Chronic diseases

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Chronic diseases and associated risk factors in Australia, 2006 (1.06M PDF) Released 16 November 2007

Selected chronic diseases among Australia's children (367K PDF) Released 02 September 2005

Comorbidity of cardiovascular disease, diabetes and chronic kidney disease in Australia (452K PDF) Released 9 August 2007

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This page provides brief overviews of 12 chronic diseases and conditions that have a large impact on the health and quality of life of Australians. The diseases and conditions selected for this page are coronary heart disease, stroke, lung cancer, colorectal cancer, depression, diabetes, asthma, chronic obstructive pulmonary disease, chronic kidney disease, oral diseases, arthritis and osteoporosis.

The choice of chronic diseases was determined by the following criteria:

They show features typical of chronic diseases in their development or clinical course.
They make up a major part of the burden of chronic diseases.
As a group, they are strongly influenced by a limited number of risk factors.
Those risk factors are mostly modifiable at the population and individual level and offer major prospects for prevention.

For further information on the selection process, see the National Public Health Partnership publication Preventing chronic disease: a strategic framework.

Coronary heart disease

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Coronary heart disease (CHD), also known as ischaemic heart disease, refers to the problems associated with a reduced supply of blood to the heart muscle. This is caused by atherosclerosis, when build-ups called 'plaques' form on the inner wall of the arteries that supply the heart itself, the coronary arteries.

CHD has two major forms - heart attack and angina.

A heart attack (often called acute myocardial infarction) occurs when a plaque in a coronary artery suddenly ruptures. This leads to a blood clot that blocks the blood flow to the heart muscle downstream. If the blood flow to the heart cannot be restored quickly enough, the heart muscle will die. It is a life-threatening emergency that can cause severe chest pain, collapse and possible sudden death.
Angina (temporary chest pain) refers to a chest pain that arises when a severely narrowed coronary artery cannot meet a temporary demand to increase the blood flow to the heart. It may be brought on by physical activities or strong emotion. Angina is generally not life-threatening, but can cause much disability. People with angina are more prone to a heart attack.

Although a heart attack is an 'acute' event, CHD is regarded a 'chronic' disease because the condition of angina tends to be chronic, and both forms of CHD (heart attack and angina) are caused by a long-term process (atherosclerosis).

Modifiable risk factors include:

tobacco smoking
physical inactivity
alcohol misuse
poor nutrition
high blood pressure
high blood cholesterol
excess body weight
diabetes

Over the past three decades, advancing medical treatment of CHD and some of its risk factors has improved the quality of life of people with the disease and contributed to reduced mortality. Exercise, rehabilitation and lifestyle modification are beneficial in preventing and controlling CHD.

CHD is the largest single cause of death in Australia. It also contributes significantly to illness, disability, poor quality of life and the associated health care costs in Australia.

Stroke

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Stroke (also known as cerebrovascular disease) occurs when an artery supplying blood to the brain suddenly becomes blocked or bleeds, resulting in the affected part of the brain dying from lack of blood flow. This leads to death or impairment or loss of a range of functions such as body movement and communication.

There are three types of stroke:

ischaemic stroke: when an artery supplying blood to a part of the brain suddenly becomes blocked
haemorrhagic stroke: when an artery supplying blood to a part of brain suddenly bleeds
transient ischaemic attack (TIA): a 'mini stroke' resulting from a temporary reduction of blood supply to part of brain

Ischaemic and haemorrhagic strokes are much more severe than transient ischaemic attacks. Of these, about 85% are ischaemic or 'blockage' strokes, and 15% are haemorrhagic or 'bleeding' strokes.

The principal cause of ischaemic stroke (as with CHD) is atherosclerosis, the partial or complete blocking of arteries due to abnormal build-up of fatty and fibre-like substances on the inner surface of the artery wall, with further blockage by clots formed around such build-ups. Because this process occurs over a long period of time, stroke is considered to be a 'chronic' disease. Poor health outcomes due to stroke are also often long-lasting.

Major risk factors for stroke are:

high blood pressure
high blood cholesterol
tobacco smoking
alcohol misuse
excess body weight
physical inactivity
poor diet and nutrition
diabetes

Stroke is the second leading cause of death and a major cause of disability in Australia. Death can occur very soon after a stroke: about one-fifth of people having a first-ever stroke die within a month and one-third within a year. After one year, about half of stroke survivors remain dependent on others for activities of daily living.

