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By Christine Jenkins, MD, FRACP Biographical note
Introduction
Asthma is a disorder affecting the air passages of the lung. People with asthma have very sensitive airways that narrow in response to certain triggers, leading to difficulty in breathing. The airway narrowing is caused by inflammation and swelling of the airway lining, tightening of the airway muscles, and the production of excess mucus. This results in a reduced airflow in and out of the lungs.
Asthma is one of Australia’s most widespread chronic (long term and persistent) health problems, affecting up to 14% of children and 10–12% of adults. These rates are high by international standards. At present the cause of asthma is not known and there is no cure.
However, asthma is treatable: medications, asthma management and education are improving all the time. With appropriate treatment and a personal commitment to good self-management, most people with asthma can lead normal, active lives. Indeed, many are high-achieving sportspeople.
The following websites contain information on asthma:
Asthma prevalence in Australia
Over 2 million Australians have asthma: 1 in 7 primary school-aged children, 1 in 8 teenagers and 1 in 9 adults. In primary school-aged children, asthma is slightly more common among boys than among girls, but after the teenage years, more women have asthma than men.
The prevalence of asthma in Australia increased through the 1980s and 1990s, especially in children, but the latest evidence suggests there has been no further increase in recent years and this trend may even be reversing in children. However, the prevalence of asthma in Australia is still high compared with other countries.
Among children aged 13–14, Australia has the third highest worldwide rate of current wheeze in (after the UK and New Zealand). Whereas studies undertaken in the late 1990s found that only a small proportion of Australian children with frequent wheeze were taking regular preventer medication, more recent studies show there has been an improvement. Increased uptake of effective medications is probably an important reason why emergency department visits and intensive care admissions have decreased. A wider understanding of the potential dangers of acute asthma and the appropriate response to warning signs of a severe attack have probably also played a role.
Asthma is one of the most common reasons for hospital admission and emergency department visits in children, but this has decreased as asthma education has improved, and as effective medications have become available and have been used by more children. Asthma-related visits to hospital or GPs are most common among the pre-school age group. In pre-school aged children and primary aged children, the peak time for hospital visits for asthma is in February, soon after school goes back.
Australia’s death rate from asthma has steadily fallen since the early 1990s and over the last 3–4 years there have been around 300 deaths per year. The majority of these deaths occur in people over 55 years, and the recognition, accurate assessment and optimal management of asthma in this older group of adults is still a challenge.
Demographic differences
While there are some geographical differences in asthma prevalence within Australia, there are no large discrepancies between or within the states and territories. Regional variations in the prevalence and severity of childhood asthma were found in one NSW study. The authors suggest these variations could relate to different levels of sensitisation to common allergens such as house dust mite (higher in coastal areas) and alternaria, a mould found on agricultural crops (higher in inland areas). Summer storms that occur in inland regions are associated with sudden falls in barometric pressure and rupture of pollen grains. These tiny grass pollen fragments may be inhaled, causing mini-epidemics of “thunderstorm asthma” in allergic people. In general, however, there is no marked difference between urban and rural settings in Australia.
Asthma is more common among Indigenous Australians, particularly adults, than among other Australians. Asthma is less common among Australians who were born in non-English-speaking countries than among other Australians, but may be more severe when it occurs in older adults from these groups. Hospitalisation rates for asthma are higher among Aboriginal and Torres Strait Islander Australians and among people living in remote and less economically advantaged areas.
The worldwide picture
Australia has one of the highest rates of asthma prevalence in the world, along with New Zealand and the UK. There is a wide variation in asthma incidence worldwide, and it is the highly developed, less polluted Western countries that have the highest rates of asthma. Contrary to popular belief, the global pattern of prevalence shows that air pollution is not a major risk factor for developing asthma. Rather, it is a trigger for symptoms in some people with asthma. Several early life factors may reduce the risk of developing asthma – these include attendance at day care, exposure to animals in the home, having older siblings, living on a farm and absence of early exposure to antibiotics.
The wide variations in asthma prevalence may point to other environmental factors: changes in housing and furnishings allowing higher levels of allergens such as house dust mites, indoor pollutants like passive smoking, and perhaps changes in diet. Children of mothers who smoke during pregnancy are significantly more likely to develop wheezing illnesses under the age of 3, and have a significantly increased risk of developing asthma.
Asthma mortality (deaths)
In 2005 (the latest figures available), 318 Australians died from asthma – 210 females and 108 males. This number is seven more than the number of deaths recorded in the previous year, but a substantial reduction compared with previous decades. Asthma death rates have been falling steadily, compared with 964 deaths in 1989 and 685 deaths in 1998.
Deaths from asthma are now very uncommon in children, and have decreased in younger adults. Asthma deaths are highest in older people, although there is sometimes doubt about the cause of death when other illnesses are present.
