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Mortality

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Mortality

Major impediments to producing a complete picture of Indigenous mortality in Australia are the incomplete identification of Indigenous status in death records and the experimental nature of the recently adopted population estimates [1]. As a result of the incomplete identification of Indigenous status in death records, the 2,620 deaths registered in 2012 where the deceased person was identified as Indigenous is certainly an underestimate of the actual number of Indigenous deaths.

Based on a linkage study of Indigenous identification in deaths registration and the 2011 Census undertaken by the ABS in revising its estimates of the expectation of life of Indigenous people (see ‘Life expectancy’), it is likely that the overall identification of Indigenous people in death registrations was around 87% [2].

The levels of under-identification, which differed by age-group, jurisdiction and remoteness of residence, were taken account of in the new estimates of Indigenous life expectancy. The ABS noted that correction of the under-estimates of death numbers and rates would need similar adjustments. These findings confirm the caution that the ABS notes should be exercised in the interpretation of the estimates of Indigenous mortality, particularly estimates of trends over time [1]. This caution is reflected in recent ABS publications that do not include detailed tables of Indigenous deaths, nor information about overall death rates. As a result, there is no consistency about the extent of information available for recent years. Reflecting this, readers should be aware that the following sections vary in terms of the years to which they relate.

Box 2: Adjusting for age-structures of populations

Comparison of Indigenous and non-Indigenous mortality needs to take account of differences in the age structures of the Indigenous and non-Indigenous populations using a process known as standardisation. (The process is also referred to as age-adjustment.)

Direct standardisation, the preferred method, applies detailed information about Indigenous deaths, including sex and age, to a ‘standard’ population [3]. (In Australia, the 2001 Australian estimated resident population (ERP) is generally used as the standard population.) Direct standardisation enables accurate comparisons of Indigenous and non-Indigenous rates, and time-series analyses.

If detailed information is not available, it is still possible to use indirect standardisation to estimate standardised mortality ratios (SMRs). SMRs allow for the comparison of numbers of registered Indigenous deaths with the numbers expected from the corresponding age-sex-specific death rates for the total population or, preferably, the non-Indigenous population. The SMR is the ratio of the numbers of deaths (or of other health measures) registered/observed to the number expected.

Age-standardised death rates

There were 2,620 deaths in Australia in 2012 where the deceased person was identified as Indigenous [4]. For NSW, Qld, WA, SA and the NT, the only jurisdictions with adequate identification of Indigenous status, the age-standardised death rate of 1,128 per 100,000 population for Indigenous people was 2.0 times the rate for their non-Indigenous counterparts.

More detailed information about death rates is available for the five-year period 2006-2010 for people living in NSW, Vic, Qld, WA, SA and the NT [5]. After age-adjustment, the death rate for Indigenous people living in those jurisdictions was 1.9 times the rate for non-Indigenous people (Table 5) [5]. The rates for Indigenous people were highest in the NT (1,541 per 100,000) and WA (1,431 per 100,000).

Table 5: Age-standardised death rates, by Indigenous status, and Indigenous:non-Indigenous rate ratios, NSW, Qld, WA, SA and the NT, 2006-2010
JurisdictionIndigenous rateNon-Indigenous rateRate ratio
Source: AIHW, 2013 [5]
Notes:
  1. Rates per 100,000 are directly age-standardised using the 2001 Australia estimated resident population
  2. Rate ratio is the Indigenous rate divided by the non-Indigenous rate
  3. Due to the incomplete identification of Indigenous status, these figures probably under-estimate the true difference between Indigenous and non-Indigenous rates
  4. Caution should be exercised in the interpretation of Qld rates because of recent changes to birth and death registrations
NSW 962 598 1.6
Qld 1,089 597 1.8
WA 1,431 574 2.5
SA 1,060 615 1.7
NT 1,541 645 2.4
NSW, Qld, WA, SA and the NT 1,151 597 1.9

Between 1991 and 2010, there was a 33% reduction in the death rates for Indigenous people in WA, SA and the NT; there was also a significant closing of the gap in death rates between Indigenous and non-Indigenous people during this time period [6].

