Introduction

Cardiovascular disease (CVD) is a major health problem in the Australian Indigenous population. The leading cardiovascular conditions contributing to increased mortality are coronary heart disease, stroke and hypertensive disease. Rheumatic heart disease, although not a common contributor to mortality from CVD in the non-Indigenous population, is evident in the Indigenous population, primarily because of increased prevalence of rheumatic fever, especially in children.

The prevalence of cardiovascular conditions among Indigenous Australians is attributed to a range of risk factors. Reducing the risk factors that predispose the Indigenous population to CVD is expected to reduce the prevalence and mortality from all CVDs. In order to accomplish this, attention must be placed on primary and secondary prevention, as well as rehabilitation of patients who have experienced a cardiovascular episode.

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Prevalence of risk factors in the Indigenous population

The major CVD risk factors for the Indigenous population are the same as those for the total population, but the prevalence of these risk factors is often much higher among Indigenous people. As is true for many health issues, the high prevalence of risk factors found among the Indigenous population reflects the broader social and economic disadvantages faced by Indigenous Australians: 'people in lower socioeconomic groups are more likely to die from cardiovascular disease compared with people in higher socioeconomic groups' [1]. The risk factors summarised briefly in this section are smoking, physical inactivity and psychological and sociological aspects. These risk factors contribute significantly to the development of cardiovascular conditions in the Australian Indigenous population. Smoking heightens the risk of CVD by affecting the functioning of the arteries; physical inactivity contributes to increased weight gain; and psychological and sociological risk factors stem from social inequalities and influence the prevalence of other CVD risk factors.

According to the 2001 NHS, the age-standardised prevalence for ‘circulatory problems/diseases’ was 19% among Indigenous respondents, and 17% among non-Indigenous respondents [29]. Indigenous people living in remote areas were more likely to report having ‘circulatory problems’ than those living in non-remote areas (24% compared with 18%). Of Indigenous people aged 35-44 years, 16% reported a cardiovascular condition, the proportion increasing to 31% for those aged 45 to 54 years, and to 47% for those aged 55 years or over [30]. The most commonly reported circulatory system disorder in Indigenous people over 25 years of age was hypertension. The prevalence of hypertension increases with age – among Indigenous people prevalence increased from the age of 35 years, with onset approximately 10 years younger than for non-Indigenous people.

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Smoking

The 2001 National Health Survey (NHS) found that 51% of Indigenous people aged 18 years or older were current smokers, compared with 24% of non-Indigenous people [2]. For each population, all except 2% of current smokers reported smoking daily. Similar proportions of Indigenous males and females reported smoking and, importantly, the proportions were high across all age groups (Table 1). Overall, the proportion of Indigenous people living in remote areas who reported smoking (56%) was slightly higher than the proportion for those living in non-remote areas (49%). The levels documented in the 2001 NHS are similar to those reported from the earlier surveys [3,4].

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Physical inactivity

There are virtually no detailed data on the levels of physical activity among Indigenous people, but the 2001 NHS reported that 43% of Indigenous people aged 18 years or older living in non-remote areas were sedentary, compared with 30% of non-Indigenous people [2]. But, if this measure of physical activity is combined with the next category, 'low exercise level' (Indigenous people: 30%; non-Indigenous people: 39%), the differences between Indigenous and non-Indigenous people are significantly reduced. Anecdotal evidence suggests the differences are greater than these statistics indicate, but there are no hard data with which to establish the true position.

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Psychological and sociological factors

The risk factors outlined above are important predictors of cardiovascular disease, but recent research has shown that these factors explain just a quarter to a third of prevalence rates. Increasingly research, has focused on the role of psychosocial factors in the development of coronary heart disease. This research has identified social exclusion as one of ten psychological and sociologically based causal factors for ill-health, including cardiovascular disease [5].

Social isolation, depression and lack of social support have now been acknowledged as independent factors associated with the cause and prognosis of coronary heart disease (CHD), and that the risk contributed by these factors is 'of similar order' to the 'conventional' risk factors (smoking, dyslipidaemia and hypertension) [6]. Indigenous people have been identified as an at-risk population whose social disadvantage is strongly associated with both psychosocial and conventional risk factors. The acknowledgment of the equal importance of these psychosocial factors (social isolation, depression and lack of social support) and the conventional risk factors has clear implications for the assessment and management of Indigenous people with CHD, and for public health policy and research [6].

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General mortality and morbidity

Mortality

CVD was the leading cause of death for Indigenous people living in Western Australia, South Australia, and the Northern Territory combined for the period 1997-1999, being responsible for 30% of all deaths identified as Indigenous [7].

