Health Status: Life expectancy trends
A girl born in 1993 has a one-in-four chance of reaching 90 years of age. For a boy the probability is one-in-ten.
Increasing life expectancy has been an important social change this century. In the period 1901-10 the average life expectancy of a new-born boy was 55 years and that of a new-born girl 59 years. By 1993, a new-born boy had a life expectancy of 75 years and a new-born girl 81 years; an increase of 20 years for boys and 22 years for girls.
The increase in life expectancy is mainly due to fewer deaths of young children, particularly in the first year of life (infant mortality). The high mortality rates among infants during the period 1901-10 (about 1 in 10 died in the first year of life) kept the average life expectancy at birth low. Children who survived these early years then had life expectancies nearer to those currently experienced. For example, the life expectancy of a 5 year old boy differed by 13 years between 1901-10 and 1993 compared to 20 years for a new-born boy.
The reduction in mortality in the early part of this century is attributed to improvements in social conditions, such as better water supplies, sewage systems, food quality, health education etc. The continuing reduction in mortality in the latter half of the century is attributed to improving social conditions and advances in medical technology such as mass immunisation and antibiotics1.
The past two decades in particular have seen further increases in life expectancy, both at birth and at older ages. These increases are due in part to lower infant mortality, fewer deaths among young adults from motor vehicle accidents and fewer deaths among older males from heart disease. The reduction in the number of deaths from heart disease is related to behavioural changes, such as dietary improvements, reduced smoking and increased fitness1.
The social effects of improved life expectancy at older ages include an increase in the aged population and the associated issues of income support for the aged and their need for health resources. However, the impact on the individual receives little attention. Laslett uses the term the Third Age to refer to the lengthy period of active life following retirement and points out that it is a distinct and significant phase in most people's lives. He considers it to be an era of personal fulfilment2. Mortality statistics cannot tell us if the years of extra life can, or will improve an individual's quality of life. A 1992 report recommended that the Commonwealth Government recognise that 'the changing demographic structure of the population requires reassessment of the value and importance, both socially and economically, of life outside traditional work'3.
 | Average years of life remaining at age | |||
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| Period/year | 0 | 5 | 45 | 75 |
| Men | | | | |
| 55.2 | 57.9 | 24.8 | 6.6 |
| 63.5 | 62.6 | 26.9 | 7.2 |
| 67.9 | 64.8 | 27.4 | 7.5 |
| 75.0 | 70.6 | 32.5 | 9.5 |
| Women | | | | |
| 58.8 | 60.8 | 27.6 | 7.6 |
| 67.1 | 65.6 | 29.7 | 8.2 |
| 74.2 | 70.8 | 32.4 | 9.2 |
| 80.9 | 76.4 | 37.4 | 12.0 |
Source: Australian Life Tables; Death Registrations
| Life expectancy Life expectancy is a measure of current mortality rather than a predictor of future lifespan since age-specific death rates can change over time. Life expectancy at birth is often wrongly interpreted to mean that most people die at that age. The average life expectancy gives no indication of the variation in life expectancies. Life expectancy is the average number of additional years a person of a given age and sex might expect to live if they experience the current age-specific death rates from that age onwards through the rest of their life. Life expectancy is calculated separately for each sex. This is done one year at a time by taking a hypothetical group of new-born babies and, using the current probability of dying at each year of age, calculating the expected number of survivors at each age. The expected number of survivors slowly diminishes until the whole group have 'died'. Life expectancy at an age is calculated by dividing the number of person-years lived beyond that age by the number of people alive at that age. Age-specific death rate is the number of deaths at a specified age in a year per 1,000 of the mid-year population of that age. Age-specific death rates are used to calculate the probability of dying at a particular age. |
Life expectancy at different ages
Although life expectancy at birth is commonly used, particularly as a measure of comparative health status, it is possible to calculate life expectancy at any age. No matter how old a person becomes, they always have some chance of living longer. For example, life expectancy at birth in 1993 was 81 years for girls and 75 years for boys. However, at age 80 years, female life expectancy was an additional 9 years and male life expectancy an additional 7 years. The difference between life expectancies for males and females reduces with age as their mortality rates converge.
