Asthma in Australia 2005 
Table of Contents | Chapter  1   2   3   4   5   6   7   8   9  | Appendix   1   2   | References |

5 Use of health services | Introduction | 5.1 General practice encounters | 5.2 Hospital emergency department visits | 5.3 Hospitalisations | 5.4 Invasive mechanical ventilation | 5.5 Re-attendances for asthma |

5.3 Hospitalisations
Introduction | Time trends in hospital use for asthma | Differentials in hospital use for asthma | Summary |

Key points

• Children, particularly those aged less than 5 years, have higher rates of hospitalisation for asthma than adults.
• There was a 43% reduction in the rate of hospital admissions for asthma among children and a 17% reduction among adults between 1993–94 and 2003–04.
• The average length of stay for people hospitalised for asthma fell from 2.9 days to 2.2 days between 1993–94 and 2003–04.
• The total hospital bed-days occupied by people with asthma decreased by 49% between 1993–94 and 2003–04.
• Among people aged 65 years and over, rates of hospitalisation for asthma are highest in the winter months, whereas, among children, the peaks occur in February and May.
• Among children, boys have higher rates of hospitalisation for asthma than girls, in keeping with the higher prevalence of asthma in boys. However, this trend is reversed after the age of 15 years when more females than males are admitted to hospital for asthma.
• Among people aged 35 years and over, rates of hospitalisation for asthma are higher in people living in more remote areas.
• Indigenous Australians have higher rates of hospitalisation for asthma than other Australians in all age groups.
• Rates of hospitalisation for asthma are higher among people living in more socioeconomically disadvantaged areas.

Hospitalisation for asthma occurs as a consequence of disease exacerbations. Hospitalisation is required when the exacerbation is severely disabling or life-threatening or when other circumstances make home-based management inadvisable or not feasible.

Changes in the number of hospitalisations for asthma may be due to changes in the severity and prevalence of the disease in the community and the effectiveness of disease management (Adams et al. 2000; Christakis et al. 2001; Griffiths et al. 1997; Homer et al. 1996; Jalaludin et al. 1998; Rasmussen et al. 2002). The use of hospital care for the management of exacerbations may also be influenced by the relative accessibility of hospital services and of alternative services such as general practitioners, especially after hours (Phelan et al. 1993, 2002). Changes in admission criteria and administrative policies will also affect hospital usage data.

The data for this section are derived from the National Hospital Morbidity Database (NHMD) (AIHW) for the period 1993–94 to 2002–03. In these data, the term ‘hospital separation’ refers to the formal process by which a hospital records the completion of treatment and/or care for an admitted patient. This includes completion due to discharge, death, transfer to another hospital or change in the type of care. For more information on this database, see Appendix 1, Section A1.9. A summary of these data is provided in Appendix 2, Tables A2.7, A2.8 and A2.9.

In 2003–04, hospital separations with a principal diagnosis of asthma accounted for 37,989 or 0.6% of all separations (AIHW 2005).

Time trends in hospital use for asthma

There has been an overall reduction in the rate of hospital separations for asthma among children, especially those aged 0 to 4 years and 5 to 14 years, since 1993. Much of the decline in the 0 to 4 years age group occurred since 1996. The hospitalisation rate in people aged over 15 years was much lower but also decreased overall during this time (Figure 5.20). Between 1993–94 and 2003–04, hospital separations decreased by 43% among children aged 0 to 14 years and by 17% among those aged 15 years and over. Among adults, most of this decline has occurred since 1998–99. The trends in hospital separation rates are unchanged by the exclusion of same day separations (i.e. people who were discharged on the same day as they were admitted (data not shown)).

Figure 5.20: Hospital separations for asthma per 100,000 population, by age group, Australia, 1993–2005

The average length of stay in hospital among people admitted with asthma decreased from 2.9 days in 1993–94 to 2.2 days in 2003–04. This trend toward shorter stays has been observed in all age groups (Figure 5. 21).