The more detailed breakdown of deaths from CVD, for 1996-2000, reveals that the number of Indigenous deaths from CVD was more than three times the number expected from rates for the non-Indigenous population (see Table 1). The leading specific cause of death for both Indigenous males and females for this period was coronary (ischaemic heart disease), for which cause there were around three times more deaths than expected. For cerebrovascular disease (stroke), the SMR was 3.3 for males and 2.4 for females. Rheumatic heart disease was responsible for relatively few deaths, but the SMR was 27.0 for males and 23.3 for females.

Table 1: Numbers of Indigenous deaths from cardiovascular disease and standardised mortality ratios (SMRs), by sex, WA, SA and the NT, 1996-2000

Category of cardiovascular disease
Indigenous males
Indigenous females
Number
SMR
Number
SMR
All cardiovascular disease
712
3.4 (3.2-3.7)
527
3.1 (2.9-3.40
Coronary heart disease
411
3.2 (2.9-3.5)
241
2.9 (2.6-3.3)
Stroke
123
3.3 (2.7-3.9)
112
2.4 (1.9-2.8)
Heart Failure
30
4.3 (2.9-6.1)
29
3.3 (2.2-4.7)
Rheumatic heart disease
27
27.0 (17.8-39.3)
42
23.3 (16.8-31.6)
Other cardiovascular disease
117
3.3 (2.7-4.0)
100
3.4 (2.8-4.2)

Source: Derived from data provided by the AIHW National Cardiovascular Disease Database and ABS low series population projections
Notes:
1 Standardised mortality ratio (SMR) is the ratio of the actual number of deaths identified as Indigenous and the number expected from the age-specific rates of the same-sex non-Indigenous population
2 The numbers and SMRs in this table have not been adjusted for the likely under-identification of Indigenous people in deaths registrations. Based on the estimated completeness of identification for WA, SA and the NT, the numbers and SMRs shown here could be up to 30% higher
3 Numbers in parentheses are the 95% Poisson confidence intervals

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Age specific death rates

The striking difference between Indigenous and non-Indigenous people in CVD mortality is the very much greater impact among young and middle aged Indigenous people. For all CVD, the death rates for Indigenous people were 12 to 17 times higher than those for non-Indigenous people in the 25-34 years and 35-44 years age groups (see rate ratios in Table 2). The age-specific death rates for Indigenous people in these age groups were similar to those among non-Indigenous people at least twenty years older.

Table 2: Age-specific death rates, by Indigenous status, and rate ratios, all cardiovascular diseases, WA, SA and NT, 1996-2000

Age category
Indigenous
Non-Indigenous
Rate ratios
Males
Females
Males
Females
Males
Females
<25
10
6
1
1
8.2
6.6
25-34
90
48
8
4
12.0
13.2
35-44
311
142
24
8
12.8
17.2
45-54
698
362
77
25
9.0
14.8
55-64
1,184
679
262
94
4.5
7.2
65-74
2,336
1,832
939
446
2.5
4.1
75+
4,355
3,723
3,843
3,385
1.1
1.1

Source: Derived from data provided by the AIHW National Cardiovascular Disease Database and ABS low series population projections
Notes:
1 Rates are per 100,000 population
2 Rate ratios are the Indigenous rates divided by the same-sex non-Indigenous rates
3 The rates and ratios in this table have not been adjusted for the likely under-identification of Indigenous people in deaths registration. Based on the estimated completeness of identification for WA, SA and the NT, the numbers and SMRs shown here could be up to 30% higher

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Trends in death rates

CVD death rates among the total Australian population have declined substantially since the late 1960s [8,9], but there is some evidence that these improvements were not shared by Indigenous people during the 1970s and 1980s [10].

A detailed analysis of trends in death rates over the period 1991-1996 found that overall mortality from CVD did not change for Indigenous males, at the same time as it decreased by 3.1% per year for non-Indigenous males [9]. In contrast, CVD mortality declined by 5.2% per year for Indigenous females and by 2.6% for non-Indigenous females.

Even more caution needs to be exercised in comparing these rates for Indigenous people with those for 1996-2000 that have been calculated separately, possibly using slightly different procedures. However, the rates for this later period are similar overall to those for 1991-1996, suggesting little real change in the impact of CVD among Indigenous people over the decade since 1991 (Table 3).

Table 3: Age-specific, crude and age-standardised death rates, Indigenous males and females, all cardiovascular disease, by year, WA, SA and NT, 1991-2000

Age category
1991
1992
1993
1994
1995
1996
1996-2000
M
F
M
F
M
F
M
F
M
F
M
F
M
F
<25
4
8
14
11
3
11
13
5
18
3
11
6
10
6
25-34
44
72
106
60
81
38
129
84
78
54
50
29
90
48
35-44
378
114
363
171
273
178
351
171
364
136
284
102
312
142
45-54
911
341
538
379
596
364
740
351
771
364
633
360
698
362
55-64
1,343
1,294
973
1,102
1,635
806
1,337
843
1,174
636
1,009
618
1,184
679
65-74
2,023
2,058
3,215
2,118
2,640
2,068
3,650
2,703
2,225
1,831
1,842
1,438
2,336
1,832
75+
3,462
3,889
1,955
2,970
2,946
3,647
4,780
5,222
4,622
3,025
3,348
2,725
4,356
3,723
Crude rate
230
190
199
177
203
165
251
194
220
138
178
125
213
155
Age-standardised rate
585
493
534
58
575
459
747
582
641
393
487
338
595
419

