Australia State of the Environment Report 2001 (Theme Report)
Lead Author: Professor Peter W. Newton, CSIRO Building, Construction and Engineering, Authors
Published by CSIRO on behalf of the Department of the Environment and Heritage, 2001
ISBN 0 643 06747 7
Liveability: human well-being (continued)
Environmental health (continued)
Quality of life is difficult to conceptualise and measure at a population level. An alternative approach to summing up the health of a population is a measure of life expectancy adjusted to take account of time lived with a disability, called 'disability adjusted life expectancy' or DALE (Murray et al. 1999). To calculate DALE, the years of ill-health are weighted according to severity and subtracted from the expected overall life expectancy to give the equivalent years of healthy life (WHO 2000). The other major measure used is DALY. The DALY measure was developed for the World Bank in 1993 to study the global burden of disease (Murray and Lopez 1996). One DALY is a lost year of 'healthy' life and is calculated as a combination of years of life lost due to premature mortality (YLL) and equivalent 'healthy' years of life lost due to disability (YLD).
Based on 1996 data, Australians have a healthy life expectancy of 73.2 years, second only to the Japanese (74.5 years). The rest of the top 10 nations are in Western Europe. Years lost to disability are substantially higher in poorer countries. People in the wealthiest regions lose about 9% of their lives to disability, compared to 14% in the poorest countries.
It has been estimated that some 2.5 million DALY were lost because of premature mortality and disability in Australia in 1996. The male disease burden in DALY terms was estimated to be 13% higher than the female disease burden, primarily due to the difference in the premature mortality burden. Males lost 26% more years of life (YLL) than females. In contrast, YLD was 1% lower for males than females. Among males, the greatest disease burden was in the 25-64 age group (43%), while among females the burden was greatest for those aged 65 years and over (47%) (Figure 65).
Figure 65: Burden of disease by age and sex, Australia, 1996.A
AYLL refers to years of life lost due to premature mortality and YLD refers to years of 'healthy' life lost due to poor health or disability.
Source: Mathers et al. (1999).
Cardiovascular disease, cancers and injury were responsible for 72% YLL in both the sexes, while mental disorders were the leading YLD causes, accounting for nearly 30% of the non-fatal burden of disease in Australia.
The leading causes of disease burden also differ by age. For example, in 1996:
- asthma was the leading cause of disease burden among children aged 0-14, accounting for over 18% of DALY in that age group;
- among Australians aged 15-24 years, alcohol dependence/harmful use and road traffic accidents were the leading causes, each accounting for over 9% of DALY in this age group, followed by depression, bipolar affective disorder, and suicide and self-inflicted injuries, which together accounted for 22% of DALY among 15-24 year olds;
- ischaemic heart disease was the leading contributor to DALY in adults aged 25-64 years, accounting for 8.5% of their total DALY, with depression as the second most common cause (6.3% of DALYs);
- ischaemic heart disease and stroke were the leading causes of diseases burden among Australians aged 65 years and over, together accounting for 32% of the total DALY.
The burden of disease also tends to increase with increasing levels of socio-economic disadvantage for both the sexes. Classifying the Australian population into quintiles, using a small-area-based index of socio-economic disadvantage (the SEIFA index of relative socio-economic disadvantage), reveals that there is a marked increase in the total burden of disease with increasing socio-economic disadvantage (see Figure 66). The differences are largest for intentional and unintentional injuries, diabetes, digestive system disorders (in males) and mental disorders (Mathers et al. 1999).
Figure 66: Estimated burden of disease and injury
Age-standardised DALYs per 1000 population among males and females, according to quintile of area of socio-economic disadvantage, 1996.
Source: Mathers et al. (1999).
A recent study of health status across Victoria (DHS 2001) using DALY, revealed significant geographic variability in outcomes. Metropolitan Melbourne residents fare best, with lowest number of years lost due to death, disease and disability.
- Australia has experienced considerable reductions in mortality rates over the past century. Death rates are now less than half what they were in the early 1900s. These declines, however, have not been the same among all population groups.
- Improvements in social and environmental conditions, such as sanitation, health education, the quality of food and water supply, and better housing contributed to the decrease in mortality in the early part of the century, particularly deaths from infectious diseases.
- At present, major causes of mortality in Australia are cardiovascular diseases, cancer, respiratory diseases and injuries, particularly motor vehicle accidents and suicide. Lifestyle and environmental factors such as smoking (including passive smoking), poor diet, physical inactivity, exposure to allergens and air pollutants, poor road quality in some areas of Australia, and the distances travelled are some of the risk factors for these causes of death.
- Although chronic, non-communicable diseases - with significant environmental input - have become more prominent, improvements have been noted on several fronts lately. These include behavioural or lifestyle changes such as decreased smoking and improved diet. Advances in medical technology including mass immunisation and antibiotics, improved medical care and the development of surgical interventions such as coronary bypass operations, are also believed to have had a significant impact on health outcomes.
- Although Australia ranks highly in comparison to other countries in terms of healthy lives, certain groups in Australia are relatively worse off. In Australia, those living in poorer social and economic conditions have worse health than those living in better social and economic conditions.
- People living in rural and remote areas of Australia tend to have higher death rates than those living in capital cities and other metropolitan areas. This may be attributed partly to the harsher living environments in more remote areas, an environment in many ways different to the metropolitan environment. Relatively poor access to health services, lower socio-economic status and employment levels, exposure to comparatively harsher environments and occupational hazards contribute to and explain some of these differentials.
- Australians living in rural and remote areas have lower access to primary care medical practitioners, specialists, pharmacists and dentists. Shortages and uneven distributions of health facilities and health professionals are compounded by access difficulties relating to distance, time, cost and transport availability in rural and remote zones.
- Improved access to health care facilities and health care professionals is critical to minimising variation in health outcomes between people living in various zones. Attempts are being made to address some of these issues through telemedicine and other initiatives proposed in the last rural health strategy.
- Indigenous Australians have a worse health status than non-Indigenous Australians. Indigenous people have not shared to the same degree in the improvements in health enjoyed by other Australians over the past century, with life expectancies 100 years behind those of non-Indigenous Australians (AIHW 2000a).
- Indigenous people are more likely than non-Indigenous people to be exposed to poor living conditions, including living in improvised or overcrowded dwellings, poor nutrition, smoking, consumption of alcohol at hazardous levels, the use of illicit drugs and other harmful substances, and exposure to violence (ABS and AIHW 1999). These conditions can all contribute to high rates of disease and injury.
- Australia has the highest incidence of melanoma and other skin cancers in the world, and has experienced a number of outbreaks of vector-borne diseases such as Ross River virus and dengue fever in the last few years.
- Over the past two decades, more than 30 emerging diseases that afflict humans have been identified. Also, some of the diseases once thought to be under control have re-emerged as significant problems. Several different factors contribute to the emergence or re-emergence of diseases, including social, economic, political and ecological factors, and the interactions of organisms, hosts and the environment. The changing distribution of populations, the increase in international travel, the development of resistance to antimicrobials, changes in human behaviour and changes in the environment have all contributed to disease emergence.
Although environmental hazards are increasingly seen as important factors influencing health, there is insufficient data at present to systematically monitor environmental health at the national level.