetes substantially increases the risk of CHD. Men with type 2 diabetes have a 2-4 fold greater annual risk of CHD, while women have an annual 3-5 fold greater risk of CHD. Diabetes also magnifies the effect of other risk factors including, raised cholesterol levels, raised blood pressure, smoking and obesity5.

Diet
Several aspects of dietary patterns have been linked to the increased risk of CHD. These include diets high in saturated fats and cholesterol, and high salt intake and diets with low fruit and vegetable intake. The World Health Report 2002estimates that approximately 30% of CHD in developed countries is due to fruit and vegetable consumption levels below 600g per day3.

Physical inactivity
It is estimated that physical inactivity increases the risk of heart disease by 50%1.

Physical inactivity also impacts on other risk factors for CHD including obesity, blood pressure, high triglycerides, a low level of HDL and diabetes.

Obesity
As well as being an independent risk factor for CHD, obesity is a major risk factor for high LDL cholesterol and triglyceride levels and to lower HDL cholesterol, high blood pressure and diabetes4.

Other modifiable risk factors
Low socio-economic status
Mental ill health
Psychosocial stress
Alcohol use
Use of certain medications, including some oral contraceptives and hormone replacement therapy.
Excess homocysteine in blood.
Inflammation.
Abnormal blood coagulation.

Age

Family history of CHD
Increased risk if a first-degree blood relative has had coronary heart disease before age 55 (male relative) or 65 years (female relative)1.

Gender
Higher rates of CHD among males than females.

Ethnicity

Prevention and Screening
Reduce major risk factors for CVD.

References

  1. Mackay J, Mensah G, eds. The Atlas of Heart Disease and Stroke, World Health Organization, Geneva, 2004.
     
  2. National Statistics, Health Statistics Quarterly 30, Spring 2006.
     
  3. World Health Organization. The World Health Report 2002. Reducing risks, Promoting Healthy Life. World Health Organization: Geneva, 2002.
     
  4. Peterson S, Peto V, Rayner M. European cardiovascular disease statistics - 2005 edition, British Heart Foundation Health Promotion Research Group, Department of Public Health, University of Oxford.
     
  5. Petersen S, Peto V, Scarborough P, Rayner M.  2005 Coronary Heart Disease Statistics - 2005 edition, British Heart Foundation Health Promotion Research Group, Department of Public Health, University of Oxford, 2006. Available online at: http://www.heartstats.org

 

Cerebrovascular Disease (Stroke)

Description
Two main categories;

  1. Ischaemic strokes
    Account for 80% of strokes.
    Two main categories: thrombotic strokes and embolic strokes.

Thrombotic strokes may be preceded by one or more transient ischaemic attacks (TIAs). About 15% of embolic strokes occur in people with a trial fibrillation.

  1. Haemorrhagic Stroke

About 20% of strokes are caused by haemorrhage.

Epidemiology

  • Annually 15 million people worldwide suffer a stroke. Of these 5 million die and another 5 million are left permanently disabled6.
  • Stroke is the third most common cause of death in developed countries.
  • Uncommon in persons <40 years.
  • Incidence in many developed countries is declining, largely as a result of better control of high blood pressure and reductions in tobacco use. However, the absolute numbers of stoke continues to increase because of ageing populations6.
  • Deaths rates from stroke for people <65 years have fallen by 23% in the last 10 years. Recently rates have declined at a slower rate particularly among younger age groups7.

Risk Factors

  • Same as for CHD.
  • The most important modifiable risk factor for stroke is high blood pressure; for every 10 people who die of stroke, 4 could have been saved if their blood pressure had been regulated6.
  • Smoking - among persons aged >65 years, two-fifths of deaths from stroke are linked to smoking.
  • Atrial fibrillation, heart failure and heart attack are other important risk factors6.
  • Previous stroke

References

  1. Mackay J, Mensah G, eds. The Atlas of Heart Disease and Stroke, World Health Organization, Geneva, 2004.
     
  2. Peterson S, Peto V, Scarborough P, Rayner M.  2005 Coronary Heart Disease Statistics - 2005 edition, British Heart Foundation Health Promotion Research Group, Department of Public Health, University of Oxford, 2006. Available online at; http://www.heartstats.org

© CM Kirwan 2006