Sources: 1991-1996: Mathur & Gajanayake, 1998; 1996-2000: derived from data provided by the AIHW National Cardiovascular Disease Database and ABS low series population projections
Notes:
1 Great caution should be exercised in the interpretation of the rates in this table for two reasons: (i) The rates were calculated separately, possibly using slightly different procedures, and (ii) there may be differences in the Indigenous population figures from which the age-specific rates were calculated
2 Rates are per 100,000 population; the 1991 Australian population was used for estimation of age-standardised rates
3 M refers to Indigenous males; F refers to Indigenous females

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Hospitalisation

The much higher levels of mortality from CVD experienced by Indigenous people are partly reflected in hospitalisation rates [29]. In 2003-2004 across Australia, there were 7,260 hospital separations identified as Indigenous for 'diseases of the circulatory system', representing 3.4% of separations identified as Indigenous [29]. Hospitalisation rates were 1.2 times higher than for non-Indigenous people.

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Other evidence of CVD

The other recent source of information about CVD is the 2001 National Health Survey, in which information about health status, health-related actions and health risk factors was collected from around 3,700 Indigenous people from across Australia. More than one in six Indigenous males reported having a long-term cardiovascular condition, compared with 15% of non-Indigenous males (Table 4) [2]. Slightly more Indigenous females (21%) reported having a long-term cardiovascular condition, also around 1.2 times the proportion of non-Indigenous females reporting such a condition.

Table 4: Age-standardised proportions and ratios of self-reported cardiovascular disease, by Indigenous status and sex, Australia, 2001

Condition
Indigenous
Non-Indigenous
Ratios
Males
Females
Males
Females
Males
Females
Hypertension
12
16
9
10
1.3
1.6
Other CVD
11
8
11
11
1.0
0.7
All CVD
18
21
15
18
1.2
1.2

Source: (Australian Bureau of Statistics, 2002)
Note: The proportions have been standardised using the total Australian population at 30 June 2001 as the reference population

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Coronary heart disease

Mortality

The SMRs for coronary heart disease were 3.2 for males and 2.9 for females in WA, SA and the NT in 1996-2000 (Table 1). The very high rate ratios at young ages for all cardiovascular disease were as expected, seen also for the major specific group of cardiovascular disease, coronary heart disease (Table 5).

Table 5: Age-specific death rates, by Indigenous status, and rate ratios, coronary heart disease, WA, SA and NT, 1996-2000

Age category
Indigenous
Non-Indigenous
Rate ratios
Males
Females
Males
Females
Males
Females
<25
2
1
0
0
12.0
28.3
25-34
34
15
4
1
9.2
24.0
35-44
228
82
14
2
16.0
38.5
45-54
456
174
55
11
8.3
16.3
55-64
808
296
186
51
4.3
5.8
65-74
1,235
916
627
248
2.0
3.7
75+
1,813
1,599
2,151
1,633
0.8
1.0

Source: Derived from data provided by the AIHW National Cardiovascular Disease Database and ABS low series population projections
Notes:
1 Rates are per 100,000 population
2 Rate ratios are the Indigenous rates divided by the corresponding sex non-Indigenous rates. Being based on quite small numbers of deaths, particularly in the younger age groups, some caution should be exercised in the interpretation of these ratios
3 The rates and ratios in this table have not been adjusted for the likely under-identification of Indigenous people in deaths registrations. Based on the estimated completeness of identification for WA, SA and the NT, the numbers and SMRs shown here could be up to 30% higher

The trends in death rates from coronary heart disease reflect those of all CVD (Table 6). For the six-year period, 1991-1996, the age-standardised death rates for coronary heart disease decreased by 1.1% per year for Indigenous males (compared with 3.7% for non-Indigenous males) and by 7.0% for Indigenous females (compared with 3.7% for non-Indigenous females) [9]. The decreases for acute myocardial infarction, the major specific cause of death from coronary heart disease, mirror those for coronary heart disease - 2.6% for Indigenous males, 6.4% for non-Indigenous males, 6.1% for Indigenous females and 5.8% for non-Indigenous females.