Expectation of life

In 2013, the ABS published revised estimates for expectation of life at birth for Indigenous people [2]. After adjustment for the underestimate of the number of deaths identified as Indigenous, the ABS estimated that Indigenous males born in Australia in 2010-2012 could expect to live to 69.1 years, 10.6 years less than the 79.7 years expected for non-Indigenous males. The expectation of life at birth of 73.7 years for Indigenous females born in Australia in 2010-2012 was 9.5 years less than the expectation of 83.1 years for non-Indigenous females.

Revised estimates were also published for Indigenous people living in NSW, Qld, WA and the NT (Table 6) [2]. (It should be noted that the table includes two estimates for Australia. The ‘headline’ estimate includes adjustments based on Australia-wide census-related information. The headline estimates should be used in all situations except those requiring comparisons with the estimates for the states and territories, for which Australia-wide census-related information could not be applied. The unadjusted Australian estimate should be used in situations requiring such a comparison.)

Table 6: Expectation of life at birth in years, by Indigenous status and sex, selected jurisdictions, Australia, 2010-2012
JurisdictionIndigenous status/sex
IndigenousNon-IndigenousDifference
Source: ABS, 2013 [2]
Notes:
  1. This table includes two estimates for Australia. The ‘headline’ estimate includes adjustments based on Australia-wide census-related information. The headline estimates should be used in all situations except those requiring comparisons with the estimates for the states and territories, for which Australia-wide census-related information could not be applied. The unadjusted Australian estimate should be used in situations requiring such a comparison.
  2. Australian estimates are based on deaths in all states and territories
  3. Differences are based on unrounded estimates
Males
NSW 70.5 79.8 9.3
Qld 68.7 79.4 10.8
WA 65.0 80.1 15.1
NT 63.4 77.8 14.4
Australia (unadjusted) 67.4 79.8 12.4
Australia (headline) 69.1 79.7 10.6
Females
NSW 74.6 83.1 8.5
Qld 74.4 83.0 8.6
WA 70.2 83.7 13.5
NT 68.7 83.1 14.4
Australia (unadjusted) 72.3 83.2 10.9
Australia (headline) 73.7 83.1 9.5

Age at death

The median age at death6 in 2012 for Indigenous males ranged from 49.9 years for those living in the NT to 60.6 years for those living in NSW (Table 7) [1]. These levels were around 20 years less than those for non-Indigenous males, which ranged from 67.1 years (NT) to 80.2 years (SA).

The median age at death for Indigenous females in 2012 ranged from 52.8 years for those living in the NT to 63.9 years for those living in NSW and Qld (Table 7) [1]. These levels were also around 20 years less than those for non-Indigenous females, which ranged between 74.0 years (NT) and 85.6 years (SA).

Table 7: Median age at death, by Indigenous status and sex, NSW, Qld, WA, SA and the NT, 2012
JurisdictionIndigenousNon-Indigenous
MaleFemaleMaleFemale
Source: ABS, 2013 [1]
Notes:
  1. Information is not available for the other jurisdictions because of the relatively small numbers of deaths
  2. Median age of death is the age below which 50% of deaths occur
NSW 60.6 63.9 79.3 84.9
Qld 56.1 63.9 77.6 84.2
WA 54.8 61.1 77.9 84.4
SA 53.0 61.3 80.2 85.6
NT 49.9 52.8 67.1 74.0
All jurisdictions 55.0 61.3 78.7 84.7

In 2008-2012, age-specific death rates were higher for Indigenous people than for non-Indigenous people across all age-groups, but the rate ratios were highest in the young and middle adult years (Table 8) [1]. (The rate ratios, based on the numbers of deaths registered, vary according to the levels of Indigenous identification (see above).)

