Indigenous mortality: Placing Australian aboriginal mortality within a broader context

Sec. SC;. Med. Vol. 35, No. 3. pp. 335-346. 1992 Printed in Great Britain. All rights reserved

INDIGENOUS ABORIGINAL

Copyright

MORTALITY: PLACING MORTALITY WITHIN CONTEXT

0277.9536192 55.00 + 0.00 ‘C 1992 Pergamon Press Ltd

AUSTRALIAN A BROADER

ROBERT S. HOGG* Demography

Program,

Division of Demography and Sociology, Research School The Australian National University, Canberra, Australia

of Social Sciences,

Abstract-The purpose of this study was to evaluate whether contemporary Australian Aboriginal mortality patterns are different from those exhibited by Canadian Registered Indians, New Zealand Maoris, and American Indians and Alaskan natives. Data on Australian Aborigines were procured from published studies conducted in New South Wales, the Northern Territory, Queensland, and Western Australia; while data on Canadian Registered Indians, New Zealand Maoris, and American Indians and Alaskan natives were obtained respectively from unpublished tables produced by Health and Welfare Canada, the National Health Statistics Centre, and the Indian Health Service. Mortality patterns were compared by evaluating differences in life expectancy and in age- and cause-specific patterns of death. This analysis demonstrates that although Australian Aborigines, Canadian Registered Indians, New Zealand Maoris, and American Indians and Alaskan natives have similar patterns of high adult mortality, Australian Aborigines are generally characterized by lower life expectancies at birth and higher age- and cause-specific death rates. Overall, these findings suggest that the mortality patterns of Australian Aborigines are strikingly different from those exhibited by the other three indigenous populations and that existing information on risk, psychosocial, and genetic factors does not really explain why Australian Aborigines as compared to these other indigenous groups have such high rates of death and low life expectancy. Key words-indigenous Canadian Registered

mortality, Australian Aborigines, Indians, New Zealand Maoris

American

Indians

and

Alaskan

natives,

Gray [4] has briefly commented on similarities in Australian Aboriginal and Canadian Indian agespecific mortality levels. In this study I attempt to complement this existing body of research by comparing in greater detail the mortality patterns of Australian Aborigines, in various regions, with those exhibited by Canadian Registered Indians, New Zealand Maoris, and American Indians and Alaskan natives. The purpose here is to evaluate whether Australian Aboriginal mortality patterns are different from those exhibited by the other three indigenous populations.

INTRODUCTION

The numbers and health of indigenous people living in what is now Australia, Canada, New Zealand, and the United States rapidly deteriorated after AngloEuropean contact. Historically, initial depopulation and the high levels of mortality which persisted long after contact were mainly due to infectious diseases; presently, however, the varying high levels of mortality found in these populations are mainly due to degenerative diseases and accidental and violent events. Few comparative studies of contemporary indigenous mortality regimes have been conducted. Moodie’s [l] comparison of the mortality patterns of Northern Territory Australian Aborigines in 1964 and 1965 with those of New Zealand Maoris in 1964 and American Indians from 1961 to 1963 is one of the first more thorough investigations of this kind. More recently, Kenen [2] has compared contemporary Australian Aboriginal and American Indian mortality patterns; Kunitz [3] has remarked on the similarities and differences between the mortality experiences of Australian Aborigines, American and Canadian Indians, and New Zealand Maoris; and

METHODS

AND MATERIALS

Information on mortality and the population at risk for these four indigenous populations were obtained from a variety of published and unpublished sources. Data on Australian Aboriginal mortality were procured from regional studies conducted in the Northern Territory, 1979-1983 [5], the Queensland communities, 1984-1990 [6], Western Australia, 1983 [7], and western New South Wales, 1984-1987 [8]. In addition, country-wide estimates of Aboriginal mortality were taken from a study which combined 1985 mortality and population data for the Queensland communities, Western Australia, South Australia, and the Northern Territory [9]; and from another

*Address for correspondence: Canadian HIV Trials Network, 200-1033 Davie Street. Vancouver, British Columbia, Canada V6E lM7. 335

ROBERTS. How

336

Table I. Age and sex structure of the Australian Aboriginal.” Canadian Regtstered New Zealand Maoris.’ and American Indians and Alaskan nativesd populations bv sex Australian Aborigines (%)

Age group .Males 0 l-14 15-24 254 45-64 65-74 75 + Total’ Total population Ft?ndtV 0 l-14 15-24

25-44 45-64 65-74 7s + TotalC Total population

American Indians (Oh)

New Zealand Maoris (“~1

Canadian Indians (“/.)