Table 6: Age-specific, crude and age-standardised death rates, Indigenous males and females, coronary heart disease, by year, WA, SA and NT, 1991 2000

Age category
1991
1992
1993
1994
1995
1996
1996-2000
M
F
M
F
M
F
M
F
M
F
M
F
M
F
<25
8
0
0
0
0
0
0
0
3
0
0
0
2
1
25-34
11
21
42
30
31
10
89
19
29
0
20
21
34
15
35-44
206
0
248
47
145
59
305
28
248
55
176
48
228
82
45-54
558
199
453
216
433
104
502
226
514
170
438
84
456
174
55-64
697
626
730
734
1,154
524
812
321
657
238
641
289
808
296
65-74
852
1,152
1,330
883
1,650
1,031
1,659
1,395
809
955
900
830
1,235
916
75+
1,332
1,806
902
990
1,213
1,064
2,486
1,741
1,471
840
962
1,400
1,813
1,599
Crude rate
115
86
115
81
122
66
151
76
111
53
94
57
123
71
Age-standardised rate
277
239
291
207
342
191
417
234
286
150
242
164
332
198

Sources: 1991-1996: Mathur & Gajanayake, 1998; 1996-2000: derived from data provided by the AIHW National Cardiovascular Disease Database and ABS low series population projections
Notes:
1 Great caution should be exercised in the interpretation of the rates in this table for two reasons: (i) The rates were calculated separately, possibly using slightly different procedures, and (ii) there may be differences in the Indigenous population figures from which the age-specific rates were calculated
2 Rates are per 100,000 population; the 1991 Australian population was used for estimation of age-standardised rates
3 M refers to Indigenous males; F refers to Indigenous females

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Hospitalisation

The much higher levels of mortality from CVD experienced by Indigenous people are partly reflected in hospitalisation rates [11]. Across Australia in 1999-2000, Indigenous males were hospitalised for all CVD 1.5 times more frequently than non-Indigenous males, and Indigenous females were hospitalised 1.9 times more frequently than non-Indigenous females. The 3,390 separations of Indigenous males for CVD represented 4.7% of all separations for Indigenous males, and the 3,168 separations of Indigenous females was 3.2% of all separations for Indigenous females. Separation rates for CVD were higher for Indigenous people than for non-Indigenous people for virtually all age groups. The exceptions were females aged less than one year and males aged 75 years and older [12].

Details are not available for 2002-03, but hospitalisation rates for heart failure and coronary heart disease were between 1.5 and three times higher for Indigenous people than for non-Indigenous people in 2001-02 [30]. Indigenous males were more likely to be hospitalised for heart, stroke or vascular diseases than Indigenous females. Indigenous males were three times more likely to be hospitalised for these conditions than other Australian males, and Indigenous females were 1.7 times more likely than other Australian females [30].

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Stroke

Mortality

The SMRs for stroke were 3.3 for males and 2.4 for females in WA, SA and the NT in 1996-2000 (Table 1). The age pattern of deaths from stroke is similar to that for all cardiovascular disease and coronary heart disease: Indigenous:non-Indigenous rate ratios are highest in the young and middle age groups, with rates among Indigenous people being similar to those for non-Indigenous people around 20 years older (Table 7).

Table 7: Age-specific death rates, by Indigenous status, and rate ratios, stroke (cerebrovascular disease), WA, SA and NT, 1996-2000

Age category
Indigenous
Non-Indigenous
Rate ratios
Males
Females
Males
Females
Males
Females
<25
1
1
0
0
3.8
3.2
25-34
13
4
1
2
11.0
2.4
35-44
35
15
4
2
8.3
7.6
45-54
89
87
9
7
9.7
12.4
55-64
115
147
30
23
3.8
6.5
65-74
654
389
150
106
4.4
3.5
75+
1,400
1,094
865
988
1.6
1.1

Source: Derived from data provided by the AIHW National Cardiovascular Disease Database and ABS low series population projections
Notes:
1 Rates are per 100,000 population
2 Rate ratios are the Indigenous rates divided by the same-sex non-Indigenous rates
3 The rates and ratios in this table have not been adjusted for the likely under-identification of Indigenous people in deaths registration. Based on the estimated completeness of identification for WA, SA and the NT, the numbers and SMRs shown here could be up to 30% higher.

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Hospitalisation

Stroke was responsible for relatively few admissions among Indigenous people in 1999-2000 (288 male separations and 231 separations), but separation rates were around 1.6 those of non-Indigenous people [11]. A retrospective review of 86 Aboriginal patients admitted to a Perth teaching hospital in the five-year period 1988-1992 found that the mean age of the patients was 53 years [13]. Most strokes (67%) were ischaemic, with 20% due to spontaneous intracerebral haemorrhage, and 41% were due to presumed embolism from the heart. The prevalence of modifiable risk factors were relatively high (hypertension - 40%, smoking - 67%, hypercholesterolaemia - 60%, diabetes mellitus - 41%, alcohol abuse - 49% and atrial fibrillation - 22%).

