Chronic diseases

Introduction

Chronic diseases, also known as non-communicable diseases, can be defined as diseases that have lasted, or are expected to last, more than six months. The World Health Organization (WHO) estimates that approximately 41 million people die from chronic diseases each year globally, which is equivalent to 74% of all deaths.¹ Chronic diseases are often associated with older age groups, but are also strongly related to modifiable risk factors such as tobacco smoking, risky alcohol consumption, unhealthy diet and physical inactivity.²

In Australia, most of the disease burden was from chronic diseases.³ As Australia’s population ages the number of people with chronic diseases, and associated health burden, will increase.

Chronic disease burden

For the subset of chronic conditions included in this section, the number and age-standardised rate (ASR or standardised rate) of years of healthy life lost in 2022 were:

• Coronary heart disease (CHD): 305,620 years (standardised rate 9.0 per 1,000 persons)
• Chronic obstructive pulmonary disease (COPD): 203,573 years (standardised rate 5.9 per 1,000 persons)
• Asthma: 138,041 years (standardised rate 5.3 per 1,000 persons)
• Type 2 diabetes: 125,512 years (standardised rate 3.8 per 1,000 persons)
• Stroke: 123,308 years (standardised rate 3.6 per 1,000 persons).

Corresponding disease expenditure for 2019–20 was $2.392 billion (coronary heart disease), $994.8 million (COPD), $899.9 million (asthma), $1.994 billion (type 2 diabetes) and $893.5 million (stroke).⁴

Selected health conditions

This section focuses on selected health conditions that cause high levels of morbidity and mortality but that are also preventable. It includes information from a large, regularly administered, national survey, hospitalisation data and mortality. Because much of the treatment and management of these conditions occurs in other settings, hospitalisations will under-estimate the impacts of these conditions.

Asthma

Asthma is a major, long-term disease of the respiratory system that affects both children and adults—it is one of the most common chronic diseases of childhood. Asthma is characterised by inflammation and narrowing of the small airways in the lungs leading to symptoms of cough, wheeze, shortness of breath and tightness in the chest.

Genetic susceptibility interacting with environmental factors, particularly in early childhood, increases the risk of developing asthma. There are many triggers that cause exacerbations (flare-ups) of asthma including exercise, viral infections, smoke, fumes, pollen, animal fur and feathers and changes in the weather. Asthma cannot be cured but can be managed appropriately with short- or long-term inhalers that open airways, relieves symptoms and reduce inflammation. In severe cases, asthma can lead to death.

Chronic obstructive pulmonary disease

COPD refers to a collection of preventable chronic conditions of the respiratory system that narrow the airways, obstruct airflow, and make it hard to breathe. Breathlessness is a common symptom, as is chronic cough with or without excess production of mucus and unusual tiredness. Some conditions that contribute to COPD are emphysema and chronic bronchitis. It is the 5th ranked leading cause of death for males and females in 2016–2020.

The most significant risk factor is smoking and exposure to tobacco smoke. Other factors are occupational exposure to dusts and chemicals, air pollution, having asthma, genetics, a history of frequent respiratory infections in early childhood and exposure to burning fuels which primarily occurs in developing countries. Comorbidities such as asthma, heart disease or diabetes can affect COPD and how it is managed.

Diabetes

Diabetes is a chronic disease that occurs when either the pancreas does not produce enough insulin, a hormone that controls blood glucose, or when the body cannot effectively use the insulin it produces. Raised blood sugar (hyperglycaemia) is a common effect of diabetes and, if uncontrolled, leads to serious damage to many body systems.

• Type 1: formerly called insulin-dependent diabetes is characterised by insufficient insulin production that requires daily administration of insulin. The causes of Type 1, and how to prevent it, remain largely unknown, however, it is thought to be due to an auto-immune reaction that destroys the cells in the pancreas that make insulin. There is an increasing body of evidence implicating certain viral infections in the development of Type 1 diabetes.
• Type 2: formerly called non-insulin dependent diabetes results from the body’s ineffective use of insulin and is largely the result of excess body weight and physical inactivity. Type 2 diabetes used to be seen only in adults, but the prevalence of the disease is rising in younger age groups.
• Gestational: occurs during pregnancy and is characterised by hyperglycaemia. Leading risk factors are older age, excess body weight, certain racial and ethnic backgrounds, certain medications (for example steroids) and polycystic ovary syndrome. It is the fastest growing type of diabetes in Australia. Poorly controlled gestational diabetes increases the risk of complications during pregnancy and at delivery. Gestational diabetes increases the risk of the infant developing Type 2 diabetes later in life.

