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Mortality and Morbidity: Living with Asthma
HOW COMMON IS ASTHMA?
In 2001, 12% of the Australian population reported they had current asthma. Asthma was more prevalent among children and young adults aged 0-19 years (14%) than among people aged 20 years and over (11%). Boys were more likely to have current asthma than girls (15% of boys aged 0-14 years, and 12% of girls of that age), and it peaked at a much earlier age for boys (5-9 years) than for girls (15-19 years). However, although prevalence of current asthma decreased with age for both men and women, women were more likely to report having asthma than men in each age group from the age of 20 years.
Indigenous people were more likely than non-Indigenous peoples to report having asthma (17% compared with 12% in 2001) (SEE ENDNOTE 4). The prevalence of asthma among Indigenous children followed a similar pattern to that of the non-Indigenous population, with prevalence increasing as children near their teens. However, the patterns diverged markedly after the age of 25 years, with the prevalence of asthma increasing after this age among Indigenous peoples. Just over 20% of Indigenous peoples aged 55 years and over reported asthma as a long-term condition in 2001, compared with less than 10% of non-Indigenous peoples in this age group.
PREVALENCE OF ASTHMA - 2001
PREVALENCE OF ASTHMA AMONG INDIGENOUS AND NON-INDIGENOUS PERSONS - 2001
ASTHMA IN CHILDREN
In 2001, asthma was the most commonly reported long-term health condition for children aged 0-14 years (13%). Of those aged 0-4 years, 8% currently had asthma which had been diagnosed by a doctor or nurse, and this increased to 16% for both 5-9 year olds and 10-14 year olds.
Asthma is difficult to diagnose in children, but is commonly a cause of wheeze. For this reason, several studies have investigated the presence of wheeze among children. In 1997, 27% of Australian children aged 0-14 years were reported to have had wheeze in the past twelve months (SEE ENDNOTE 5).
The prevalence of wheeze among Australian children is also high by international standards. In a study conducted in over 30 countries across all continents, Australia had the second highest prevalence of a current wheeze among 6-7 year olds,5 and the third highest among 13-14 year olds (SEE ENDNOTE 6).
Asthma can largely be controlled by good management, under the guidance of a general medical practitioner (GP). On average, there were 16 asthma-related GP visits per 100 population per year between July 1998 and June 2002 (3% of all GP consultations over that period) (SEE ENDNOTE 1).
Asthma Action Plans (AAP) have formed part of national guidelines for the management of asthma since 1989.1 There is evidence that the use of a written AAP, in conjunction with training in self-management and regular medical reviews, improves health outcomes for people with asthma. Better outcomes include improved lung function and a reduced need for hospitalisation, urgent GP visits and additional medication (SEE ENDNOTE 1). In 2001, 12% of people with asthma reported having a standard AAP provided by a GP. Children aged 0-14 years with asthma were more likely to have a standard AAP (18%) than people aged 15 years and over with asthma (10%).
The use of medication is the most common health-related action taken by people with asthma. In 2001, 59% of people of all ages with asthma used asthma medication to prevent and/or relieve their symptoms.
There is evidence that preventers (inhaled corticosteroids) are effective in controlling the symptoms of asthma and in preventing complications (SEE ENDNOTE 1). However, in 2001, less than a third of people with asthma (31%) used preventers, while over half (51%) of people with asthma used relievers. People aged 0-39 years with asthma were almost twice as likely to use relievers (51%) as they were to use preventers (26%). The use of preventers increased markedly after the age of 40 years, with people aged 60 years and over the most likely of all age groups to use preventers.
USE OF ASTHMA MEDICATION(a) - 2001
Despite the range of ways in which people with asthma may manage their symptoms, acute asthma episodes can still result in hospitalisation. Asthma accounted for 41,000 hospital separations in 2001-02, and is one of the most common reasons for emergency department attendance and hospitalisation among children. In 2001-02, just over half (51%) of the 41,000 hospital separations with a principal diagnosis of asthma (20,900) were for children aged 0-14 years (SEE ENDNOTE 7).