Source: Death Registrations
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| International comparison | | | | |
| Australians have an average life expectancy that compares well with other developed nations. Among the selected countries with data for 1990-91, the life expectancy at birth of Australian males and females (74 and 80 years respectively) was exceeded by three countries. Japanese males and females had the highest life expectancies (76 years and 82 years respectively). | | |||
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| LIFE EXPECTANCY AT BIRTH FOR SELECTED COUNTRIES | | |||
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| | Year/period | Males | Females | |
| Country | | Years | Years | |
| | ||||
| Australia | 1991 | 74.4 | 80.3 | |
| Canada | 1985-87 | 73.0 | 79.8 | |
| China(a) | 1985-90 | 68.0 | 70.9 | |
| France | 1990 | 72.8 | 80.9 | |
| Hong Kong | 1990 | 74.6 | 80.3 | |
| Indonesia(a) | 1985-90 | 58.5 | 62.0 | |
| Italy | 1989 | 73.5 | 80.0 | |
| Japan | 1991 | 76.1 | 82.1 | |
| Korea (Republic of) | 1989 | 66.9 | 75.0 | |
| Malaysia(a) | 1985-90 | 67.5 | 71.6 | |
| New Zealand | 1989 | 72.4 | 78.3 | |
| PNG(a) | 1985-90 | 53.2 | 54.7 | |
| Singapore | 1991 | 73.5 | 78.0 | |
| Sweden | 1991 | 74.9 | 80.5 | |
| UK | 1988-90 | 72.7 | 78.3 | |
| USA | 1989 | 71.8 | 78.6 | |
| | ||||
| (a) Estimated by the Population Division of the UN. Source: United Nations Demographic Yearbook 1992 | | |||
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Life expectancy for men and women
In 1993 a new-born girl had a life expectancy 6 years greater than a new-born boy. This life expectancy advantage of females over males has varied over time. Throughout the early part of this century it was about 4 years. In the latter half the difference increased, peaking at 7 years in the early 1980s. Since then the difference has steadily declined.
The difference in life expectancy between males and females has been attributed to both biological and environmental factors. Females are estimated to have a genetic advantage of about two years of life over males4. The remaining differences are attributed to the different behavioural and lifestyle patterns of males and females which result in different mortality rates. For example, in 1981, the life expectancy difference between females and males at birth was 7 years. The major reasons for this difference were the different death rates for males and females from heart disease; bronchitis; emphysema; asthma; cancers of the lung, trachea and bronchus; and accidents, particularly motor vehicle accidents5. These causes of death are related to smoking (see Australian Social Trends 1994, Tobacco use), which is more prevalent among men, and the risk taking behaviour of men, particularly young men.
Since the early 1980s, the difference in life expectancy between males and females has decreased while average life expectancy for both men and women has continued to increase. This has been due to the faster decline of mortality rates among males than females.
Source: Death Registrations
Survival
In 1901-10 half of new-born boys could have been expected to reach 64 years of age and half of new-born girls could have been expected to reach 68 years of age. The equivalent figures in 1993 were 78 years for males and 84 years for females.
The high mortality at young ages in 1901-10 is vividly demonstrated by comparing the survival curves with those for 1993. In 1901-10, 25% of males would have died by the age of 42 years and 25% of females by the age of 45 years (if the age-specific death rates had remained constant). In 1993, mortality rates were much lower and, if they remained constant, 25% of males would die before the age of 69 years and 25% of females before the age of 76 years.
Comparison of survival ages for the longest living 25% of each group reveals a smaller difference between 1901-10 and 1993. During 1901-10, 25% of males would have still been alive after 75 years and 25% of females after 79 years. In 1993, the period will be 85 years for males and 90 years for females.
Source: Australian Life Tables; Death Registrations
| Survival curves Like life expectancies, survival curves are based on the probability of death at each age. However, rather than estimating the average length of life, they show the proportion of people expected to survive to a given age, assuming that the age-specific death rates of the period remain constant. |
Aboriginal and Torres Strait Islander life expectancy
There are data limitations in calculating life expectancy figures for indigenous people. The current ABS assessment is that registrations of deaths of indigenous people in SA, WA, NT and ACT are reliable enough to publish. To calculate age-specific death rates the total number of people of that age must also be accurately known. Census counts of indigenous people are acknowledged to be incomplete, though the quality of the count has constantly improved. Because of these difficulties the ABS has only recently published experimental estimates for indigenous people.
Independent researchers have used alternative methods to estimate life expectancies of indigenous people. Recent research used 1986 and 1991 census counts and death registrations to estimate the life expectancy at birth of indigenous males to be 57 years, and for indigenous females to be 64 years6. There were considerable variations in the estimates between different states and territories.
Endnotes
1 Jain, S.K. (1994) Trends in Mortality National Centre for Epidemiology and Population Health and ABS.
2 Laslett, P. (1989) A Fresh Map of Life: The Emergence of the Third Age Weidenfeld and Nicolson, London.
3 Report of the House of Representatives Standing Committee for Long Term Strategies (1992) Expectation of Life: Increasing the Options for the 21st Century AGPS.
4 Hugo, G. (1986) Australia's Changing Population Oxford University Press.
5 Pollard, J.H. (1986) Causes of Death in Australia 1971-81 Journal of the Australian Population Association Vol.3, No.1, 1986.
6 Gray, A. and Tesfaghiorghis, H. (1993) Aboriginal Population Prospects Journal of the Australian Population Association Vol.10, No.2, 1993.
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