Table 8: Age-specific death rates, by Indigenous status and sex, and Indigenous:non-Indigenous rate ratios, NSW, Qld, WA, SA and the NT, 2008-2012
Age-group (years)IndigenousNon-IndigenousRate ratio
MaleFemaleMaleFemaleMaleFemale
Source: ABS, 2013 [1]
Notes:
  1. Rates are per 1,000
  2. Rate ratio is the Indigenous rate divided by the non-Indigenous rate
  3. Information is not available for Vic, Tas and the ACT because of the small number of deaths registered in those jurisdictions
NSW
0 4 4 4 3 0.9 1.1
1–4 35 30 16 16 2.2 1.9
5–14 12 11 16 7 1.2 1.5
15–24 83 39 47 20 1.8 2.0
25–34 187 92 73 31 2.6 3.0
35–44 398 237 122 67 3.3 3.6
45–54 780 428 276 165 2.8 2.6
55–64 1,426 994 645 386 2.2 2.6
65+ 4,730 4,371 4,119 3,676 1.1 1.2
Qld
0 8 7 5 4 1.7 1.7
1–4 39 63 22 18 1.8 3.5
5–14 17 16 12 9 1.4 1.8
15–24 124 63 54 26 2.3 2.4
25–34 244 125 86 35 2.8 3.6
35–44 509 278 129 68 3.9 4.1
45–54 951 527 264 160 3.6 3.3
55–64 1,753 1,370 627 363 2.8 3.8
65+ 5,957 4,844 3,871 3,449 1.5 1.4
WA
0 9 5 3 3 3.1 1.7
1–4 90 53 19 15 4.7 3.6
5–14 36 36 9 10 4.3 3.7
15–24 238 125 59 26 4.0 4.8
25–34 377 201 93 35 4.1 5.7
35–44 771 499 124 66 6.2 7.6
45–54 1,329 980 254 153 5.2 6.4
55–64 2,314 1,606 575 334 4.0 4.8
65+ 6,257 5,295 3,698 3,351 1.7 1.6
SA
0 6 6 3 3 1.7 2.0
1–4 0 73 25 15 0.0 4.9
5–14 17 18 8 8 2.1 2.2
15–24 174 99 53 21 3.3 4.8
25–34 300 166 84 35 3.6 4.8
35–44 725 500 144 82 5.0 6.1
45–54 1,298 903 299 187 4.3 4.8
55–64 2,070 1,297 665 396 3.1 3.3
65+ 4,352 3,927 4,262 3,895 1.0 1.0
NT
0 14 11 4 4 3.5 3.0
1–4 82 79 35 9 2.4 8.6
5–14 39 52 23 9 1.7 6.0
15–24 311 114 101 34 3.1 3.4
25–34 454 216 93 28 4.9 7.7
35–44 902 647 134 46 6.7 13.9
45–54 1,612 1,253 333 144 4.8 8.7
55–64 2,997 1,933 735 308 4.1 6.3
65+ 6,844 5,235 3,221 2,431 2.1 2.2
All jurisdictions
0 7 6 4 3 1.8 1.7
1–4 48 53 19 16 2.5 3.3
5–14 21 22 10 8 2.1 2.7
15–24 155 73 52 23 3.0 3.2
25–34 284 144 81 33 3.5 4.4
35–44 588 367 127 68 4.6 5.4
45–54 1,063 683 272 164 3.9 4.2
55–64 1,893 1,346 633 373 3.0 3.6
65+ 5,530 4,738 4,007 3,597 1.4 1.3

Infant mortality

The infant mortality rate (IMR) is the number of deaths of children aged less than one year in a calendar year per 1,000 live births in the same calendar year. In NSW, Qld, WA, SA and the NT in 2010-2012, the Indigenous IMR (6.4 per 1,000) was around twice as high as the non-Indigenous IMR [1]. The highest Indigenous IMRs occurred in the NT (15.6 for male infants and 11.7 for female infants); the lowest occurred in NSW (3.8 for both male and female infants) (Table 9).