Figure 5.21: Average length of stay for asthma, by age group, Australia, 1993–2004

The trend towards a reduction in the number of hospital separations for asthma, together with a reduction in the length of stay associated with those separations, has resulted in an even larger reduction in the total number of patient days in hospital attributable to asthma (Figure 5.22). The overall number of hospital bed-days occupied by patients with asthma has declined by 49% between 1993–94 and 2003–04.

Figure 5.22: Hospital patient days for asthma per 100,000 population, by age group, Australia, 1993–2004

Seasonal variation in hospital use for asthma

Several studies conducted overseas have shown that hospitalisation rates for asthma are higher during winter months in the older age groups, and higher in late summer and autumn among children and young adults (Fleming et al. 2000; Gergen et al. 2002; Harju et al. 1998; Kimbell-Dunn et al. 2000).

Data for Australia (Figure 5.23) reflect a similar pattern, with highest separation rates over winter in adults, most notably in people aged 35 years and over. This seasonal pattern is likely to reflect the impact of the winter rise in respiratory tract infections.

Figure 5.23: Seasonal variation in hospital separation rates for asthma, by age group, Australia, 1993–2003

Differentials in hospital use for asthma

Age and sex

Children aged 0 to 4 years had the highest rate of hospital separations for asthma in 2002–03 and the rate among boys in this age group was almost twice that of girls (Figure 5.24). Boys aged 5 to 14 years also had a higher rate of hospital separations for asthma than girls. This pattern was reversed in people aged 15 years and over, with females having a higher rate than males.

Figure 5.24: Hospital separations for asthma per 100,000 population, by age group and sex, Australia, 2002–03

The gender differences in hospitalisation rates are partially explained by differences in disease prevalence. In Figure 5.25, hospitalisations for asthma have been expressed as a rate per 100 people with current asthma, as estimated by the National Health Survey 2001, for each age and gender group. Boys aged 0 to 4 years with asthma were more likely to be hospitalised than girls of the same age with asthma but the difference between boys and girls aged 5 to 14 years with asthma was minimal. Gender differences in hospitalisation rates in other age groups were relatively minor, except among the elderly where females with asthma were more likely to be hospitalised than males.

However, the age differential in hospital separation rates is not explained by differences in prevalence. The case-based hospitalisation rates were much higher for children, especially those aged 0 to 4 years, than for adults.

Figure 5.25: Hospital separations for asthma per 100 people with asthma, by broad age group and sex, Australia, 2002–03

Average length of stay for people hospitalised with asthma increased with age (Figure 5.26). The median length of stay (length of hospital stay for 50% of people) for asthma separations during 2002–03 was 1–2 days among 0 to 14 year olds compared to 3–5 days for people aged 65 years and over. Among persons aged 5 years and over, females had a slightly longer length of stay than males (data not shown).

Figure 5.26: Relative frequency of length of stay for asthma, by broad age group, Australia, 2002–03

States and territories

Hospital separation rates for asthma in 2002–03 were lower than the national average in Victoria, Tasmania and the Australian Capital Territory and were higher than average in Western Australia and South Australia. These differences between jurisdictions are mainly attributable to differences in hospital separation rates for children, particularly those aged 0 to 4 years, but also to a lesser extent those aged 5 to 14 years (Figure 5.27).

Figure 5.27: Hospital separations for asthma per 100,000 population, by age group, state and territory, Australia, 2002–03

Urban, rural and remote areas

Hospital separation rates for asthma generally increased, particularly for adults, with increasing remoteness from major cities (p<0.001; Figure 5.28). This trend was independent of related variation in socioeconomic disadvantage (SEIFA) and was steeper with increasing age. The difference in hospital separation rates for asthma between people living in major cites and those living in remote and very remote areas was 32%, 70%, 160% and 220%, in the age groups 5 to 14, 15 to 34, 35 to 64 and 65 years and over, respectively . However, among children aged 0 to 4 years, those living in major cities had the highest separation rate. This pattern was in contrast to other age groups.

These findings are broadly consistent with observations on regional variation in hospitalisation rates for all diagnoses, and with previous studies showing increased hospitalisation for asthma in rural areas (AIHW 2002a; Jones et al. 1998; Tong & Drake 1999).

