Asthma: The Basic Facts

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Asthma in Australia

Over 2.2 million Australians have currently diagnosed asthma.1
The prevalence of asthma in Australia is relatively high, by international standards:1
- 14-16% of children (one in six)
- 10-12% of adults (one in nine)
More boys than girls have asthma. However, after teenage years, asthma is more common in women than in men.1 
Asthma is more common among Indigenous Australians, particularly adults, than among other Australians.1  
There is a strong link between asthma and allergy: more than 80% of people with asthma have evidence of allergic sensitisation.2 
Atopy is strongly associated with asthma that persists beyond the first 6 years of life.3,4  
The presence of other allergic disorders (eczema or allergic rhinitis) or parental history of atopy are risk factors for persistent asthma at 6 years.5  
Atopy is also a risk factor for hospitalisation for asthma, as are frequent respiratory symptoms, airway hyperresponsiveness and reduced lung function.6
Children aged 0 to 4 years are the group that most commonly visits general practitioners or emergency departments or is hospitalised for asthma.1 
Among pre-school and primary age children, rates of hospital visits for asthma are highest in February.1 
Around 40% of children who have asthma live with smokers and are likely to be exposed to passive smoke.1
Despite the known additional health risks, just as many people with asthma smoke as people without asthma .1 
People with asthma report poorer general health and quality of life than people without asthma.1
More people with asthma suffer from anxiety and depression than people without asthma.1
A greater proportion of people with asthma had days away from work or study in the last two weeks (11.4%) than people without asthma (7.9%) preceding a survey.1 
Poorly controlled asthma restricts participation in normal physical and social activities.7  
The risk of dying from asthma is highest in the elderly; however, asthma deaths occur in all age groups.1  
In 2005, 318 people died from asthma - the latest figures.8
Asthma deaths are more common among those living in less well-off localities in Australia.1  
However, education, together with self-monitoring, appropriate drug therapy, regular medical review and an written asthma action plan, reduces morbidity and mortality.7,9  
Most people with asthma lead normal lives and can participate competitively in sport. Many of Australia's leading sportsmen and women have asthma.7  

Definition of Asthma

Asthma is a chronic inflammatory disorder of the airways in which many cells and cellular elements play a role, in particular, mast cells, eosinophils, T lymphocytes, macrophages, neutrophils, and epithelial cells. In susceptible individuals, this inflammation causes recurrent episodes of wheezing, breathlessness, chest tightness, and coughing, particularly at night or in the early morning. These episodes are usually associated with widespread but variable airflow obstruction that is often reversible either spontaneously or with treatment. The inflammation also causes an associated increase in the existing bronchial hyperresponsiveness to a variety of stimuli.10

Airflow obstruction (excessive airway narrowing) in asthma is the result of contraction of the airway smooth muscle and swelling of the airway wall due to:

  • smooth muscle hypertrophy and hyperplasia
  • inflammatory cell infiltration
  • oedema
  • goblet cell and mucous gland hyperplasia
  • mucus hypersecretion
  • protein deposition including collagen
  • epithelial desquamation.

This inflammatory process can cause permanent changes in the airways. Long-term changes include increased smooth muscle, increase in bronchial blood vessels, thickening of collagen layers and loss of normal distensibility of the airway.

Potential triggers for the inflammatory process in asthma include allergy, viral respiratory infections, gastro-oesophageal reflux (GORD), irritants such as tobacco smoke, air pollutants and occupational dusts, gases and chemicals, certain drugs, and non-specific stimuli such as cold air exposure and exercise.

Education of people with asthma about the nature of the disease - that it is more than bronchospasm, and is an inflammatory disease - helps them gain a greater understanding of the need for separate types of medication for asthma management:

  • bronchodilator (also referred to as reliever) medication
  • anti-inflammatory (also referred to as preventer) medication
  • long-acting beta2 agonist (also known as symptom controller) medication usually prescribed in combination with an inhaled corticosteroid (ICS) preventer. Combination medications consist of an ICS and a symptom controller in a single inhaler device.

In addition, education about other measures to improve asthma control is important:

  • allergen avoidance/control
  • use of a written asthma action plan
  • smoking cessation, diet and exercise (including specific management of exercise-induced asthma if required).