Table 9: Infant mortality rates, by Indigenous status and sex, and Indigenous:non-Indigenous rate ratios, NSW, Qld, WA, SA and the NT, 2010-2012
JurisdictionIndigenousNon-IndigenousRate ratio
MalesFemalesMalesFemalesMalesFemales
Source: ABS, 2013 [1]
Notes:
  1. Infant mortality rate is the number of infant deaths per 1,000 live births
  2. Rate ratio is the Indigenous rate divided by the non-Indigenous rate
  3. The Indigenous rates are likely to be under-estimated, due to the incomplete identification of Indigenous status on births and deaths records
  4. Due to the small number of deaths registered in Vic, Tas and the ACT, these jurisdictions have been excluded
NSW 3.8 3.8 4.0 3.0 1.0 1.3
Qld 7.5 6.2 4.8 4.1 1.6 1.5
WA 8.5 4.4 2.8 2.5 3.0 1.8
SA 7.1 5.9 3.2 2.8 2.2 2.1
NT 15.6 11.7 3.5 4.0 4.5 2.9

In the five-year period 2006-2010, Indigenous infants most commonly died from the International Classification of Diseases (ICD): ‘Certain conditions originating in the perinatal period’, including birth trauma, disorders relating to foetal growth, and complications from pregnancy, labour and delivery [5]. Indigenous infants died from ‘Certain conditions originating in the perinatal period’ at twice the rate of non-Indigenous infants. The second most common cause of infant death was ICD ‘Congenital malformations’, for which Indigenous and non-Indigenous infants had similar rates (rate ratio of 1.2). The third most common cause of infant death was for ICD ‘Signs, symptoms and ill-defined conditions’, which includes sudden infant death syndrome (SIDS); Indigenous infants died at three times the rate of non-Indigenous infants (and, for SIDS alone, twice the rate).

From 1991 to 2010, there have been significant declines in IMRs for Indigenous and non-Indigenous infants in WA, SA and the NT: the rate has declined by 62% for Indigenous infants and by 43% for non-Indigenous infants [5]. The gap between Indigenous and non-Indigenous infants has closed substantially.

Causes of death

Cardiovascular disease was the leading cause of death of Indigenous people in 2012, being responsible for 25% of the deaths of Indigenous people living in NSW, Qld, WA, SA and the NT [4]. The next most common causes of death were neoplasms (mainly cancers) being responsible for 21% of deaths, followed by ICD ‘External causes’ (injury) (15%), ICD ‘Endocrine, nutritional and metabolic diseases’ (including diabetes) (9%) and ICD ‘Diseases of the respiratory system’ (8%). The information needed to make a valid comparison of the relative impacts of these causes among Indigenous and non-Indigenous people in 2012 is not available, so the following comparisons are restricted to some specific causes within each group.7

In terms of specific conditions, coronary heart disease was the leading cause of death of Indigenous people living in NSW, Qld, WA, SA and the NT in 2012 at a rate 2.1 times that of their non-Indigenous counterparts (Table 10) [4]. The other leading specific causes of death of Indigenous people were diabetes (rate ratio: 7.0), lung cancer (2.3) and chronic lower respiratory disease (2.9).

Table 10: Numbers and rates of the leading causes of Indigenous deaths and Indigenous:non-Indigenous rate ratios, NSW, Qld, WA, SA and the NT, 2012
Cause of deathNumberRateRate ratio
Source: ABS, 2014 [4]
Notes:
  1. See source for the ICD codes for the causes of death
  2. Rates are deaths per 100,000, standardised to the Australian 2001 Estimated Resident Population
  3. Rate ratio is the Indigenous rate divided by the non-Indigenous rate (not shown)
Coronary heart disease 338 165 2.1
Diabetes mellitus 201 106 7.0
Lung cancer 138 73 2.3
Chronic lower respiratory disease 123 74 2.9
Suicide 117 22 2.0
Cerebrovascular disease 108 67 1.5
Land transport accidents 88 20 3.4
Symptoms signs and ill-defined conditions 79 22 3.4
Cirrhosis and other liver diseases 72 23 4.1
Diseases of the urinary system 63 34 2.5