Indlans,b m 1986,

2.8 24.5 37. I 24.2 8.9 1.7 0.7 lcQ.0 112.655

1.3 35.9 24. I 25.1 9.6 2.3 1.7 100.0 124,423

2.3 32.5 23.9 26.9 Il.9 1.7 0.6 100.0 148.360

2.5 30.9 22.9 26.4 12.7 3.1 1.6 100.0 73 I.332

2.1 23.0 36.2 25.5 9.8 1.9 0.5 100.0 114,990

1.3 33.9 23.7 27.0 9.9 2.3 I.9 100.0 126,974

2.2 31.2 23.5 28.2 12.1 2.1 0.8 100.0 147,460

2.3 29.3 22. I 27.0 13.5 3.7 2.1 100.0 751,319

‘Australian Bureau of Statistics 1986 census of population and housing. “Unpublished data from Health and Welfare Canada. ‘Unpublished data from National Health Statistics Centre. “Unpublished data from Indian Health Service. Totals may not add up because of rounding.

which produced national intercensal survival estimates of age-specific mortality and life expectancy at birth for the period 198 I-1986 (lo]. Data on Canadian Registered Indians [l I], and New Zealand Maoris, and American Indians and Alaskan natives [12] were obtained respectively from unpublished tables for the years 1981-1986 produced by Health and Welfare Canada, the National Health Statistics Centre, and the Indian Health Service [13]. Differences between Australian Aboriginal and Canadian Registered Indians, New Zealand Maoris, Table 2. Life expectancy

and American Indians and Alaskan natives mortality regimes were evaluated by examining patterns in life expectancy at birth and age 20 years and age- and cause-specific death rates. Life expectancies for these various populations were generated by constructing sex-specific life tables [14]; while age-specific mortality patterns were derived by computing age-specific death rates for each population by sex. Cause-specific death rates were calculated by indirectly standardizing [15], to the Australian age-structure in 1986 [16], indigenous age- and sex-specific death rates for the

at birth and age 20 years for various sex

indigenous

populations, Females

Males Age 0

Age 20

Age 0

Age 20

Ausrralia Australian Aborigines, 1981-1986’ Australian Aborigines, 198jb Northern Territory. 1979-1983c Queensland communities. 198&1990d Western Australia. 1983’ Western New South Wales, 198&1987’

55.7 52.8 51.6 54.8 55.7 53.5

n.a. 36.2 35.9 37.1 39. I 36.7

63.9 60.8 59.9 60.3 63.7 64.8

n.a. 44.1 43.3 42.9 46.0 46.7

Canada Registered

Population

64.4

48.9

73.6

56.8

New Zealand Maoris, 1981-1986h

65.6

47.5

70.9

52.9

Unired Sores American Indians and Alaskan natives, 1981-1986’

73. I

53.4

81.0

62.5

‘Ref. [IO]. bRef. (91. ‘Ref. [S]. ‘Ref. [6]. ‘Ref. 171. ‘Ref. ;Sj. *Unpublished %Jnpublished ‘Unpublished

Indians,

1981-1986s

data from Health and Welfare Canada. data from National Health Statistics Centre. data from Indian Health Service.

by

Australian

Aboriginal

mortality

337

Males

I1

0

I

5

10

I

I

15 20

I

I

I

II

11

’

25 30 35 40 45 50 55 60

11

1

65 70 75+

Age group

Females

.l’I 0

1 5

1 10

1 1 1 1 1 1 ’ 1 ’ ’ 15 20 25 30 35 40 45 50 55 60

’ ’ 1 65 70 75+

Age group Fig. 1. Age-specific death rates for Australian Aborigines from the Northern Territory (NT),” 1979-1983, Queensland communities (QLD),b 1984-1990, Western Australia (WA),c 1983, and western New South Wales (WNSW),d 1984-1987, by sex. “Ref. [5]; bRef. [a]; ‘Ref. [7]; dRef. [S]. major causes of death. Once rates were standardized, cause-specific standardized mortality ratios were constructed by comparing indigenous death rates (Australian Aboriginal, Canadian Registered Indians, New Zealand Maoris, or American Indians and Alaskan natives cause-specific rates) to those for the Australian population in 1986 [17]. Statistical significance was evaluated by determining whether the expected number of deaths exceeded the observed number at a 5% and 1% level of significance.