Figure 5.28: Hospital separations for asthma per 100,000 population, by age group and remoteness, Australia, 2002–03

Similar age trends were observed when examining total patient days for asthma. However, the magnitude of the difference between major cities and very remote areas among people aged 65 years and over was greater than observed for hospital separations for asthma, reflecting a longer average length of stay among elderly people in remote areas (Figure 5.29).

Figure 5.29: Hospital patient days for asthma per 100,000 population, by age group and remoteness, Australia, 2002–03

Aboriginal and Torres Strait Islander Australians

Hospital separation rates for asthma were higher among Indigenous Australians than among other Australians across all age groups, but particularly among persons aged 35 years and over (Figure 5.30). Data for patient days reflected a similar pattern (Figure 5.31).

Among Indigenous Australians during childhood (0 to 14 years), hospital separations for asthma were consistently higher in males; however, after the age of 15 years this was reversed and females demonstrated higher hospital separation rates across all ages (data not shown). This gender differential, which changes with age, is consistent with observed gender differentials in hospital separation rates for asthma in the general population.

The relatively high rate of hospital separations for asthma among Indigenous Australians is consistent with the overall high rates of hospitalisation in this community in every age group and for both sexes (AIHW 2004a). In addition to this, hospitalisation rates for Aboriginal and Torres Strait Islander people are likely to be an underestimate of the true hospitalisation rates due to under enumeration of Indigenous Australians in most states and territories. Only three jurisdictions are considered reliable; Northern Territory, Western Australia and South Australia.

Figure 5.30: Hospital separations for asthma per 100,000 population, by age group and Indigenous status, Australia, 2002–03

Figure 5.31: Hospital patient days for asthma per 100,000 population, by age group and Indigenous status, Australia, 2002–03

Culturally and linguistically diverse background

Among persons aged 5 years and over, the rates of hospitalisation for asthma were higher in people from English-speaking backgrounds than in people from non-English-speaking backgrounds, consistent with the differences in prevalence (Figures 5.32 and 5.33).

Figure 5.32: Hospital separations for asthma per 100,000 population, by broad age group and English-speaking versus non-English-speaking background, people aged 5 years and over, Australia, 2002–03

Figure 5.33: Hospital patient days for asthma per 100,000 population, by broad age group and English-speaking versus non-English-speaking background, people aged 5 years and over, Australia, 2002–03

Socioeconomic disadvantage

Rates of hospitalisation for asthma were higher among people who lived in more socioeconomically disadvantaged localities than for those living in more advantaged localities (p<0.001; Figure 5.34). This trend was independent of related variation in remoteness from services (ASGC). Apart from persons aged 65 years and over, the trend did not vary substantially with age. The difference in hospital separation rates between persons who lived in locations in the most socioeconomically advantaged quintile and those who lived in locations in the two most disadvantaged quintiles was 41%, 49%, 45%, 64% and 15%, in the age groups 0 to 4 years, 5 to 14 years, 15 to 34 years, 35 to 64 years and 65 years and over, respectively. Data for patient days reflected a similar pattern (Figure 5.35).

Figure 5.34: Hospital separations for asthma per 100,000 population, by broad age group and socioeconomic status, Australia, 2002–03

Figure 5.35: Hospital patient days for asthma per 100,000 population, by broad age group and socioeconomic status, Australia, 2002–03

Summary

Since 1993, rates of hospital bed utilisation for asthma have declined substantially. However, children still have high rates of hospitalisation for asthma compared with adults.

Indigenous Australians, people living in remote areas and those living in socioeconomically disadvantaged areas have higher separation rates for asthma. These trends reflect similar trends observed for hospital separations for all causes.

Among children, boys have higher rates of hospitalisation for asthma than girls, in keeping with the higher prevalence of asthma in boys. However, among persons aged 15 years and over, hospitalisation for asthma is more common in females than males.

There is a marked seasonal variation in rates of hospitalisation for asthma. The seasonal patterns differ between age groups. There is an increased risk of hospitalisation for asthma during winter in adults, particularly those aged over 35 years. However, among children and young adults, seasonal peaks are seen in February and May. This is consistent with patterns that have been observed in studies both locally and overseas.

© Australian Institute of Health and Welfare 2005

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