Some patients, particularly those with 'transient' attack, recover within 24 hours. However, transient strokes are a major risk factor for disabling stroke, with a 13-fold increase in the risk of such a stroke in the following year.

Lung cancer

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Lung cancer is a malignant tumour of the lungs. It begins in cells that line the airways and often invades adjacent tissues or spreads elsewhere in the body before symptoms are noticed.

Modifiable risk factors for lung cancer include:

tobacco smoking
environmental tobacco smoke, and
exposure to environmental agents such as asbestos and radon.

Most lung cancers are caused by smoking. The more cigarettes you smoke per day and the longer you have been smoking, the greater the risk of lung cancer.

Lung cancer is the third leading cause of death in Australia and is almost entirely avoidable by not smoking. Most people diagnosed with lung cancer have a short survival time, since it is often diagnosed after the cancer has progressed to a serious stage.

Colorectal cancer

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Colorectal cancer (CRC) comprises cancers of the colon and rectum, the two main sections of the large bowel. It is the most commonly diagnosed cancer in Australia, after skin cancers, and is a major contributor to mortality.

CRC develops from abnormal growths, known as polyps, on the internal linings of the colon and the rectum. Symptoms include blood in the faeces, anaemia, stomach discomfort, changes in bowel habits and unaccountable weight loss.

Survival varies according to the extent of the cancer development at diagnosis. Currently, around 60% of cases survive more than 5 years.

Modifiable risk factors for CRC include:

poor nutrition
physical inactivity
excess weight.

The risk of CRC increases in those with a family history of polyps.

A healthy diet, high in fibre and low in fat, is highly recommended to prevent CRC.

The Australian government is currently planning a population-based screening using faecal occult blood testing for early detection and removal of polyps and cancerous growths.

Depression

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Depression is an affective (mood) disorder characterised by feelings of sadness, loss of interest or pleasure in nearly all activities, feelings of hopelessness, suicidal thoughts or self blame. It is the fourth leading cause of disease burden in Australia, with high associated costs including reduced work productivity, days of lost work, educational failure, poor family functioning, poor social functioning, diminished sense of wellbeing and increased use of medical services. It is also a major risk factor for suicide and self-inflicted injury. Among males in Australia, suicide was the eighth leading cause of death in 2002.

The severity of depression ranges from minor stress to debilitating levels requiring professional help and medication. Usually depressive episodes run a fluctuating course and most people recover within a few years. For some, however, the symptoms persist for a protracted period, and thus depression is classified as a chronic disease.

Risk factors for depression include:

biological and psychological factors:
- family history of depression
- being an adolescent or adult female
- high trait anxiety and pre-existing anxiety disorder
- temperament - reacting negatively to stressors
- negative thought patterns, and
- avoidant coping style
environmental and social factors:
- poverty and unemployment
- conflict and poor parenting practices
- child abuse
- exposure to adverse life events (e.g. relationship break-up, bereavement, family separation, trauma, family illness)
- caring for someone with a chronic physical or mental disorder
- for older adults, being in residential care.

Depression often accompanies other chronic diseases such as cardiovascular disease, diabetes, cancer and rheumatoid arthritis.

There are also a number of recognised protective factors for depression. Having an easy-going temperament and good perceived social support, especially having a relationship with a supportive adult, may help prevent depression. A coping style that favours problem solving is also protective.

Diabetes

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Diabetes mellitus is a chronic condition in which blood glucose levels (hyperglycaemia) are raised due to lack of insulin in the bloodstream, or an inability of the body to use insulin effectively (insulin resistance). The symptoms of diabetes can include excessive thirst, frequent urination and sudden, unexplained weight loss.

There are three types of diabetes mellitus:

Type 1, marked by a total lack of insulin, resulting from the body destroying its own insulin-producing cells in the pancreas
Type 2, marked by reduced levels of insulin, or the inability of the body to use insulin appropriately (insulin-resistance), and
gestational diabetes, which occurs during pregnancy (diagnosed around the 24th-28th week) and disappears after delivery.

Type 2 diabetes accounts for about 85-90% of all cases of diabetes in Australia and is largely preventable. It is classed as a chronic disease because it usually takes several years to develop and persists in most cases for the rest of a person's life.

Modifiable risk factors for Type2 diabetes include:

excess weight, particularly obesity
physical inactivity
poor diet and nutrition.