Coronary heart disease

CHD is the most common heart disease within the group of conditions known as cardiovascular diseases (CVD). CHD was the leading cause of death for males and ranked 2nd for females for the period 2016–2020. It is caused by a build-up of plaque that clogs or narrows coronary arteries and reduces blood flow and oxygen to the heart. Many people are unaware that they have CHD until it causes a heart attack.

Plaque is made up of fat, cholesterol and other materials and its build-up is related to things like genetics, age, and modifiable lifestyle factors. While there are several risks that a person cannot change, things such as eating healthier and being active, quitting smoking, controlling weight, diabetes, blood pressure and cholesterol can reduce the likelihood of developing this condition, having a heart attack, and improve recovery after a heart attack.

Stroke

Stroke is the most common condition in the CVD group. Stroke is the term commonly applied to events that reduce the blood flow to the brain through either a blocked or burst artery. This leads to the death of brain cells due to a lack of oxygen and nutrients from a lack of blood supply. The impact of stroke differs according to where the damage to the brain occurs. Stoke can occur at any age (including children) but is more common in older adults, particularly men.

Stroke is largely preventable with risk factors including high blood pressure, being overweight, smoking, high cholesterol, high alcohol intake and diabetes. A condition called transient ischaemic attack, in which the blood supply to the brain is blocked temporarily, is an important predictor of stroke.

Self-reported chronic conditions

Population surveys are important to understand how many people are living with chronic conditions. Chronic conditions are managed in a variety of settings including GP practices, allied health centres, other outpatient services and through self-management. This may cause hospitalisation records to underestimate the prevalence of these conditions. Conversely, some chronic conditions that must be treated in hospital, such as some cancer treatments, or require multiple courses of treatment, may overestimate prevalence of some conditions. Using multiple information sources provides a more complete picture.

Selected chronic conditions

A subset of chronic conditions was included on the National Health Survey (NHS) since 2001 (arthritis, asthma, back problems, cancer, COPD, diabetes, kidney disease, mental and behavioural conditions, osteoporosis, and heart, stroke and vascular disease). The 2017–18 NHS is the most recent information using consistent data collection methods for these selected chronic conditions.

Chronic conditions are a significant cause of both morbidity and mortality and in 2020, nearly 90% of all deaths were associated with one of those ten selected chronic conditions nationally.⁵ In 2017–18, for people 15 years and older:

• about 1-in-4 Queenslanders were living with one chronic condition (standardised prevalence 26.8%)
• about 1-in-5 were living with more than one of these conditions (standardised prevalence 20.0%)—known as being multimorbid.⁶

Selected chronic conditions trends in people 15 years and older from 2001 to 2017–18 showed (Figure 1):

• The standardised prevalence of back pain declined from about 23% to 13% from 2001 to 2011–12, however, rose again to 16% in 2014–15 and did not change in 2017–18.⁷
• The standardised prevalence of arthritis declined from 14% to 12% over the same period.

Hospitalisations

Remoteness and sociodemographic differences

Hospitalisation rates for people living in remote and more disadvantaged areas are higher for some conditions.

In 2020–21, standardised hospitalisation rates were higher in remote areas compared to major cities for the following conditions:

• 45.7% for asthma (1.7 compared to 1.1 per 1,000 persons, respectively)
• 2.9 times for COPD (5.2 compared to 1.8 per 1,000 persons, respectively)
• 2.8 times for diabetes (5.5 compared to 2.0 per 1,000 persons, respectively)
• 74.0% for CHD (8.8 compared to 5.1 per 1,000 persons, respectively)
• 68.3% for stroke (3.8 compared to 2.3 per 1,000 persons, respectively)
• 76.1% for the 7 lifestyle-related chronic conditions (33.5 compared to 19.0 per 1,000 persons 15 years and older, respectively).

In 2020–21, the hospitalisation standardised rates were higher in the most disadvantaged areas compared to the most advantaged areas for the following conditions:

• 70.4% for asthma (1.5 compared to 0.9 per 1,000 persons, respectively)
• 3.0 times for COPD (3.3 compared to 1.1 per 1,000 persons, respectively)
• 2.9 times for diabetes (3.9 compared to 1.4 per 1,000 persons, respectively)
• 42.4% for CHD (6.9 compared to 4.8 per 1,000 persons, respectively)
• 54.8% for stroke (2.9 compared to 1.9 per 1,000 persons, respectively)
• 53.0% for the 7 lifestyle-related chronic conditions (25.9 compared to 17.0 per 1,000 persons 15 years and older, respectively).

