Aboriginal and Torres Strait Islander Health Performance Framework - 2010

1.18 Median age at death

Page last updated: 26 May 2011

Why is it important?:

The median age at death represents the age at which exactly half the deaths registered (or occurring) in a given time period were deaths of people above that age and half were deaths below that age. Median age at death is a general measure of the health status of a population. It is affected by the same factors determining life expectancy and general mortality rates. These include socioeconomic status (such as employment, income, education and economic wellbeing), lifestyle factors (such as tobacco use, excessive alcohol consumption, poor nutrition, lack of exercise), environmental factors (such as overcrowding in housing, lack of clean drinking water and adequate sanitation), genetic factors, the quality of the health system and the ability of people to access it.

A possible advantage of the median age measure is that it may be less impacted by under-identification of Indigenous people in mortality statistics if the people identified in deaths data have similar age characteristics to those that are not. For other measures, such as death rates, under-identification makes it difficult to calculate accurate population rates. Therefore median age at death has been suggested as an additional measure to complement mortality rates and life expectancy measures. However, there are several significant limitations of median age at death (Coory & Baade 2003). Median age at death is affected by the age structure of the population. In a population with a high fertility rate and a large propor­tion of younger people, a higher proportion of deaths will occur at a young age than in a population with low fertility and a small proportion of young people. Comparisons of Indigenous and non-Indigenous median age at death are severely impacted by the very different age distributions of these two populations.

Median age at death does not necessarily change significantly as mortality levels change. For example, modeling has shown that for Indigenous Australians, a two-year increase in the median age at death over five years would require a 30% decrease in the mortality rates, but the same increase in the median age at death for non-Indigenous Australians would mean only a 15% decrease in mortality (Coory & Baade 2003).

Findings:

Reliable deaths data for Aboriginal and Torres Strait Islander peoples are only available for New South Wales, Queensland, Western Australia, South Australia and the Northern Territory. During the period 2004–08 the median age at death for these jurisdictions combined was 52 years for Indigenous males and 77 years for non-Indigenous males—a gap of 25 years. The median age at death was 59 years for Indigenous females and 83 years for non-Indigenous females—a gap of 24 years. As noted above, these measures are significantly impacted by the differences in age structure of the Aboriginal and Torres Strait Islander population and the non-Indigenous population.

Median age at death varies between jurisdictions. In 2004–08 the median age at death for Indigenous males was 46 years in the Northern Territory, 48 years in South Australia, 51 years in Western Australia, 53 years in Queensland and 57 years in New South Wales. For Indigenous females the median age at death was 54 years in the Northern Territory, 55 years in South Australia, 60 years in Western Australia, 59 years in Queensland and 63 years in New South Wales. The age profile for the Indigenous population varies by jurisdiction with the Northern Territory having a younger age profile than New South Wales.

For the three jurisdictions with adequate quality data for long-term trends (WA, SA and the NT), between 1991 and 2008 median age at death for males has fluctuated year-to-year, with an overall significant increase of 3.2% over the 17 year period. Median age at death for females has also fluctuated year to year, with an overall significant decline of 1.4% over the period. This decrease is difficult to interpret due to changes in the population structure over this period. The median age at death statistics contrast with the estimates for all-cause mortality—which are adjusted for age structure and show that for the same jurisdictions, mortality rates decreased for males by 23% and decreased for females by 27% (see measure 1.22).

The first quartile of age at death is the age below which 25% of deaths occur. Trends in the first quartile of age at death are an indication of change in the deaths of young people, children and young adults. The first quartile of age at death increased between 1991 and 2008 for Aboriginal and Torres Strait Islander peoples in the three jurisdictions combined. The increase was significant for Aboriginal and Torres Strait Islander females but not for males. The third quartile of age at death is the age below which 75% of deaths occur. For the three jurisdictions combined, this remained fairly stable for males and increased slightly (but significantly) for females over this time period.

Implications:

Median age at death increased non-signficantly for Indigenous males between 1991 and 2008 and decreased non-significantly for Indigenous females. A decline in median age at death suggests that a higher proportion of deaths are occurring at a younger age. This could be due to a range of possible changes. However, the increase in the first quartile of age at death for Aboriginal and Torres Strait Islander women suggests that there was a relative reduction in the propor­tion of deaths occurring in girls and young women. Over the same time period, the overall death rate for the same three jurisdictions decreased (see measure 1.22). This suggests that the decrease in the median age at death for Indigenous women was most likely because of a greater relative decrease in deaths for the young age groups.

Figure 50 – Median age at death, by Indigenous status and sex, WA, SA and NT, 1991–2008


Figure 50 – Median age at death, by Indigenous status and sex, WA, SA and NT, 1991–2008
Source: AIHW and ABS analysis of National Mortality Database
Text description of figure 50 (TXT 1KB)

Table 27 – Median age at death, by Indigenous status and sex, NSW, Qld, WA, SA and NT, 2004–2008

Indigenous
Non-Indigenous
Male
Female
Male
Female
NSW 57 63 77 83
Qld 53 59 76 83
WA 51 60 76 83
SA 48 55 78 84
NT 46 54 64 71
Total of 5 jurisdictions 52 59 77 83
Source: AIHW and ABS analysis of National Mortality Database

Figure 51 – First quartile, median and third quartile of age at death, Indigenous males, WA, SA and NT, 1991–2008


Figure 51 – First quartile, median and third quartile of age at death, Indigenous males, WA, SA and NT, 1991–2008
Source: AIHW and ABS analysis of National Mortality Database
Text description of figure 51 (TXT 1KB)

Figure 52 – First quartile, median and third quartile of age at death, Indigenous females, WA, SA and NT, 1991–2008


Figure 52 – First quartile, median and third quartile of age at death, Indigenous females, WA, SA and NT, 1991–2008
Source: AIHW and ABS analysis of National Mortality Database
Text description of figure 52 (TXT 1KB)

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