People with diabetes often have a clustering of risk factors, a condition called the metabolic syndrome. These include obesity, high blood pressure and high blood cholesterol. While high blood pressure and high blood cholesterol are not in themselves risk factors for diabetes, they contribute to increased complications from the disease.

Physical activity plays a protective role against Type 2 diabetes. All other factors being equal, people who undertake regular exercise have a 30% to 60% lower risk of developing Type 2 diabetes than those who do not.

Diabetes is managed with insulin therapy, diet restriction and exercise to maintain normal blood glucose levels.

Links

The Statistics section of this website provides information about the outcomes and impact of diabetes. Because it is often difficult to distinguish between Type 1 and Type 2 diabetes in the various data sets, most of the statistical information refers to all types of diabetes.

Additional information on diabetes is available on the AIHW's Diabetes website.

Diabetes is discussed in a number of AIHW publications, including

Other useful websites
- HealthInsite (DoHA)
- Diabetes Australia

Asthma

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Asthma is a chronic disease marked by episodes of wheezing, chest tightness and shortness of breath associated with widespread narrowing of the airways within the lungs and obstruction of airflow. The underlying problem is chronic inflammation of the air passages, which also tend to over-react by narrowing too easily and too much in response to a wide range of 'triggers', such as:

exercise
viral infections
allergens
environmental irritants (including tobacco smoke and other pollutants)
food chemicals
aspirin and other medications

The symptoms of asthma are usually reversible, either spontaneously or with treatment.

Many people with asthma, particularly those with more severe or persistent symptoms, are allergic to environmental allergens from:

dust mites
cockroaches
pollens
moulds, and/or
pets (especially cats and dogs)

This allergy may also be associated with eczema (particularly in young children) and hay fever.

Some people develop asthma in adulthood; for about 10% of these people, the disease can be attributed to a workplace exposure to specific substances. However, the cause of most cases of asthma is not known.

The disease ranges in severity from mild, intermittent symptoms, causing few problems to the individual, to severe and persistent wheezing and shortness of breath, which may be life threatening and severely impair quality of life. Some young children with mild and occasional episodes of wheezing or cough, particularly those who are not allergic, have a self-limited disease, which resolves in later childhood.

Australia has a high prevalence of asthma, relative to other countries. The disease causes particular problems in children, for whom it is a frequent cause of visits to hospital emergency departments and admission to hospital, and older people, in whom the disease overlaps with chronic obstructive pulmonary disease. Asthma is also a common reason for visits to general practitioners and for use of medications. Hence, it has a substantial impact on health care costs. However, asthma is not a major cause of death in Australia, with less than 400 deaths in 2002.

Chronic obstructive pulmonary disease

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Chronic obstructive pulmonary disease (COPD) is a long-term lung disease marked by shortness of breath that initially occurs with exertion and becomes progressively worse over time. It is a major cause of mortality, illness and disability, making it a leading cause of disease burden in Australia.

COPD most commonly arises from the gradual destruction of lung tissue due to the unopposed action of enzymes stimulated by inhaled irritants. This destruction of lung tissues, known as emphysema, makes the lungs floppy and less able to move air in and out, thereby limiting the ability of the lungs to exchange oxygen and carbon dioxide.

Some patients with COPD also have a persistent cough, producing a small amount of sputum each day. This condition, known as chronic bronchitis, is caused by tobacco smoking and hence often co-exists with emphysema, which is also caused by tobacco smoking. Some other diseases, such as chronic asthma, may also result in COPD by causing irreversible narrowing of the air passages that allow air to move in and out of the lungs.

Tobacco smoking is overwhelmingly the strongest risk factor for COPD. It is estimated that:

About 70% of COPD in men is attributable to smoking
About 60% of COPD in women is attributable to smoking
About 90% of COPD among smokers (men and women) is attributable to smoking
About 71% of deaths from COPD (74% for men and 65% for women) are attributable to smoking.

Environmental agents, including air pollutants, occupational dusts and chemicals, may contribute to the risk of developing COPD, either independently or in conjunction with to tobacco smoking. A small percentage of people with COPD have an inherited deficiency of the enzyme alpha-1-antitrypsin, which normally inhibits the action of destructive enzymes in the lungs.