More detailed information about Indigenous mortality is available for the five-year period 2006-2010 for people living in NSW, Vic, Qld, WA, SA and the NT [5]. During that time period, cardiovascular disease was the most common cause of death for Indigenous people living in those jurisdictions, followed by ICD ‘Neoplasms’ (almost entirely cancer) (19% of Indigenous deaths) and ICD ‘External causes of death’ (injury) (15% of Indigenous deaths). For all major causes of death, Indigenous people died at higher rates than did non-Indigenous people (Table 11).

Table 11: Age-standardised death rates, by Indigenous status and cause, and Indigenous:non-Indigenous rate ratios, NSW, Qld, WA, SA and the NT, 2006-2010
Cause of deathRateRate ratio
IndigenousNon-Indigenous
Source: AIHW, 2013 [5]
Notes:
  1. Due to under-identification of Indigenous deaths, these rates are likely to under-estimate the true differences between the Indigenous and non-Indigenous populations
  2. Rates per 100,000 population have been standardised using the 2001 Australian estimated resident population
  3. Rate ratio is the Indigenous rate divided by the non-Indigenous rate
Circulatory diseases 351 201 1.7
Neoplasms 245 178 1.4
Endocrine, metabolic and nutritional disorders (including diabetes) 118 22 5.4
Respiratory diseases 112 49 2.3
External causes 84 37 2.3
Digestive diseases 58 20 2.8
Kidney diseases 40 11 3.5
Nervous system diseases 27 24 1.1
Infectious and parasitic diseases 25 8.7 2.9
Conditions originating in the perinatal period 6.0 2.8 2.2
Other causes 85 43 2.0
All causes 1,151 597 1.9

In 2011, the leading specific causes of death differed for Indigenous males and females living in NSW, Qld, WA, SA and the NT [7]. For Indigenous males and females, the two leading specific causes of death were coronary heart disease (also known as ischaemic heart disease) followed by diabetes; the third leading cause of death was suicide for Indigenous males and chronic lower respiratory diseases for Indigenous females. For non-Indigenous males, the leading causes of death were coronary heart disease, lung and related cancers, and cerebrovascular disease. For non-Indigenous females, the leading causes of death were coronary heart disease, cerebrovascular disease, and dementia (including Alzheimer’s disease).

Maternal mortality

In Australia in 2003-2005 (the most recent period for which detailed data are available), six (10%) of the 60 maternal deaths where Indigenous status was known were of Indigenous women (Indigenous status was not reported in 8% of the deaths) [8].

Reflecting the higher rate of confinements among Indigenous women, the maternal mortality ratio for Indigenous women in 2003-2005 was 21.5 deaths per 100,000 confinements, almost three times higher than the ratio of 7.9 per 100,000 for non-Indigenous women (Table 12) (Derived from [8]). For direct maternal deaths, the ratio of 7.2 per 100,000 for Indigenous women was twice the ratio of 3.6 per 100,000 for non-Indigenous women.

Table 12: Numbers of confinements and maternal deaths, and maternal mortality ratios, by Indigenous status, Australia, 2003-2005
Indigenous statusConfinementsMaternal deathsMaternal mortality ratio
Source: Derived from Sullivan, Hall, King, 2008 [8]
Notes:
  1. Maternal mortality ratio is the number of maternal deaths divided by the number of confinements (in 100,000s)
  2. Due to some uncertainty about the numbers of Indigenous deaths and confinements, some caution must be exercised in the interpretation of the ratios
  3. The non-Indigenous numbers and ratios include deaths for which Indigenous status was not known. This probably results in a slight, unknown over-estimate of non-Indigenous numbers and ratios, and a resultant under-estimate of the differences between Indigenous and non-Indigenous women
Indigenous 27,901    
Direct and indirect maternal deaths   6 21.5
Direct maternal deaths   2 7.2
Non-Indigenous 745,347    
Direct and indirect maternal deaths   59 7.9
Direct maternal deaths   27 3.6

Avoidable mortality

Avoidable mortality refers to deaths that could have been prevented with timely and effective health care, including early detection and effective treatment, as well as appropriate modifications of lifestyle behaviours (such as quitting smoking) [9].

