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Health Status: Life expectancy trends LIFE EXPECTANCY AT SELECTED AGES
LIFE EXPECTANCY AT SELECTED AGES Source: Australian Life Tables; Death Registrations
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. LIFE EXPECTANCY BY AGE, 1993 Source: Death Registrations
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. DIFFERENCE BETWEEN FEMALE AND MALE LIFE EXPECTANCY AT BIRTH 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. PROPORTION OF PEOPLE SURVIVING TO A GIVEN AGE (SURVIVAL CURVES) Source: Australian Life Tables; Death Registrations
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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