RESULTS

The population of Australian Aborigines is similar in size to that of Canadian Registered Indians (monitored by the Medical Service Branch) and New Zealand Maoris. The 1986 census estimates the total Australian Aboriginal population to be approx. 228,00&l 13,000 males and 115,000 females. This compares with Canadian Registered Indians and

New Zealand Maoris where the total populations in 1986 were estimated to be 251,000 and 296,000 respectively. However, these three indigenous populations are considerably smaller than population of American Indians and Alaskan natives living in reservation states in the same year (see Table 1). Although the sizes of these populations are somewhat different, their age structures are all relatively young. As shown in Table 1, approx 60% of the persons in these four populations are less than 25 years of age and under 5% are 65 years of age and over. There is also a marked imbalance in the sex structure-they all have a deficit of males. In all these population the ratios of males to females declines with age, but this sex imbalance is especially noticeable after the age of 45 years. As shown in Table 2, three distinct groups of male and female life expectancies are discernible: high life expectancies (American Indians and Alaskan natives); moderately high life expectancies (Canadian

ROBERTS. H~GG

338

Males

Australian Aborigines ((,,)1.*.*,(1*“1 Canadian Indians 11-1111.‘l’-‘l’l’

--.., .l

11 0 5

New Zealand Maoris American Indians

11 11 11 11 fi ’ 11 11 10 15 20 25 30 35 40 45 50 55 60 65 70 75+ Age group

1000 1

Females

al

Australian Aborigines “Y.““#Y,,.IUCanadian Indians 1lg.-ll-‘1*1’1’ .l

11 0 5

New Zealand Maoris American Indians

11 11 11 1 11 11 10 15 20 25 30 35 40 45 50 55 60

11 1 65 70 75+

Age group Fig.

2. Age-specific

mortality rates for Australian Aborigines,” Canadian Registered Indians,b New and American Indians and Alaskan natives’ from 1981-1986, by sex. “Ref. [IO]; bunpublished data from Health and Welfare Canada; ‘unpublished data from National Health Statistics Centre; “unpublished data from Indian Health Service. Zealand

Maoris,

Registered Indians and New Zealand Maoris); and low life expectancies (Australian Aborigines). In Australia, Aborigines from the Northern Territory have the lowest life expectancies, while Aborigines from Western Australia (males) and western New South Wales (females) have the highest. However, disparities in regional Australian Aboriginal life expectancy are relatively small compared to the differences between those of Australian Aborigines and the other indigenous populations. Although Australian Aborigines have much higher age-specific death rates than the other three indigenous groups, these differences are more discernible at younger and older ages than during early and middle adulthood. In Australia, age-specific death rates for Aborigines in the Northern Territory, Queensland, Western Australia, and western New South Wales are relatively similar with their characteristic pattern of high mortality in early and middle adulthood (see

Fig. 1). As shown in Fig. 2 a similar pattern of high adult mortality is observed in the age-specific rates for Canadian Registered Indians, New Zealand Maoris, and American Indians and Alaskan natives. However, this pattern of high adult mortality is not found in the general Australian population even when life expectancies were similar. Figure 3 shows that even when the 1921-1925 total Australian population (which had life expectancies at birth of 59 years for males and 63 years for females) is compared to the 1981-1986 Aboriginal population (with life expectancies of 56 years for males and 64 years for females), there are notable differences in age-specific death rates. In particular, Aborigines have much lower infant and higher adult age-specific death rates than did this general Australian population. Lastly, there are several notable variations in the patterns of cause-specific mortality. In Australia, although the underlying pattern of cause-specific

Australian Aboriginal mortality

339

Males

-

.l’I 0

I 5

1 I I I 1 1 1 11 10 15 20 25 30 35 40 45 50 Age group

Aborigines, 1981%

1 55

1 1 1 1 60 65 70 75+

Females

Australians, 1981-85 .l’I 0

1 1 I 1 1 I II 11 5 10 15 20 25 30 35 40 45 50 Age group

1 1 I 55 60 65

1 1 70 75+

Fig. 3. Age-specific death rates’ for total Australian population, 1921-1925” and 1981-1985b, and Australian Aborigines,’ 1981-1986, by sex. “Ref. [18]; bRef. [19] and ‘Ref. [lo]. mortality is relatively uniform, there are still prominent regional differences (see Tables 3 and 4). In particular, rates of infectious and parasitic and respiratory system diseases are highest among Aborigines in the Northern Territory; while rates of death from circulatory system diseases are highest among Aborigines in Western Australia and western New South Wales. When Australian Aboriginal rates are compared to those for indigenous groups in Canada, New Zealand, and the United States, rates of death from infectious and parasitic and circulatory and respiratory system diseases are higher among Australian Aborigines; while rates of death from injury, poisoning, and violence are higher among Australian Aborigines and Canadian Registered Indians (see Tables 5 and 6). On the whole, causespecific rates for Australian Aborigines tend to be the highest and those for New Zealand Maoris and American Indians and Alaskan natives the lowest.