Details are not available for 2002-03, but hospitalisation rates for heart failure and coronary heart disease were between 1.5 and three times higher for Indigenous people than for non-Indigenous people in 2001-02 [30]. Indigenous males were more likely to be hospitalised for heart, stroke or vascular diseases than Indigenous females. Indigenous males were three times more likely to be hospitalised for these conditions than other Australian males, and Indigenous females were 1.7 times more likely than other Australian females [30].

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Hypertensive disease

Very few data, other than that obtained through self-report, are available about hypertension, but 12% of Indigenous males reported in the 2001 NHS that they had the condition, compared with 9% of non-Indigenous males (Table 4) [2]. Around 16% of Indigenous females reported having hypertension, 1.6 times the proportion of non-Indigenous females reporting the condition.

The ratios of people reporting hypertension were higher generally in the younger age groups, with levels among Indigenous people being similar to non-Indigenous people aged some 10 years older (Table 8) [2]. The levels of hypertension reported by Indigenous people in the 2001 NHS were similar to those reported six years earlier in the 1995 NHS [4] and those documented in a 1988-1989 survey of 249 males and 241 females aged 15 years or older living in the Kimberley region of Western Australia [14].

The levels are considerably lower than the overall prevalence of 32% documented for 592 Torres Strait Islander people surveyed between 1993 and 1997 [15]. Around half of the survey participants aged 35 years or older were found to be hypertensive (defined as systolic blood pressure greater than or equal to 140mm Hg and/or diastolic blood pressure greater than or equal to 90mm Hg and/or person on anti-hypertensive medication). Only 5% of women aged 15-34 years had hypertension, but 18% of men in that age group were hypertensive.

Very similar levels were found among almost 2,900 Indigenous residents of north Queensland (including the Torres Strait Islands) who participated between March 1998 and December 2000 in well person's health checks: 49% of men and women aged 35 years or older were found to be hypertensive [16]. The prevalence of hypertension among people aged 15-34 years was 17% for males and 5% for females.

Table 8: Hypertension: age-specific proportions and ratios, by Indigenous status, Australia, 2001

Age category
Indigenous
Non-Indigenous
Rate ratio
15-24
1
1
1.0
25-34
5
1
5.0
35-44
10
4
2.5
45-54
25
14
1.8
55+
37
34
1.1

Source: (Australian Bureau of Statistics, 2002)

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Rheumatic fever and rheumatic heart disease

Mortality

Rheumatic fever and rheumatic heart disease are responsible for relatively few deaths, so the rates tend to fluctuate from year to year. The most recent data - for WA, SA and the NT in 1996-2000 - reveal that Indigenous males were 27 times and Indigenous females 23 times more likely to die from rheumatic fever and rheumatic heart disease than other Australians (Table 1). An analysis of deaths in the NT for 1979-1991 found that rheumatic heart disease accounted for 3% of all excess deaths in Indigenous males and 7% of all excess deaths in Indigenous females [17].

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Incidence and prevalence

Reflecting the continuing importance of rheumatic fever and rheumatic heart disease, particularly in the north of Australia, a register of known and suspected cases has been established in the NT. Data from this register reveal that the number of cases of acute rheumatic fever among 5-14 year old Indigenous children in the Top End of the Northern Territory declined from 254 per 100,000 population in 1988-1993 to 202 per 100,000 in 1994-1999 (Table 9) [1]. Overall, there were 528 people with rheumatic heart disease in the Top End in 1999. The prevalence of 1.33% is much higher than that among other Australians - 0.034%.

Table 9: Cases of acute rheumatic fever among Indigenous people, Top End of the Northern Territory, 1988-1999

Years
5-14 years
All ages
Number
Rate
Number
Rate
1988-1993
91
254
-
-
1994
18
204
27
84
1995
13
148
25
78
1996
21
238
38
105
1997
14
159
25
69
1998
24
270
36
101
1999
17
191
37
101
1994-1999
107
202
188
90

Source: (Australian Institute of Health and Welfare, 2002)

The incidence of rheumatic fever among Indigenous people in the Kimberley region of Western Australia is very similar to that for the Top End of the Northern Territory (Table 10) [18]. All of the 135 new cases occurring in the 15-year period 1982-1996 were among Indigenous people. Due to the relatively small numbers of new cases each year, the incidence tends to fluctuate considerably, but the three-year incidence for 1982-1984 was very similar to that for 1994-1996. In the Kimberley region, 111 of the 113 people with rheumatic heart disease were Indigenous - the prevalence was 0.87% among Indigenous people and 0.015% among non-Indigenous people [18].

Table 10: Incidence of acute rheumatic fever among Indigenous people, Kimberley region of Western Australia, 1982-1996

Age group (years)
Number
Rate
0-4
2
8
5-14
92
234
15-29
34
72
30-59
3
8
All ages
135
83

Source: (Mincham, 1999)
Notes:
1 Figures for ‘All ages’ includes four cases for which date of diagnosis, and hence age at diagnosis, was not available.
2 Rate is per 100,000 population.

