Review of Indigenous cardiovascular health

Introduction

Indigenous Australians ¹ experience poorer health outcomes than the non-Indigenous population [1] [2]. The Indigenous Australian population suffers a burden of disease two and a half times greater than other Australians [3]. Cardiovascular conditions are a major health problem for Indigenous Australians, and are more common among this population group than among the non-Indigenous population. Cardiovascular disease is the leading cause of premature death, and death overall, for all Australians. In 2009, it accounted for 32.8% of all deaths, and exceeded the health and economic burden of all other diseases in Australia [4]. During 2005-2007, cardiovascular disease was recorded as the cause of death for 1,810 Indigenous Australian deaths. After adjusting for the different age structures, the death rate for cardiovascular disease for Indigenous Australians was 1.4 times the rate of the non-Indigenous population [5].

Cardiovascular health incorporates the heart and circulatory system. The term cardiovascular disease refers to all diseases and conditions of this system; coronary (ischaemic) heart disease, heart failure, rheumatic heart disease, cerebrovascular disease (including stroke), peripheral vascular disease, hypertension (high blood pressure), and high blood cholesterol [5]. Cardiovascular diseases are caused by damage to the blood supply of the heart, brain, and/or legs, except for rheumatic heart disease, which is caused by acute rheumatic fever.

Cardiovascular disease among Indigenous Australians can be largely reduced through the modification of behavioural and biochemical risk factors [5]. Modifiable risk factors for this disease include smoking, alcohol, physical inactivity, nutrition, overweight and obesity, diabetes, high blood pressure and high blood cholesterol. Reducing the risk factors that predispose Indigenous Australians to cardiovascular disease can help to reduce the prevalence of this disease and its associated mortality.

Cardiovascular disease is a significant cause of hospitalisation for the Indigenous Australian population. In 2008-09, there were 8,826 hospitalisations for cardiovascular disease where the patient was identified as Indigenous² [6]. The rates for Indigenous people were almost twice that of the non-Indigenous population, 39.7 separations per 1,000 people compared with 20.6 separations respectively [6].

Indigenous people have substantially higher death rates than other Australians from most causes, including cardiovascular disease. Indigenous people are more likely to die from cardiovascular disease as non-Indigenous people, with the death rate ratios being particularly high for young and middle-aged adults [4] [7]. The leading cardiovascular conditions contributing to the higher mortality for Indigenous people are coronary (ischaemic) heart disease, cerebrovascular disease (including stroke) and hypertension. Rheumatic heart disease, now an uncommon cause of death for non-Indigenous Australians, still causes a considerable number of deaths in the Indigenous Australian population, primarily because of the persistence of acute rheumatic fever, especially in children.

Information on the trends of cardiovascular disease in Australia indicates that Indigenous people have not benefited to the same extent from the substantial declines in deaths rates seen among the non-Indigenous population [4] [7]. The continuing decline in overall death rates suggests that cardiovascular disease is largely preventable, and as such significant gains could be made for the Indigenous Australian population, particularly through the modification of risk factors.

This review focuses on the burden of cardiovascular disease for Indigenous Australians. It addresses overall prevalence, hospitalisation and mortality, and the factors contributing to this burden. The review provides information on a number of specific conditions including; coronary (ischaemic) heart disease, cerebrovascular disease (including stroke), hypertension, rheumatic heart disease (including acute rheumatic fever), and congenital heart disease. The review also looks at: the impact of cardiovascular conditions; costs and risk factors; as well as policies and strategies; and services.

Historical and socioeconomic context

The current health disadvantages experienced by Indigenous Australians can be linked to the social inequalities and historical atrocities they have experienced over time [8]. The cardiovascular health of Indigenous Australians was impacted by changes to their once active lifestyles and roles, brought about by displacement and the colonisation of European settlers. The health disadvantages of Indigenous people can be viewed as historical in origin [9], but remain embedded in the social foundations and materialised in the 'social determinants' of health measured today [10].

The historical context

Indigenous Australians adopted a hunter-gatherer lifestyle up until the late 18^th century. This incorporated the incidental physical activity involved with working the land for renewable food and resources, maintaining familial and cultural practices and sustaining the spiritual connection to country [9] cited in [11]. Their nutrition was sourced from the environment and used at a level for sustenance rather than producing excess surplus, this meant that activity was required on an ongoing basis to procure the resources needed for survival.

The arrival of the Europeans in 1788 changed the lifestyles of Indigenous Australians [11] [12]. The westernised economic system brought about industrialisation and agriculture of the land which took the natural resources away. This dispossession meant that Indigenous Australians had to rely on the provision of food by the Europeans and they were no longer able to work their ancestral land.

Physical activity levels and nutrition are modifiable risk factors for cardiovascular health and other chronic conditions; these were greatly impacted by the changes to the roles of Indigenous Australians [11] [13]. The reduction in activity levels of Indigenous Australians over time, paired with poor nutrition introduced by the Europeans, lead to an increase in cardiovascular disease and other chronic conditions, such as diabetes; and other health conditions, such as being overweight or obese, for this population group. Social and emotional wellbeing was also impacted by European settlement. This has now been recognised as a significant risk factor for cardiovascular disease among Indigenous Australians, and contributes to the higher prevalence among this population group.

The importance of contemporary social determinants and cultural concepts

Social determinants of health incorporate a holistic view of health on a broad scale. The importance of recognising this holistic approach to health is evident when considering specific health aspects such as cardiovascular disease. For Indigenous Australians, the concept of cardiovascular disease is not understood in the same way as other Australians. The traditional Indigenous Australian perspective of health, incorporates life, land, environment, physical body, community relationships and law, and is not seen as an isolated 'clinical' matter [11].