DISCUSSION

The evidence presented here demonstrates that although Australian Aborigines, Canadian Registered Indians, New Zealand Maoris, and American Indians and Alaskan natives have similar patterns of high adult mortality, the relative importance of some more notable causes of death is strikingly different. Underlying disparities in cause-specific death rates most likely account for a large proportion of the differences in life expectancy between these indigenous groups. By virtually every health status measure presented here Australian Aborigines are much worse off than the other three indigenous groups. To begin, their life expectancy is much lower. National figures indicated that during the 1981-1986 period they had a life expectancy at birth of 56 years for men and 64 years for women [IO]. When regional disparities are compared, life expectancy at birth for either

340

ROBERT S. Hocc Table

3. Cause-specific

(NT).b

1979-1983. (WA):

Cause

death

the

rates’

for Austrahan

Queensland

1983. and

western

communities New

South

of death

Aborigines (QLD):

Wales

NT

from

the Northern

1984-1990.

(WNSW),’

1985-1987.

QLD

Territory

Western

Australia

by sex

WA

WNSW

Il.4

II.1

Males All

causes

Infectious

and

Malignant Circulatory

system

Respiratory

system

Digestive

All

10.8

0.7

0.3

0.2

09

I .o

I.2

1.3

3.4

3.6

4.7

4.5

*

and

2.5

1.3

0.6

0.5

0.2

0.9

0.9

ill-defined

08

I.4

1.0

1.0

and

2.3

2.2

1.7

1.6

2.2

0.8

I.2

I.1

poisoning

other

0.2

0.4

system

Symptoms Injury,

13.2 parasitic

neoplasms

violence

causes

Ft=‘em&S All

causes

Infectious

and

Malignant

parasitic

neoplasms

9.3

8.2

7.0

5.8

0.7

0.3

0.2

0.3

0.7

0.8

0.9

0.5

Circulatory

system

2.2

2.5

2.1

2.2

Respiratory

system

1.8

0.9

0.6

0.5

0.3

0.1

0.2

0.2

0.5

I.3

0.2

0.2

0.9 1.3

I.1

0.8

Digestive

system

Symptoms

and

ill-defined

Injury, poisoning All other causes ‘Rates

are

and

2.0

deaths

standardized

I .o

violence

per

1000

to the

population

1986 Australian

per

year.

1.7

Cause-specific

age structure.

Rates

I.?

rates

may

not

were

add

indirectly

up because

of

rounding “Ref.

[5].

‘Ref.

161.

‘Ref.

[7].

‘Ref.

IS].

Aboriginal men and women is lowest in the Northern Territory and highest in Western Australia (for males) and western New South Wales (for females). Gray [IO] indicates that Aboriginal mortality is higher in geographical areas of Australia which contain proportionately more remote communities, but the differences are actually quite small. Regional differences in life expectancies may also be due to the Table

4. Standardized

mortality

Territory

(NT).b

1979-1983.

Australia

(WA):

1983.

and

ratios’

the

differing reference periods. For example, Khalidi 1211 noted that in one region of the Northern Territory there was a marked increase in male and female life expectancy during the decade before the mid-1980s. Country-wide estimates of Aboriginal mortality demonstrate that diseases of the circulatory system were the leading cause of death for Aboriginal men and women in 1985. Death rates from these diseases,

for

Australian

Queensland

western

New

Aborigines

communities

South

Wales

from

(QLD).C

the

Northern

198&1990.

(WNSW):

Western

1984-1987.

by sex and

QLD

WA

WNSW

3.6.’

3.4.’

2.8.’

29.4*

13.2’

cause of death Cause

of death

NT

M&S All

causes

Infectious

and parasitic

8.6

3.6’; 10.3

Malignant

neoplasms

I .o

I.4

I.3

I.8

Circulatory

system

2.6”

3.3”

3.0.’

4.4’9

system

10.4**

6.3.’

I.9

2.8

3.5’

2.5

7.9’

10.0’

ill-defined

9.1**

16.7”

11.4’

and

4.1”

3.7”

2.9’

2.8.

4.8’

2.0’

2.4’

2.7’

Respiratory Digestive

system

Symptoms Injury, All

and

poisoning

other

violence

causes

11.0’

FtVUZkS All

causes

Infectious Malignant Respiratory Digestive

All ‘The

1.3

I.5

I .6

I.1

3.2”

2.3’

3.6’

system

15.8”

8.3.

5.3’

5.2’

4.6.

1.7

3.3

4.1

9.7’

25.4”

3.0

2.9

4.6”

4.2’

5.4.

3.8’

5.7..

4.0”

4.5’

and

ill-defined and violence

causes

ratio

of the number

Australian

male

difference

between

and

two

bRef.

151.

‘Ref.

[6].

‘Ref.

171.

‘Ref.

[8].

3.2.. 27.9

2.6’.

poisoning

other

16.8

24.2’

system system

Symptoms Injury,

52.0’

neoplasms

Circulatory

3.0”

3.9’.