For acute rheumatic fever and chronic rheumatic heart disease, hospitalisation rates for Indigenous males and females were six and eight times higher than for other Australians [30].

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Congenital heart disease

A review of notifications received by the Western Australian Birth Defects Registry for children born in Western Australia in the ten-year period 1980-1989 found that congenital heart disease was 30% more common among Indigenous than non-Indigenous children [19]. The overall level for Western Australia was similar to levels documented for other parts of the world.

Congenital heart defects with other defects were significantly more frequent in Indigenous than non-Indigenous children, but the excess of isolated heart defects was of borderline significance. The authors raise the possibility that the excess in congenital heart disease among Indigenous children may be due to genetic and environmental factors, the level of diabetes among Indigenous mothers, and foetal alcohol syndrome.

The only other relatively recent study has been for an Indigenous community in North Queensland for the seven-year period 1985-1991. This study reported a prevalence of congenital heart disease similar to the world-wide rate of six to eight per 1,000 live births [20].

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Prevention and management of cardiovascular disease

Much of the morbidity and mortality caused by CVD is preventable, in terms both of initial onset of the disease (primary prevention) and in managing and controlling established disease (secondary prevention and rehabilitation) [21]. Its preventability, along with the very high medical and other costs associated with CVD, has attracted substantial professional and government attention [21,8]. This attention has contributed to the advances in cardiovascular health seen in 'mainstream' Australia recently [1].

Primary prevention

The case for primary prevention of cardiovascular disease is supported by several lines of evidence which suggest that high levels of heart, stroke and vascular disease are not 'natural' and that, in principle, they can be changed considerably [21]. Modifiable risk factors, such as tobacco smoking, contribute to a large proportion of deaths from heart, stroke and vascular disease, and research has shown that when risk factors are reduced, so are the rates of heart, stroke and vascular disease.

Rheumatic heart disease represents a significant and entirely preventable cause of morbidity and mortality among Indigenous Australians, with organised primary health care essential for its control [21]. The real prevention of rheumatic fever (and its sequelae, rheumatic heart disease) involves improvements in socioeconomic conditions and housing, which should contribute to lower carriage and transmission of group-A streptococci, and reduce the need for the early detection and treatment with antibiotics to prevent rheumatic fever [22]. Social, economic and environmental conditions also need to be taken into consideration when assessing primary prevention strategies for coronary heart disease and stroke, as recent research has found correlations between social inequalities and the risks of death from all causes and cardiovascular disease [5]. Even after allowing for the traditional risk factors of smoking, obesity and physical inactivity, socioeconomic variables remained independently associated with the risk of death [23].

The fact that Commonwealth, State and Territory governments are not structured to deliver holistic care has been seen as a limiting aspect in this area [24]. With many areas affecting health - education, employment, social services, transport, etc. - being little influenced by the health sector, national health policies for Indigenous people may require much greater integration. Thus, there is considerable potential for reductions in the incidence of CVD among Indigenous Australians with committed application of the knowledge already available. As well as real action addressing the various 'behavioural' risk factors, attention needs to be directed also to the adverse social, economic and environmental conditions of many Indigenous people.

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Secondary prevention

Secondary prevention means interventions for people who have experienced a cardiovascular event (for example, a heart attack or stroke) and who are therefore at risk of another event [21].

Secondary prevention, including treatment with drugs (such as aspirin, beta-blockers and ACE inhibitors), has been shown to significantly reduce the risk of further events [21]. Secondary prevention also includes rehabilitation (to help patients return to an active life), continuing medical treatment (to reduce risk factor levels and control symptoms), and continuing attention to reducing levels of risk factors. The reduction of risk factors has an even greater potential for preventing cardiovascular events in those with established heart, stroke and vascular disease than in those without. Aspects of rehabilitation begin during the hospital stay, but the majority of rehabilitation occurs after discharge.

Secondary prevention and outpatient rehabilitation for CVD should be available to all patients in Australia, but this is not currently the reality [25]. It is therefore of utmost importance that Indigenous communities and health services are involved in the continual development of secondary prevention and rehabilitation programs for Indigenous people, particularly in rural and remote areas.

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Cardiac rehabilitation

Cardiac rehabilitation describes all measures used to help individuals with heart disease and associated risk factors return to an active and satisfying life, while preventing the recurrence of cardiac events [28]. (View background information on cardiac rehabilitation)

Indigenous participation in cardiac rehabilitation programs is less than desired [21]. Appropriate services are not available or accessible to all Indigenous patients with heart disease, especially those in remote or rural Australia. In addition, not all patients eligible for cardiac rehabilitation are offered a place, even when a program is available and accessible. Despite a recent increase in awareness of such issues, routine referral is still not standard practice and a proportion of patients who are referred do not attend (adequate data to assess this situation fully is unavailable). Among the many issues involved, rural and remote services need to be coordinated and the shortage of allied health staff acknowledged. A standardised data collection tool needs to be available in order to improve the current limited information regarding attendance at cardiac rehabilitation programs. Programs also need to be made more accessible and more attractive to Indigenous people to increase attendance [21].