In 2005, 191 asthma deaths (60%) were in people aged 70 and older, and 95 deaths (30%) were in people aged 40 to 60. Death rates in younger age groups have remained stable and relatively low, suggesting that parents, teachers and young people are taking up messages about good asthma care.
The drop in deaths can be attributed to the sum of all asthma management, education and treatment changes over this time. These include better use of preventive medication, provision of better asthma management plans, more effective asthma reviews by GPs, improved management by doctors and hospital emergency departments, consistent advice from pharmacists and other health professionals, increased more effective services by community organisations such as the Asthma Foundations, and a greater awareness of asthma, meaning people are getting help earlier.
Up to 60% of asthma deaths may be associated with avoidable factors and death from asthma is preventable in many cases. Risk factors for dying from asthma include a previous life-threatening episode, over-reliance on reliever medications, delay in seeking help, failure to recognise the severity of asthma and lack of regular medical review.
Asthma and quality of life
More than 60% of people with asthma experience night-time symptoms at some time. These include shortness of breath, chest tightness, wheezing or coughing. Waking at night with asthma symptoms is a sign of poorly controlled and under-managed asthma. It is a treatable problem and is a sign that asthma is unstable and requires more preventive medication.
A majority of people with asthma have symptoms triggered by vigorous exercise. Exercise-induced asthma (EIA) may be the only symptom of asthma in some people, but it may also indicate under-treated asthma. Exercise is beneficial to health and wellbeing, and EIA can be successfully prevented with the right treatment.
Up to 80% of people with asthma also suffer from allergic rhinitis (inflammation of the nose lining), and around 30% of people with allergic rhinitis have asthma. This is thought to be due to the common genetic basis that predisposes people to both conditions. Good treatment is available for these conditions.
Despite the fact that smoking is especially risky for people with asthma, smoking rates are as high among people with asthma as in those without. As well as being a trigger for asthma symptoms, smoking may accelerate the loss of lung function that can occur in under-treated asthma. Smoking also contributes to other lung diseases and to the development of asthma in children exposed to tobacco smoke. Smoking has also been shown to reduce the effectiveness of inhaled corticosteroids, which are the most effective preventive medications.
Among people with asthma, smoking is most common among young adults and those who live in economically disadvantaged areas. About 40% of Australian children who have asthma live with smokers. Among the indigenous population, smoking prevalence is very high, around 50% of indigenous adults being current smokers. The high rate of smoking in pregnant women is of particular concern as it increases the risk of developing asthma in children.
Asthma is often under-managed, and is a major cause of hospital admission among children and of absence from school. Work absenteeism among adults with asthma is another large-scale problem. Asthma ranks among the ten most common reasons for seeing a GP.
However, when asthma is well managed, the quality of life of people with asthma is high. Many well-known Australians have asthma, including prominent athletes, singers, dancers and others whose good health and fitness is essential to their careers.
The cost of asthma to the community
Direct health expenditure on asthma – the cost of pharmaceutical prescriptions and devices, medical consultations and hospital services – is approximately $700 million per year, based on the most recent financial data (for the 2000–2001 financial year). More than half of direct costs are for medications, and direct health expenditure for asthma is highest for children.
Between 1993–94 and 2000–01 (adjusted for inflation), per capita health expenditure on asthma increased by 21%. Overall health expenditure increased by 26% in the same period.
Asthma also costs our community additional indirect costs – those incurred by people with asthma and their families or by the community, which include the costs of absence from work and social activities, and lost productivity at work.
People with severe asthma and those with poorly controlled asthma (people who are not appropriately or adequately treated, or who do not take their medications) have much higher medical costs, usage of the healthcare system and time away from school or work than those with the same severity of disease who have well-controlled asthma.
Researchers estimate that 45% of these costs could be saved if optimal asthma control were achieved for all people with severe asthma. Not only is this a significant saving to the community, but there would be a great improvement in the individual’s quality of life and/or productivity.
In 1999, asthma was declared a National Health Priority and a wide range of initiatives have been funded to improve diagnosis, management and outcomes. New programs have been undertaken in asthma education and management, including the Asthma Friendly Schools program, community education programs and improvements in emergency management and follow-up from hospital. The Australian Centre for Asthma Monitoring (ACAM) was established in 2002 as an activity associated with the recognition of asthma as a National Health Priority Area. It enables accurate, up-to-date records and publications of the impact, social and capital costs of asthma on Australians.
A major program, the Asthma Cycle of Care, is underway to encourage and assist general practitioners to manage asthma more effectively. The Asthma Cycle of Care involves assessment of asthma severity, regular medical review, self-management education and provision of a written asthma action plan for patients with a recent hospital admission, moderate to severe asthma or newly diagnosed asthma. This is an innovative evidence-based program that is expected to enhance asthma care and improve outcomes for people with asthma.
Reviewed and updated April 2007
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