4.2” and parasitic

asterisks

or

of deaths female

observed

death

rates

to the number applied.

the observed and expected represent

a significant

An

number

difference

of deaths asterisk

expected

represents

3.7* if 1986 total a significant

of deaths at a 0.05 probability at a 0.01

probability

level.

level;

Australian

Aboriginal

341

mortality

Table 5. Cause-specific death rates’ for Australian Aborigines, b 1985. Canadian Registered 1981-1986. New Zealand Maoris, ’ 1981-1986. and American Indians and Alaskan 1981-1986. by sex Cause of death

Australian Aborigines

Canadian Indians

New Zealand Maoris

Indians’, natives,c

American Indians

M&S

All causes Infectious and parasitic Malignant ncoplasms Circulatory system Respiratory system Digestive system Symptoms and ill-defined Injury, poisoning and violence All other causes

Il.7 0.6 I.0 3.3 I.6 0.4 0.4 2.2 2.2

8.3 0.1 0.7 2.0 0.6 0.4 0.3 3.4 0.8

6.3 0. I 1.4 2.2 0.6 0.2 0.2 0.9 0.7

6.3 0.0 0.6 I.8 0.4 0.5 0.2 I .9 0.8

FO?dt-J All causes Infectious and parasitic Malignant ncoplasms Circulatory system Respiratory system Digestive system Symptoms and ill-defined Injury, poisoning and violence All other causes

8.1 0.3 0.8 2.4 1.0 0.6 0.3 1.0 1.7

5.1 0.1 0.6 1.3 0.4 0.3 0.3 1.3 0.7

4.7 0.1 I.3 1.7 0.6 0.1 0.2 0.3 0.6

3.6 0.1 0.6 I.2 0.2 0.3 0.1 0.5 0.6

‘Rates are deaths per 1000 population per year. Cause-specific rates were indirectly standardized the 1986 Australian age structure. Rates may not add up because of rounding. bRcf. 19). ‘Unpublished data from Health and Welfare Canada. “Unpublished data from National Health Statistics Centre. ‘Ref. [20].

including ischaemic heart disease and other heart diseases, were more than twice those of the total Australian population in 1986 (91. Included in the category called injury, poisoning, and violence are deaths from motor vehicle accidents, suicide and self-inflicted injury, and homicide and injury purposefully inflicted by others; these were the second most frequent cause of death for males and the third most

to

frequent for females. Diseases of the respiratory system, including both acute and chronic conditions, constitute the third most frequent cause of death for Aboriginal males and the second for Aboriginal females. The pattern of Aboriginal mortality found in the states and territories is very similar to the 1985 country-wide pattern. For example, circulatory

Table 6. Standardized mortality ratios” for Australian Aborigines, b 1985. Canadian Registered Indians,’ 1981-1986, New Zealand Maoriqd 1981-1986, and American Indians and Alaskan natives,’ 1981-1986. by sex and cause of death Cause of death

Australian Aborigines

Canadian Indians

New Zealand Maoris

American Indians

ML&S All causes Infectious and parasitic Malignant neoplasms Circulatory system Respiratory system Digestive system Symptoms and ill-defined Injury, poisoning and violence All other causes

3.4” 25.9’ 1.4 2.7*’ 7.1.. 3.6. 4.5. 3.7” 4.9’.

1.9.. 5.0” 0.7” I .2* 2.0.’ 2.6’. 4.6** 5.6.’ 1.8’.

2.0” 4.5.. 2.0.8 2.1.’ 3.5.. I .6** 3.0** 1.5.’ 1.7..

1.3.’ 3.0.’ 0.6.. 0.9” 1.2” 3.0” 3.6** 3.0” 1.6..

Females All causes Infectious and parasitic Malignant neoplasms Circulatory system Respiratory system Digestive system Symptoms and ill-defined Injury, poisoning and violence All other causes

3.6” 25.1’ 1.4 2.8” 8.7** 8.4. 5.7. 4.4.’ 5.0**

I .9** 8.2’. 1.0 I .2’ 3.2’. 4.0” 5.4** 5.7’9 1.8..

2.4.. 6.0” 2.4” 2.5” 5.7** I.1 3.6’. I .4** 2.0’.

1.1’ 4.4’. 0.7.’ 0.7.’ 1.2** 2.7” 3.1.. 2.2”

1.5..