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Stroke rehabilitation

A range of factors are associated with successful outcomes of stroke rehabilitation, but there is no standardised approach to identifying people who will benefit from rehabilitation [21]. The majority of strokes in the general population affect older people but, as noted above, rates among Indigenous people are similar to those for non-Indigenous people around 20 years older. It is acknowledged that stroke rehabilitation programs seldom meet the specific needs of younger patients, and this is likely to be particularly so for young Indigenous patients. Stroke can result in a sudden change in abilities, lifestyle and independence, especially for younger patients. Subsequently, the individual with stroke may react with a range of psychological responses, including depression. Depression and other psychological responses are also common in families of carers of people with stroke [26].

Stroke rehabilitation services available to Indigenous Australians vary greatly between geographical areas, with clustering in some areas and few or no services available in others (particularly rural and remote areas) [21]. Assessment procedures, management approaches and outcome measures vary between the services available, limiting effective communication between centres and impeding attempts to work towards best practice.

Despite the higher levels of mortality and morbidity associated with CHD and stroke in the Indigenous Australian population, programs for primary and secondary prevention, and rehabilitation are fragmented, and there are currently no clearly identified sources of funding for such programs at an appropriate scale [27]. The consequences are that efforts are insufficient to allow a real prospect of achieving the nationally agreed 10-year target of a 50 per cent reduction in mortality from coronary heart disease or of achieving the related targets for risk factors.

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Secondary prevention for rheumatic heart disease

The secondary prevention of rheumatic heart disease aims at the reduction of recurrences of rheumatic fever by utilising regular long-term prophylaxis with penicillin, the degree of protection varying directly with the level of prophylaxis achieved. Monthly intramuscular injections of benzathine penicillin have been recognised since the 1950s as the most effective regimen for patients at greatest risk of rheumatic recurrences [22]. The duration of treatment is dependent on the period since the most recent attack of rheumatic fever, the presence of chronic rheumatic heart disease, and living in a setting in which rheumatic fever is prevalent. For people with established rheumatic valvular disease, access to cardiac surgery may be important.

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Summary

CVD, particularly coronary heart disease, is the leading cause of death among Indigenous people. The available evidence suggests that the disparity between Indigenous and non-Indigenous people is widening, mainly because Indigenous people do not appear to have benefited from the substantial declines in coronary heart disease and stroke mortality that have occurred in Australia over the past thirty years. The declines for the total population have been attributed to a combination of reductions in the levels of various risk factors (including smoking, high blood pressure, and dietary saturated fats) and improvements in management of coronary heart disease and stroke events and established disease [1,21,8].

On the other hand, the failure to achieve substantial reductions in the impact of coronary heart disease and stroke among Indigenous people probably reflects a combination of little change in risk factor levels, poorer access of Indigenous people to treatment and rehabilitation services, and their persisting social, economic and environmental circumstances [24,1,21,27].

The situation is somewhat different for rheumatic fever/rheumatic heart disease. Australia's failure to alleviate the substandard social, economic and environmental conditions of many Indigenous communities underlies the persisting high incidence and prevalence of rheumatic fever/rheumatic heart disease among Indigenous people. With the persisting environmental risks, active primary prevention by way of screening for group A streptococcus and early antibiotic treatment remains important. Equally important is effective secondary prevention, involving prophylactic antibiotics, for those at risk of recurrent attacks of rheumatic fever.

