Asthma is a chronic inflammatory disorder of the airways. In susceptible individuals this inflammation causes recurrent episodes of wheezing, breathlessness, chest tightness and coughing, particularly at night or in the early morning (AIHW 2003). Asthma was identified as the sixth National Health Priority Area in 1999. Unless otherwise stated this article presents information sourced from the 2001 ABS National Health Survey (NHS).
- The prevalence of asthma is based on people reporting that they had been diagnosed with asthma by a doctor or nurse, and that the asthma was a current condition.
- According to the 2001 NHS, 12% of Australians (2.2 million people) reported they currently had asthma, an increase on the 8% prevalence in 1989-90. This increase may be the result of a number of factors including actual increased prevalence of asthma and heightened awareness of this condition.
DIFFERENTIALS IN PREVALENCE
AGE AND SEX
- Asthma was more prevalent among children and young adults aged 0-19 years (14%) than among people aged 20 years and over (11%).
- Asthma is the most commonly reported long-term condition for children aged 0-14 years (13%).
- Boys aged 0-14 years were more likely to have asthma than girls of the same age group (15% compared with 12%).
- Asthma prevalence peaked at a much earlier age for boys (5-9 years) than for girls (15-19 years).
- After age 20 years, women were more likely than men to report having asthma (12% of women compared with 9% of men).
Prevalence of asthma, 2001
- After adjusting for age differences, Indigenous Australians were more likely to report asthma than the non-Indigenous population (17% compared with 12%).
- The pattern of prevalence was similar for non-Indigenous and Indigenous people aged 0-34 years.
- In 2001, 21% of Indigenous people aged 55 years and over reported asthma compared with 9% of non-Indigenous people in the same age group (ABS 2003).
Prevalence of asthma among indigenous Australians, 2001
COUNTRY OF BIRTH
- In 2001, asthma prevalence was lower in people born overseas (8%) than those born in Australia (13%).
- Rates were also higher among those born in New Zealand (12%) and United Kingdom (9%) than in those born in North Africa and the Middle East (5%) and South East Asia (5%). This is consistent with previous findings that asthma prevalence is higher among children and adults born in Australia than those who were born overseas and migrated to Australia (AIHW 2003).
- Asthma prevalence has been found to increase among migrant populations with increase in duration of residence (Leung et al. 1994).
PREDISPOSING, CONTRIBUTING AND PROTECTIVE FACTORS
- There is increasing evidence that asthma is induced prenatally in genetically predisposed children. Allergen exposure, chemical sensitisers and diet are triggers of asthma (NIH 1995).
- Other contributing factors include viral infections, small size at birth, tobacco smoking, and environmental pollutants (NIH 1995).
- Although not definitive, research suggests that infant breastfeeding practices may have an effect on the development of asthma or wheeze in children younger than 2 years. The positive effect of breastfeeding appears to be stronger with the length of time the infant is breastfed (suggesting a dose-response effect) (Dell & To 2001).
- There was an increase of 9% in the number of infants under one month being breastfed in 2001 (91%) when compared to estimates obtained from the 1995 NHS (82%). Generally, the rate of breastfeeding for infants at all age groups under 12 months has increased from those estimates derived from the 1995 NHS (51% infants under 12 months were currently breastfed in 2001 compared with 45% in 1995).
- In 2001, 59% of people with asthma used pharmaceutical medications to prevent and/or relieve their asthma symptoms.
- Research has shown that preventers (inhaled corticosteroids) are effective in controlling the symptoms of asthma and in preventing complications (Rowe et al. 2000). However in 2001, only 31% of asthmatics used preventers, while 51% used relievers.
- Asthma action plans (AAP) have formed part of national guidelines for the management of asthma since 1989 (National Asthma Campaign 1998). In 2001, only 12% of people with asthma reported having a standard AAP. Children aged 0-14 years with asthma were more likely to have a standard AAP (18%) than adults with asthma (9%).
- In 2001-02 asthma accounted for 41,000 hospital separations. Children aged 0-14 years accounted for 51% of these (AIHW 2003).
- Asthma is the most common reason for emergency department attendance and hospitalisation among children (AIHW 2003).
- Consistent with asthma prevalence, boys are more likely to be admitted to hospital for asthma than girls. However from late teens, women were more likely than men to be admitted to hospital for asthma.
QUALITY OF LIFE
- In 2001, 18% of people with asthma reported having days of reduced activity compared with only 10% of people without asthma. They were also more likely to report having days away from work or study (11% compared with 8%).
- Adults with asthma were more likely to rate their health as being poor (8%) than people without asthma (4%), and less likely to report their health as excellent (11% compared with 20%).
- In 2002, there were 397 deaths where the category asthma and status asthmaticus (acute severe asthma) was identified as the underlying cause (158 males and 239 females), accounting for 0.3% of all deaths in that year.
- Death rates for asthma have declined over the recent decade. In 1992, the age standardised death rate for asthma was 5.0 per 100,000 persons compared with 2.0 per 100,000 persons in 2002 (ABS 2003).
- Although the risk of dying from asthma is low, this risk increases with age. The majority of deaths from asthma occurred in people aged 65 years and over.
Australian Bureau of Statistics 2003, The Health and Welfare of Australia's Aboriginal and Torres Strait Islander Peoples, cat. no. 4704.0, ABS, Canberra.
Australian Bureau of Statistics 2003, Cause of Death, Australia, cat. no. 3303.0, ABS, Canberra.
Australian Institute of Health and Welfare 2003, Asthma in Australia 2003. AIHW Cat. No. CAM1, Canberra.
Australian Institute of Health and Welfare 2003, National Hospital Morbidity Database, AIHW, Canberra.
Dell, S. and To, T. 2001, Breastfeeding and asthma in young children, Arch Pediatr Adolesc Med,155, (Nov 2001):1261-65.
Landau, L. 2002, Definitions and early natural history, Medical Journal of Australia, 77, (16 September): 38- 41.
Leung, R., Carlin, J.B., Burdon, J.G.W., & Czarny, D. 1994, Asthma allergy and atopy in Asian immigrants in Melbourne. Medical Journal of Australia, 161, (3 October): 418-25.
National Asthma Campaign 1998, Asthma management handbook: revised and updated, National Asthma Campaign LTD, Melbourne.
NIH 1995, Global strategy for asthma management and prevention NHLBI/WHO workshop. National heart, lung and blood institute, 95-3659.
Rowe, B. et al. 2000, Corticosteroids for preventing relapse following acute exacerbations of asthma, The Cochrane Library, Oxford.