‘The ratio of the number of deaths observed to the number deaths expected if 1986 total Australian male or female death rate applied. An asterisk represents a significant difference between the observed and expected number of deaths at a 0.05 probability level; and two asterisks represent a significant difference at a 0.01 probability level. bRef. 191. ‘Unpublished data from Health and Welfare Canada. ‘Unpublished data from National Health Statistics Ccntre

342

ROBEKT S. HOGG

system diseases are the primary cause of death among Aborigines living in New South Wales [S. 221, the Northern Territory [S, 211, Queensland [6,23]. and Western Australia [7,24]. Although degenerative diseases of the heart, such as ischaemic heart disease. hypertensive heart disease, and cerebrovascular disease, tend to predominate, the underlying importance of these diseases do vary from state to state. There are also some notable differences in inter-regional cardiovascular death rates. A comparison of the mortality rates of Aborigines living in several Queensland Aboriginal reserves between 1976 and 1980 and other Queenslanders in 1978 by Lincoln and other (231 showed that deaths from cardiovascular diseases were well over twice as frequent on Aboriginal reserves. Among Aborigines living on Bloomfield River, Cherbourg, Mornington Island, Palm Island, and Woorabinda reserves, the death rates from heart disease were three to four times higher than the comparable rates for Queenslanders. Reserves which had significantly higher rates of death were those which were close to an urban centre and which had historically been established as receivers of Aborigines forcibly removed from other places. These reserves also tended to have a majority of people of mixed racial descent living a less traditional lifestyle

PI. Injury, poisoning and violence and respiratory system diseases also are major causes of death among Aborigines living in these various geographic regions. Sex specific rates from injury, poisoning, and violence for these regional populations are about 3-5 times higher than rates experienced by the total Australian population in 1986. The majority of these deaths tend to disproportionately occur at younger ages and to be from motor vehicle accidents and acts of intentional and self-inflicted violence. Although respiratory system diseases are important causes of death among these regional Aboriginal populations, the rates for these diseases are notably higher in the Northern Territory than elsewhere. The primary causes of deaths from respiratory system diseases are chronic obstructive lung disease, pneumonia and asthma. Canadian Registered Indians causes of death show a slightly different pattern from those exhibited by Australian Aborigines. Most noticeably, life expectancy for Registered Indians is much higher than for Australian Aborigines-approx 8 years higher for men and 10 years for women. Although circulatory system diseases are the primary cause of death in both populations, death rates for Registered Indians from this cause are much lower than those for Australian Aborigines. Registered Indians also have much lower rates of cancer. However both groups have high rates of death from injury, poisoning and violence. Among male Registered Indians, one-sixth of these deaths were from intentional means-suicide or homicide [26]. The high rate of deaths from motor vehicle accidents has been attributed to alcohol abuse, poorly maintained roads and motor vehicles, and

unqualified drivers; while fires which lead to death have likewise been attributed to alcohol abuse, poorly maintained and cleaned stove pipes, unsafe fire-fighting practices, and children playing with matches [27-291. Significant mortality differentials also exist between Maoris and Australian Aborigines. Based on 1981-1986 mortality experiences, Maori males at birth could expect to live 64 years while females could expect to live 68 years-about 6 and 8 years more respectively than their Australian Aboriginal counterparts. Coronary heart disease is the single most important cause of death among Maoris. Of particular concern is the excessive number of deaths from coronary heart disease occurring in Maori women [30]. Cancer is also a leading cause of death. In contrast with other indigenous populations examined here. Maoris have very high sex-specific death rates from cancer. While cancers of the lung and breast are numerically the most important cancers in Maoris, in comparison with the non-Maori population there is a striking excess risk of death from cancers of the stomach and cervix [30]. Injury, poisoning, and violence are also important causes of death. Motor vehicle accidents are the leading cause of death for the Maori. Deaths from suicide, especially among young men, have increased in the past two decades. Between 1970-1974 and 1980-1984 suicide rates for Maori men aged I5 to 24 years more than doubled [30]. Smith and Pearce [3l] have noted several important determinants of the high death rates found among Maoris aged 15-64 years during the 19741978 period. Compared with non-Maori death rates, 20% of the Maori male excess risk of death is attributable to marked ethnic differences in socio-economic status. Of the remaining excess risk, approx 15% is related to cigarette smoking, 10% to alcohol consumption (excluding accidental causes of death), and 17% to accidents. When differences in age and social class are standardized, Maori men are five times more likely than non-Maoris to die from rheumatic fever, hypertensive heart disease, nephritis, diabetes, and some respiratory system disease conditions. Findings for Maori women are similar to those for men with the following exceptions: mortality from coronary heart and cerebrovascular diseases also contributed significantly to Maori excess risk, and differences attributable to socio-economic status could not be estimated from available data. The life expectancy of American Indian and Alaskan natives is significantly higher than that of any other indigenous population examined here. As the life span of American Indians and Alaskan natives approaches that of the general United States population, the disease pattern of the Indian Health Service population also more closely resembles that of other Americans. For example, age-specific rates of heart disease in the service area population tend to resemble those in the general population. For the