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References

1. Australian Institute of Health and Welfare (2001) Heart, stroke and vascular diseases: Australian facts 2001. Canberra: Australian Institute of Health and Welfare
View report
2. Australian Bureau of Statistics (2002) National Health Survey: Aboriginal and Torres Strait Islander results. Canberra: Australian Bureau of Statistics
View report
3. Australian Bureau of Statistics (1996) National Aboriginal and Torres Strait Islander Survey 1994: health of Indigenous Australians. Canberra: Australian Bureau of Statistics, AGPS
View summary
4. Australian Bureau of Statistics (1999) National Health Survey: Aboriginal and Torres Strait Islander results. Canberra: Australian Bureau of Statistics
View report
5. Marmot M, Wilkinson R (2001) Psychosocial and material pathways in the relation between income and health: a response to Lynch et a l. British Medical Journal;322(7296):1233-1236
View paper
6. Bunker SJ, Colquhoun DM, Esler MD, et al. (2003) 'Stress' and coronary heart disease: psychosocial factors: National Heart Foundation of Australia position statement update. Medical Journal of Australia;178:272-276
View paper
7. Australian Bureau of Statistics, Australian Institute of Health and Welfare (2005) The health and welfare of Australia's Aboriginal and Torres Strait Islander peoples 2005. Canberra: Australian Bureau of Statistics, Australian Institute of Health and Welfare
View report
8. Mathur S (2002) Epidemic of coronary heart disease and its treatment in Australia. Canberra: Australian Institute of Health and Welfare
View report
9. Mathur S, Gajanayake I (1998) Surveillance of cardiovascular mortality in Australia 1985-96. Canberra: Australian Institute of Health and Welfare
View report
10. Kunitz SJ, Santow M, Streatfield R, De Craen A (1992) The health of populations of North Queensland Aboriginal communities: change and continuity. Canberra: The Australian National University
11. Lehoczky S, Isaacs J, Grayson N, Hargreaves J (2002) Hospital statistics. Aboriginal and Torres Strait Islander Australians. 1999-2000. Canberra: Australian Bureau of Statistics
View report
12. Australian Institute of Health and Welfare (2002) Australian hospital statistics 2000-01. Canberra: Australian Institute of Health and Welfare
View report
13. Crowley P, Hankey G (1995) Stroke among Australian Aboriginals in Perth, WA, 1988-1992. Australian and New Zealand Journal of Medicine;25:55
14. Smith RM, Spargo RM, Hunter EM, et al. (1992) Prevalence of hypertension in Kimberley Aborigines and its relationship to ischaemic heart disease. An age-stratified random survey. Medical Journal of Australia;156:557-562
15. Leonard D, McDermott R, O’Dea K, et al. (2002) Obesity, diabetes and associated cardiovascular risk factors among Torres Strait Islander people. Australian and New Zealand Journal of Public Health;26(2):144-149
16. Miller G, McDermott R, McCulloch B, Leonard D, Arabena K, Muller R (2002) The Well Person's Health Check: a population screening program in Indigenous communities in north Queensland. Australian Health Review;25(6):136-147
View abstract
17. Cunningham J, Condon JR (1996) Premature mortality in Aboriginal adults in the Northern Territory, 1979-1991. Medical Journal of Australia;165:309-312
18. Mincham C (1999) The quality of management of rheumatic fever and rheumatic heart disease in the Kimberley population. Perth, Western Australia: University of Western Australia
19. Bower C, Ramsay J (1994) Congenital heart disease: a 10-year cohort. Journal of Paediatric Child Health;30:414-418
20. Neilson G, Streatfield R, West M, Johnson S, Glavin W, Bird S (1993) Rheumatic fever and chronic rheumatic heart disease in Yarrabah Aboriginal community, north Queensland: establishment of a prophylactic program. Medical Journal of Australia;158:316-318
21. Commonwealth Department of Health and Aged Care, Australian Institute of Health and Welfare (1999) National health priority areas report: cardiovascular health 1998. Canberra: Australian Institute of Health and Welfare
View report
22. Stollerman GH (1997) Rheumatic fever. Lancet;349:935-942
23. Lantz P, House J, Lepkowski J, Williams D, Mero R, Chen J (1998) Socioeconomic factors, health behaviors, and mortality. Journal of the American Medical Association;279:1703-1708
View abstract
24. Anderson I (2000) Social determinants of Indigenous cardiovascular health. Paper presented at the Symposium on Indigenous cardiovascular health, Annual Scientific Meeting of the Cardiac Society of Australia and New Zealand. August 2000, Sydney, NSW
25. Commonwealth Department of Health and Aged Care, National Heart Foundation of Australia, James Cook University, National Aboriginal Community Controlled Health Organisation, National Rural Health Alliance (1999) Report of a national workshop on heart disease in Aboriginal people and Torres Strait Islanders and rural and remote populations. Townsville: James Cook University
26. Burvill P, Johnson G, Jamrozik K, Anderson C, Stewart-Wynne E, Chakera T (1995) Prevalence of depression after stroke: the Perth Community Stroke Study. The British Journal of Psychiatry;166:320-327
View abstract
27. Walsh WF (2001) Cardiovascular health in Indigenous Australians: a call for action [conference report]. Medical Journal of Australia;175:351-352
View paper
28. National Heart Foundation of Australia, Australian Cardiac Rehabilitation Association (2004) Recommended framework for cardiac rehabilitation 2004. Canberra: National Heart Foundation of Australia
View report
29. Australian Bureau of Statistics, Australian Institute of Health and Welfare (2005) The health and welfare of Australia's Aboriginal and Torres Strait Islander peoples 2005. Canberra: Australian Bureau of Statistics, Australian Institute of Health and Welfare
View report
30. National Centre for Monitoring Cardiovascular Disease (2004) Heart, stroke and vascular diseases: Australian facts 2004. Canberra: Australian Institute of Health and Welfare
View report

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Last updated: 4 September 2006