There is no existing treatment that reverses the destruction of lung tissues underlying COPD. Cessation of smoking has been shown to slow the progression of the disease over a long period. Exercise-based rehabilitation programs improve the quality of life and exercise capacity of persons with COPD. For those with more severe forms of the disease, certain medications help improve exercise capacity and quality of life and reduce the frequency of disease exacerbations.

Chronic kidney disease

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Chronic kidney disease is a debilitating disorder in which kidney functions become progressively worse. The disease contributes substantially to mortality and disability in Australia and is especially prominent in Indigenous populations. Kidney disease can be caused by many conditions that damage the kidneys. Although some kidney disorders may be successfully treated and therefore have no long-term consequence, others remain unresolved and become chronic.

The loss of kidney function follows a path from kidney insufficiency to kidney failure, and progresses eventually to end-stage kidney disease (ESKD). In this stage, there is a severe reduction in kidney function such that dialysis or kidney transplantation is necessary to maintain life. ESKD is irreversible and incurable with attendant high morbidity and mortality.

A number of factors contribute to the development and progression of chronic kidney disease.

Glomerulonephritis, a group of kidney diseases caused by inflammation and gradual, progressive destruction of the internal kidney structures, is the leading cause of kidney failure in Australia. Glomerulonephritis may be triggered in some persons by exposure to stimuli such as streptococcal infections.
Diabetes is the second most common cause of deterioration of the kidneys. Diabetes damages both the small and large blood vessels in the body, thus affecting kidney functions. Good control of blood sugar levels in diabetics can delay or avoid damage to the kidneys.
High blood pressure, a controllable and reversible risk factor, may also lead to kidney impairment. Increased pressure in the arteries and vessels of the kidneys may cause them to become narrowed and thickened, impairing the filtering ability of the vessels. In persons with diabetes, high blood pressure further increases the risk of damage to the blood vessels of the kidneys.
Infections such as skin sores and scabies have been found to be associated with kidney disease, especially among Indigenous Australians.

Lifestyle factors also increase the risk of kidney disease. These include:

excess weight
tobacco smoking
long-term use of analgesic compounds and related agents.

In the early stages of chronic kidney disease, treatment and management focus on delaying progression to ESKD and controlling complications. Interventions include:

maintaining good blood pressure
controlling blood glucose
maintaining healthy blood cholesterol
a diet low in sodium, potassium and protein.

Once progression to ESKD has occurred, two major treatment options - dialysis and kidney transplantation - are available to sustain life.

Dialysis is a method of removing excess water and waste products from blood when the kidney no longer can. It typically combined with a diet to reduce the wastes that build up in the blood and to maintain nutritious elements. Dialysis aids the survival of patients with ESKD.
Transplantation involves the surgical replacement of a patient's kidney with one from a donor. It offers a better chance for long-term survival than dialysis. In recent years there have been improvements in the survival of persons with kidney transplants. Of people who had a kidney transplant in 1983, 58% had a functioning transplant 5 years later, increasing to 76% of those who had a transplant in 1997.

Oral diseases

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Oral diseases continue to be among the most costly yet preventable health problems, resulting in high direct and indirect costs to individuals and governments. They commonly cause pain, discomfort, and problems with eating, speech, communication and socialising. While most oral diseases are not associated with mortality, there are some deaths related to oral cancers.

There are two main forms of oral diseases:

Dental caries (tooth decay), caused by acid-producing bacteria that live in the mouth. Tooth decay progresses from demineralisation of the tooth or its root to infection of the tooth pulp, abscess formation, fracture of the tooth, and tooth loss.
Periodontal (gum) diseases, a group of inflammatory diseases that affect the gums, deeper connective tissues and the jaw bone, all of which support and protect the teeth. These cause swelling of the periodontal tissue which can be associated with the recession of the gums or formation of periodontal pockets in the gums. A common outcome is lack of support for the tooth resulting in tooth mobility, formation of gum abscesses and tooth loss.

Other oral diseases include mouth ulcers, dental and gum problems, oral cancer, tooth impactions, misaligned teeth and jaws, and trauma to teeth and mouth.

Oral diseases are considered 'chronic' in that the underlying causes involve long-term processes that can result in irreversible tissue destruction and which can re-occur over the course of a lifetime.

Modifiable risk factors for dental caries and gum disease include:

lack of water fluoridation
infrequent dental visits
excess of sweet or sticky foods
medication that alters saliva flow
tobacco smoking
inadequate tooth-brushing or flossing of gums and teeth.