Australian

Aboriginal

1983-1985 period, diseases of the heart were the leading cause of death for American Indians and Alaskan natives (as well as for the general American population) followed for men by injury, poisoning. and violence for women by malignant neoplasms [32]. Mortality rates have declined for those Indians and natives living both on and off reservations. A recent study observed that between 1970 and I978 there was a substantial decrease in age-specific mortality, especially for the zero to four years age group. However, this downward trend was not uniform; it was not experienced by females aged 65 years and over and by males aged 5-14 years and 65 years and over living on reservations. Overall, the study found that the mortality rates of Reservation Indians were higher than those of non-Reservation Indians, even though both rates have declined [33]. The reasons for the existence of these relatively large differences in the pattern of death among Australian Aborigines and the other three indigenous populations remain unclear. For example, existing but rather incomplete information on risk factor prevalence levels does not really explain why Australian Aborigines as compared to other indigenous groups have such high rates of death from circulatory system diseases [3, 341. Coronary heart disease risk factor prevalence rates are generally quite similar for these four populations. However, existing information does suggest that certain risk factors, such as obesity, are more important than others, such as high serum cholesterol; and that other previously unrecognized risk factors, such as hyperinsulinaemia (a high insulin response), may be significant [34]. Mortality differentials in infectious and parasitic and respiratory diseases could in part be due to differences in environment conditions and in lifestyle factors such as housing conditions, nutrition, and smoking [35]. Finally, disparities in death rates from injury, poisoning, and violence may be related to differences in the patterns of socialization, social organization, and social control found between mobile and semisedentary (predominantly found in Australian and Canada) and sedentary indigenous peoples (solely found in New Zealand and the United States) [3]. Psychosocial factors, such as the coping behaviour of individuals, may also contribute to the substantial variation in mortality rates [36]. To a large extent, an individual’s ability to take responsibility for his or her own life is constrained by environmental and social-cultural conditions which lead the individual to think that there is little he or she can do that will affect or improve the social situation. In order to cope with these situational constraints, individuals can try to: alter their perception of the problem; control the stress to which the problem gives rise; and/or change the situation that has created the problem. The approach an individual takes very much depends on his or her situation and on the available social and economic resources-for example, in the case of Aborigines, whether they are employed, live in a

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particular part of town, have a secondary education, or live in a household that is not overcrowded. Health risk behaviour, putting oneself at risk of ill health, may constitute a way in which an individual can deal with conflicts that arise in everyday life that cannot be controlled and a means of regaining the physical and psychological ability to cope with his or her situation. On the other hand, positive health behaviour may be an outcome of an individual’s ability to take control and responsibility for his or her own health and situation. While there are undoubtedly many sources of stress among Australian Aborigines, Sibthorpe [37] has identified several types which may affect health and have been noticeable in both the past and the present. These include: dispossession and institutionalization; separation and loss; unemployment; alienation and inequity; and stigmatization and assimilation. Although Sibthorpe’s schema was devised with Australian Aborigines in mind, it is also possible that these factors may influence the health risk or positive health behaviour of individuals in the other three indigenous groups. Finally, these disparities in indigenous mortality regimes may be due to differences in the genetic predisposition. For example, Neel [38. 391 has suggested that the high prevalence of non-insulin dependent diabetes mellitus in some contemporary human populations is due to the imposition of an over-sufficient and steady food supply on a thrifty genotype which was initially designed to take advantage of the sporadic food supply characteristically available to subsistence hunters and gatherers. Weiss and colleagues [40] have used a similar argument to explain why North American Indians and Mexican Americans of mixed descent have a higher prevalence of obesity, type 2 diabetes, and gallbladder disorders. This constellation of diseases, designated as the New World Syndrome [40], is thought to have arisen in American Indians by positive natural selection or genetic drift somewhat before or early in the settlement of North America. The current high rates of these diseases are thought to be attributable to the exposure of the genotypes associated with this syndrome to contemporary environmental conditions, especially those associated with recent dietary change. These results may also be affected by a number of shortcomings inherent in this present study. Most importantly, vital event data may not accurately record the pattern of death among these four indigenous population, but instead reflect the idiosyncratic manner in which each country classifies indigenous deaths and the persons at risk of dying. In Australia, information on Aboriginal deaths has been available from official death registration systems only since 1980, when in New South Wales a question of Aboriginality was first included as a data item on official death notification forms [22]. During the mid-1980s after being urged by the Task Force on