Trend

In Australia and Queensland, hospitalisation rates for circulatory conditions, such as CHD, have declined over the last two decades. In 2002–03, the standardised hospitalisation rate for CHD was 8.8 per 1,000 persons compared to 5.7 per 1,000 persons in 2020–21.

The gap in COPD standardised hospitalisation rates between males and females narrowed—male rates were 1.7 times higher than females in 2002–03, reducing to 1.1 times in 2020–21.

Although diabetes in Australia has increased during those time periods,⁹ hospitalisation rates for diabetes have fluctuated over the years. This is largely due to the changes in the Australian Coding Standards over the last decade, especially those that into came effect in July 2010 (7th edition).^10,11 While this makes interpreting diabetes trends more challenging, over the past decade hospitalisation rates have slowly increased.

Mortality

Demographic differences

Mortality rates varied by sex and age. For the selected chronic conditions in this section in 2020:

• Mortality rates were higher in males than females for COPD (40.8% higher), diabetes (94.4% higher), CHD (90.7% higher) and lifestyle-related chronic conditions (31.7% higher).
• Diabetes and CHD were higher in males than females for most age groups. In those 80 years and older, age-specific rates for diabetes were 49.5% higher (284.1 compared to 190.1 per 100,000 males and females, respectively) and for CHD were 28.0% higher (1067.0 compared to 833.8 per 100,000 males and females, respectively).
• Rates for stroke were similar between males and females but at age 80 years and older, the rate in women was 27.6% higher than males (693.0 compared to 543.1 per 100,000, respectively).

Remoteness and sociodemographic differences

Chronic disease mortality often varies geographically which may be due to factors such as differences in access to healthcare that may delay diagnosis or disrupt treatment, or the effects of modifiable risk factors such as obesity and smoking that may be higher in some subgroups.

Generally, people living in more remote areas or lower socioeconomic areas had higher mortality rates from the selected chronic conditions in this section.

In 2020, Queensland standardised mortality rates were higher in remote areas compared to major cities for the following conditions:

• 46.6% higher for CHD (68.0 compared to 46.4 per 100,000 persons, respectively)
• 2.8 times higher for diabetes (36.5 compared to 12.9 per 100,000 persons, respectively)
• 41.9% higher for 7 lifestyle-related chronic conditions (269.9 compared to 190.3 per 100,000 persons 15 years and older, respectively).

In 2020, Queensland standardised mortality rates were higher in the most disadvantaged areas compared to the most advantaged areas for the following conditions:

• 2.7 times for COPD (27.5 compared to 10.2 per 100,000 persons, respectively)
• 2.3 times higher for diabetes (22.0 compared to 9.7 per 100,000 persons, respectively)
• 47.6% higher for CHD (60.4 compared to 40.9 per 100,000 persons, respectively)
• 34.0% higher for stroke (33.2 compared to 24.8 per 100,000 persons, respectively)
• 62.9% higher for the 7 lifestyle-related chronic conditions (258.6 compared to 158.8 per 100,000 persons 15 years and older, respectively).

Trends

Reductions in deaths from circulatory conditions, such as CHD and stroke, are a contributing factor to declines in overall Queensland mortality rates. From 2002 to 2020, declines in standardised mortality rates were:

• CHD—145.5 per 100,000 persons to 49.6 per 100,000 persons
• stroke—66.7 per 100,000 persons to 27.2 per 100,000 persons.¹²

Burden of disease

Reductions in mortality for CHD and stroke and a reduction in hospitalisations for CHD translated to improvements in health burden. From 2003 to 2022, the standardised total burden rate for CHD decreased by 57.0%. Reductions occurred in standardised rates for both disability burden (47.8% decrease) and premature death (59% decreased). Similar improvements were seen for stroke (51.4% decrease in total burden) but gains were higher for premature death (54.4% decrease) than for disability burden (23.1% decrease).

Smaller but important gains were made for standardised rates of total burden for COPD (10.7% decrease), however, asthma saw a 7.8% increase. Negligible gains were seen for type 2 diabetes (0.5% decrease), with improvements in premature death (25.6% decrease) offset by an increase in disability burden (25.8% increase).

Most of the chronic disease health burden occurs in older age groups (Figure 8). Nevertheless, understanding differences in the age and sex profile in terms of chronic disease burden highlights potential intervention points. For example, asthma impacted all age groups throughout the life course whereas standardised rates for type 2 diabetes rapidly increased from the mid-40s, especially in males.