Dental caries and periodontal diseases are preventable and treatment is available via interventions to limit progress, alleviate pain and suffering and restore function. Public health programs such as water fluoridation and school dental services are also essential for primary prevention, education and awareness raising.

Arthritis

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Arthritis is a group of conditions in which there is inflammation of the joints, causing pain, stiffness, disability and deformity. The two most common forms of arthritis are rheumatoid arthritis and osteoarthritis.

Rheumatoid Arthritis

Rheumatoid arthritis is an auto-immune disease (when the person's immune system attacks its own body tissues) involving chronic inflammation of the joints, beginning with the membranes lining the joints then spreading to other joint tissues. The inflammation may damage cartilage in the joint and erode adjacent bones. This damage and reduced use of the joint can lead to deformities. It is most common in the joints of the fingers, toes, wrists, knees, elbows and ankles, and usually occurs symmetrically (affecting both sides of the body at the same time).

Rheumatoid arthritis occurs mostly in people aged 20 and above. However, juvenile rheumatoid arthritis is another form of the condition that occurs in children, causing fever, rash, enlarged spleen, pain, disability and activity restrictions. Often juvenile rheumatoid arthritis improves or remits at puberty with minimal functional loss and deformity.

There are no well-established behavioural risk factors for rheumatoid arthritis.

Early diagnosis and aggressive treatment with disease-modifying antirheumatic drugs are important in treating rheumatoid arthritis. A range of new drugs, particularly the monoclonal antibodies, can significantly improve outcomes, at least in the short term. Surgical joint replacement also can be considered, but it does not appear to cure the disease.

Osteoarthritis

Osteoarthritis is a degenerative condition due mainly to accumulated wear of a joint. It mainly affects the hands, spine and weight-bearing joints such as the hips, back, knees and ankles. The condition begins in the cartilage (protective cushion for the bones forming a joint), by gradually wearing away the tissue and disrupting normal function of the joint. The condition progresses from initial pain after activity to pain after minimal movement or even during rest.

Relatively few people at younger ages report having osteoarthritis, but by age 65 nearly 30% of females and 18% of males in Australia report having the condition.

Modifiable risk factors for osteoarthritis include:

joint trauma and injury
obesity
repetitive occupational joint use
physical inactivity

In most cases osteoarthritis can not be completely cured, but it is possible to provide relief and delay its progression. Weight loss and exercise to strengthen bones and muscles are important, along with anti-inflammatory drug such as COX-2 inhibitors. In advanced cases not responding to treatment, surgical joint replacement is a cost-effective intervention.

Osteoporosis

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Osteoporosis is a progressive loss of bone density which occurs when calcium dissolves from the bones leaving them porous and weak. This condition is a major contributor to fractures in the elderly due to the deterioration in the architecture and strength of the skeleton. Females are at increased risk of developing the condition as they begin menopause due to the deficiency of oestrogen which has a central role in maintaining and balancing bone mass.

Osteoporosis is a major cause of morbidity, deformity, disability and poor quality of life due to fractures and related complications. Osteoporotic fractures are usually precipitated by falls or by lifting a heavy weight. The fractures impair physical functions, often leading to dependency in older people and reduced quality of life.

Modifiable risk factors for osteoporosis include:

low body weight
low calcium intake
low vitamin D intake
physical inactivity
tobacco smoking
alcohol misuse, and
use of corticosteroids.

It is easier to prevent than to treat established osteoporosis. At present there are no approved drug treatments to increase bone density once it is lost.

There are two main approaches to the prevention of osteoporosis:

Optimising the attainment of peak bone mass, begins in childhood and includes maintaining a good diet with an adequate intake of calcium. An active lifestyle, with an emphasis on weight-bearing physical activities such as walking, is also important, as is discouraging smoking and excessive alcohol consumption.
Slowing the rate of bone loss with ageing. A number of drug treatments, including hormone replacement therapy (HRT), are available. For females, oestrogen replacement started at the time of menopause seems to retard or prevent bone loss and reduce fracture risk for as long as the oestrogen is taken.

The risk factors for falling should also be addressed as part of an osteoporosis prevention program. An environmental assessment to help older persons 'fall-proof' their living areas is advisable. Typical actions from such assessments include installing optimal lighting; providing hand rails on stairs, toilet and bath areas; removing throw rugs and extension cords; placing soft corners on cabinets and furniture; and providing appropriate footwear to prevent tripping.