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Aboriginal Health Statistics [41], most states and both territories have been moving towards identifying Aboriginal deaths in their official collections [42]. Although these systems are now in place throughout Australia, mortality studies conducted during the last 10 years, based wholly or partly on listings of deaths supplied by state or territory registrars, have often noted that a large number of Aboriginal deaths are not identified [22,43]. To compensate for this lack of identification, researchers have often relied on local registry office records and listings of Aboriginal deaths produced by other agencies, such as the Aboriginal Health Services. These mortality studies have also had difficulties estimating the population at risk of dying. While the Australian population census remains the only comprehensive source of data on the Aboriginal population, the census coverage of Aborigines is often not complete. The 1986 census counts implied a growth rate of 42% for the Aboriginal population since the count was taken in 1981. While both censuses are generally free of any major inconsistencies, this very large intercensal growth rate in the Aboriginal population is probably due to the increased propensity of people to record themselves and their households as being Aboriginal [44]. In Canada, the Medical Service Branch’s administrative and public health program statistics constitute the main source of the numerator and denominator data for the generation of crude and age-specific death rates. However, mortality statistics are generally only available for a select group of Canadian Aborigines-Registered Indians. Other groups, such as Metis and non-status Indians, are not recognizable in the statistics as distinct groups, The quality of the data also varies markedly from one region to another depending on the context in which the data are collected and reported (451. In terms of statistical reporting the regions may be broadly divided into two categories: regions which use the provincial or territorial health care services to collect data (Alberta, Saskatchewan, Manitoba, Yukon, Northwest Territories and previously, British Columbia); and regions which rely on Medical Service Branch personnel to collect data (Ontario, Quebec, and the Atlantic provinces). Provincial or territorial health care services gather data on the entire Registered Indian population while Medical Services Branch personnel collect data only on the Registered Indians they serve [46]. In New Zealand, the National Health Statistics Centre is the main source of Maori mortality data. However, the validity of these mortality statistics has in the past been questioned for two main reasons [47]. First, information on the population at risk of death and the number of deaths in a given year come from two different sources. For any given year, estimates of the population at risk are based on census counts, while estimates of the total number of deaths are based on information extracted from death regis-

tration forms. Second, the death registration data themselves may be unreliable, because of the process by which ethnicity is documented. The main problem is not that Maoris are being misclassified as other nationalities, but that ethnic information is not obtained for all deaths. Ethnic classification on death registration forms is based on the biological origin of the parents of the deceased as reported by a close relative. A deceased person classified as Maori if the average of the fractions of ‘Maori blood’ of his or her parents is greater than or equal to one-half. The degree of Maori blood of the deceased parents is recorded by the funeral director in the ‘ethnic origin’ section of the death certificate. Unless a funeral director suspects that the deceased was of Maori descent and is willing to pursue the question of ethnic origin with a close relative, the ethnicity section is left blank. All blank responses are coded as ‘other’non-Maori or non-Pacific Islander. In the United States, census counts of American Indians and Alaskan natives have been shown to suffer from problems of inconsistency. Passe1 and Berman [48] estimate that the 1980 census count of American Indians and Alaskan natives represents more than a 70% increase over the 1970 census count. Increases occurred in most states, but the amount varied considerably, especially in non-Reservation states. These differences are for the most part outside expected natural increases and sample variability, and suggest that like Australian Aborigines there is an increasing propensity for people in the United States to record themselves as being American Indian or Alaskan native. Although the overall effect of these peculiarities is impossible to measure, it is bound to play some role in distorting age- and cause-specific mortality patterns and the underlying similarities and differences in the mortality regimes of these indigenous populations. Thus, small and statistically insignificant differences in standardized rates must be viewed cautiously. In conclusion, although Australian Aborigines, Canadian Registered Indians, New Zealand Maoris. and American Indians and Alaskan natives have similar patterns of high adult mortality, the relative importance of some more notable causes of death is strikingly different. Underlying disparities in causespecific death rates, especially from infectious and parasitic and circulatory and respiratory system diseases and injury, poisoning, and violence, account for some of the differences in life expectancies between these indigenous groups. However, existing but rather incomplete information on risk, psychosocial, and genetic factors for these various diseases does not really explain why Australian Aborigines as compared to other indigenous groups have such high rates of death and low life expectancy. Ackno,cledgemenrs-This paper is based on research undertaken as a Ph.D. student at the Australian hTationa1

Australian Aboriginal mortality University. In particular, I would like to acknowledge the assistance given to me by Drs Alan Gray, Geoffery McNicoll, Lincoln Day and Robert Attenborough. I would also like to extend my gratitude to Health and Welfare Canada, the National Health Statistics Centre, and the Indian Health Service who so willing supplied me with unpublished mortality data for this comparison. I would also like to thank Aaron Handier for his comments on an earlier draft of this paper and Heather Hogg for editing this paper. REFERENCES

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