While the prevalence of asthma increases as children move into their teens, hospitalisation for asthma is highest among much younger children (aged 0-4 years), and steadily decreases over the life cycle. The reasons for the disparity between asthma prevalence and the rate of hospitalisation of very young children are not known, but are likely to reflect a range of complex issues.
Consistent with asthma prevalence, boys are more likely to be admitted to hospital for asthma than girls, while, from late teens, women are more likely than men to be admitted to hospital for asthma.
HOSPITAL SEPARATIONS FOR ASTHMA - 2001-02...VACCINATION
There is no evidence that respiratory infections directly cause the development of asthma. However, it is well established that respiratory infections can worsen asthma symptoms by acting as triggers for an attack. In 2001, people aged 50 years and over with asthma were more likely to have had an influenza (65%), or pneumococcus (24%), vaccination than people without asthma (45% and 13% respectively).
Human breast milk is recognized as having many beneficial health effects. The NHMRC recommends exclusive breastfeeding to around six months of age, and breastfeeding with appropriate complementary foods is encouraged up to at least 12 months of age (SEE ENDNOTE 8). Research has indicated that breastfeeding appears to be protective against the development of asthma and wheezes in children, (SEE ENDNOTE 9) although a recent longitudinal study does not appear to support this (SEE ENDNOTE 10). In 2001, by age six months, around half (48%) of all children were being breastfed (SEE ENDNOTE 8).
QUALITY OF LIFE
People with asthma can experience a reduced quality of life and be restricted in their daily activities. In 2001, people aged five years and over with asthma were more likely to report that they had experienced days where they had to reduce their usual activities (18%), than people without asthma (11%). Adults with asthma were also more likely to rate their health as poor or fair (28%) than people without asthma (17%), and less likely to rate their health as good, very good or excellent (72% compared with 83%).
While the number of deaths of children caused by asthma is very low, asthma can affect and disrupt children’s lives in a range of ways. Asthma is a major cause of school absenteeism, and children aged 5-14 years who had asthma were more likely to have had a day away from study in the previous two weeks (24%) than children in the same age group who did not have asthma (16%).
1 Australian Centre for Asthma Monitoring 2003, Asthma in Australia 2003, Cat. No. ACM1, AIHW, Canberra.
2 Australian Institute of Health and Welfare (AIHW) 2002, Australia's Children 2002, AIHW Cat. No. PHE 36, Canberra.
3 Australian Institute of Health and Welfare 2003, Australian long term trends in mortality workbooks, AIHW, Canberra.
4 Australian Bureau of Statistics 2003, The Health and Welfare of Australia's Aboriginal and Torres Strait Islander Peoples, cat. no. 4704.0, ABS, Canberra.
5 Woolcock, A et al. 2001, ‘The burden of asthma in Australia’ Medical Journal of Australia, vol.175, pp. 141-145.
6 Beasley, R, Keil, U, Von Mutius, E et al. 1998, ‘World wide variation in the prevalence of symptoms of asthma, allergic rhinoconjunctivitis and atopic eczema: ISAAC’, The Lancet, vol. 351, pp. 1125-1132.
7 Australian Institute of Health and Welfare 2003, National Hospital Morbidity Database, AIHW, Canberra.
8 Australian Bureau of Statistics 2003, Breastfeeding in Australia, cat. no. 4810.0.55.001, ABS, Canberra.
9 Dell, S and To, T 2001, Breastfeeding and Asthma in Young Children.
10 Sears, M, Greene, L, Willan, A, Taylor, D, Flannery, E, Cowan, O et al. 2002, ‘Long-term relation between breastfeeding and development of atopy and asthma in children and young adults: a longitudinal study’, TheLancet, vol. 360, pp. 901-907.