In 2012, almost 1,500 of the deaths of Indigenous people living in NSW, Qld, WA, SA and the NT were avoidable [4]. After age-adjustment, the rate of avoidable deaths was 3.7 times higher for Indigenous people than for their non-Indigenous counterparts.

More details about avoidable deaths are not available for 2012, but there were 6,777 deaths from avoidable causes among Indigenous people living in NSW, Qld, WA, SA and the NT in the five-year period 2006-2010 [5]. Age-adjusted rates for avoidable deaths of Indigenous people were highest in the NT (787 per 100,000) and lowest in NSW (382 per 100,000). Indigenous people died from avoidable causes at 3.5 times the rate of non-Indigenous people living in NSW, Qld, WA, SA and the NT.

In 2006-2010, the most common conditions contributing to avoidable deaths among Indigenous people living in NSW, Qld, WA, SA and the NT were coronary heart disease (19%), cancer (17%), diabetes (10%), and suicide (8.5%) [5]. The death rates from avoidable causes were around two times higher for Indigenous people than for non-Indigenous people for cancer and suicide, four times higher for coronary heart disease, and 13.5 times higher for diabetes.

Between 1997 and 2010, there was a 24% decline in the death rate from avoidable causes for Indigenous people living in WA, SA and the NT [6]. The difference in rates between Indigenous and non-Indigenous people has decreased.

References

  1. Australian Bureau of Statistics (2013) Deaths, Australia, 2012. Canberra: Australian Bureau of Statistics
  2. Australian Bureau of Statistics (2013) Life tables for Aboriginal and Torres Strait Islander Australians, 2010-2012. Canberra: Australian Bureau of Statistics
  3. Australian Institute of Health and Welfare (2011) Principles on the use of direct age-standardisation in administrative data collections: for measuring the gap between Indigenous and non-Indigenous Australians. Canberra: Australian Institute of Health and Welfare
  4. Australian Bureau of Statistics (2014) Causes of death, Australia, 2012. Canberra: Australian Bureau of Statistics
  5. Australian Institute of Health and Welfare (2013) Aboriginal and Torres Strait Islander health performance framework 2012: detailed analyses. Canberra: Australian Institute of Health and Welfare
  6. Australian Health Ministers’ Advisory Council (2012) Aboriginal and Torres Strait Islander health performance framework: 2012 report. Canberra: Office for Aboriginal and Torres Strait Islander Health, Department of Health and Ageing
  7. Australian Bureau of Statistics (2013) Causes of Death, Australia, 2011. Canberra: Australian Bureau of Statistics
  8. Sullivan E, Hall B, King J (2008) Maternal deaths in Australia 2003-2005. Canberra: Australian Institute of Health and Welfare
  9. Page A, Tobias M, Glover J, Wright C, Hetzel D, Fisher E (2006) Australian and New Zealand atlas of avoidable mortality. Adelaide: Public Health Information Development Unit, University of Adelaide
  10. Becker R, Silvi J, Ma Fat D, L'Hours A, Laurenti R (2006) A method for deriving leading causes of death. Bulletin of the World Health Organization; 84(4): 297-304

Endnotes

  1. The median age at death is the age below which 50% of people die. Because the measure partly reflects the age structures of the respective populations, it is a less precise measure than age-specific death rates, which are summarised below.
  2. The list of specific causes, published in the Bulletin of the World Health Organization [10], was developed to enable comparisons between countries, but basic tabulation lists were acknowledged as better for monitoring disease over time.
 
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