Westernised definitions and measurements of cardiovascular disease and associated risk factors may not be 'fitting' with the concepts of the Indigenous Australian population. Interventions such as new programs or projects targeting cardiovascular health for Indigenous Australians risk failure if they are based on westernised views of health rather than on the cultural concepts of health for this population group [11]. At a statistical level, cultural concepts of health may impact on data quality and coverage; self reporting and data collection measures could inaccurately record the level of cardiovascular disease for Indigenous Australians.

Extent of cardiovascular disease

Comparison data of the cardiovascular health of Indigenous Australians and non-Indigenous Australians should be viewed with a degree of caution as the data is derived from different data sources. The same caution can be applied when comparing the most recent measures of Indigenous cardiovascular health with those from previous data sources. This is for a number of reasons: improvements to data collection methods, including better identification of Indigenous Australians, may lead to increased accuracy and therefore can produce an amplification of figures which may be misleading [1]. Survey questions can be worded differently over time, which may lead to different interpretations of the question and can impact on final data outcomes.

Cardiovascular disease is a term used to encompass all of the major diseases of the heart and circulatory system. Risk factors for cardiovascular disease include biomedical and behavioural risk factors [14]. Apart from rheumatic heart disease (including acute rheumatic fever), which is specifically associated with poor living conditions, many of the cardiovascular diseases share common modifiable risk factors. These include: tobacco smoking; physical inactivity; poor nutrition; conditions of being overweight and obese; high blood pressure; high blood cholesterol and diabetes, among others. Many of these risk factors are largely preventable and if addressed could reduce the extent and burden of cardiovascular disease among Indigenous Australians. Other risk factors include socioeconomic factors and emotional wellbeing. Risk factors and the associated costs and burden are covered in more detail later in this review.

Incidence and prevalence

The most recent source of national information about the extent of cardiovascular disease among Indigenous Australians is the National Aboriginal and Torres Strait Islander Health Survey: Australia, 2004-05 (NATSIHS) [2]. Of Indigenous Australians surveyed in the NATSIHS, 12% reported a long-term heart or related condition, the proportion was slightly higher for those living in remote areas (14%) than in non-remote areas (11%).

A detailed analysis of the survey results were published in Cardiovascular disease and its associated risk factors in Aboriginal and Torres Strait Islander peoples 2004-05 which revealed that long-term heart and related conditions were 1.2 times more common for Indigenous males and 1.4 times more common for Indigenous females than their non-Indigenous counterparts (Table 1) [14]. Cardiovascular conditions were more common overall for Indigenous males and females than for non-Indigenous males and females, with hypertension being the most common cardiovascular condition among Indigenous Australians.

Table 1: Numbers, prevalence and ratios of cardiovascular conditions, Indigenous Australians, by sex and condition, Australia, 2004-05

Condition	Males			Females
	Number	Per cent	Ratio	Number	Per cent	Ratio
Source: Australian Institute of Health and Welfare, Penm E, 2008 [14]
Notes: Percentage of all Indigenous males and females Rates are per 1,000 Ratios are standardised prevalence ratios, the ratio of observed Indigenous numbers expected from the age-sex-cause specific prevalence for the non-Indigenous populations In view of the relatively small numbers involved, the estimates for cerebrovascular disease, heart failure and rheumatic heart disease should be interpreted with caution
Coronary/ischaemic heart disease	2,800	1.2	1.7	3,000	1.2	2.7
Cerebrovascular disease (including stroke)	700	0.3	1.5	700	0.3	1.9
Heart failure	1,400	0.6	1.9	3,100	1.3	1.6
Hypertension	15,000	6.4	1.5	18,700	7.7	1.7
Rheumatic heart disease	900	0.4	n/a	2,600	1.1	n/a
Other conditions	1,200	0.5	n/a	5,800	2.4	n/a
All CVD	22,000	9.5	1.2	33,900	14	1.4

Cardiovascular conditions were noted more commonly for Indigenous Australians than the non-Indigenous Australian population across all age groups. Given the relatively younger age structure of the Indigenous Australian population, the prevalence of these conditions in the 35-44 years age group (21%) was similar to those in the 45-54 years age group for the non-Indigenous population (Table 2) [2]. Rates for cardiovascular conditions for Indigenous Australians in the 35-44 years age group were almost double that of the non-Indigenous population, 21% compared with 12% respectively.

Table 2: Prevalence of cardiovascular conditions, by Indigenous status and selected age groups, Australia, 2004-05

Condition	Age groups
	35-44 years		45-54 years		55 years and over
	Indigenous	Non-Indigenous	Indigenous	Non-Indigenous	Indigenous	Non-Indigenous
	Prevalence (%)		Prevalence (%)		Prevalence (%)
Source: Australian Bureau of Statistics, 2008 [2]
Notes: Sum of components may be more than total as persons may have reported more than one type of condition
Hypertension	12	4	22	14	42	33
Other cardiovascular diseases	12	8	16	11	28	26
Total	21	12	31	22	54	48

Age specific rates for cardiovascular disease were higher among Indigenous people across all adult age groups than the non-Indigenous population. The greatest disparity was in the 45-54 years age group for Indigenous females 286.0 per 1,000 compared to 196.0 for non-Indigenous females; 55-64 years age groups for Indigenous males 606.0 compared to 391.6 for non-Indigenous males; and for both sexes, 55-64 years age group with 498.7 Indigenous rates compared with 367.6 non-Indigenous rates [14].

The most common cardiovascular conditions for Indigenous people were hypertension (7.1%), coronary (ischaemic) heart disease (1.2%), heart failure (1.0%), rheumatic heart disease (0.7%) and cerebrovascular disease (including stroke) (0.3%) [14]. After adjusting for the age structure differences in these two population groups, the greatest disparity in prevalence was seen for coronary (ischaemic) heart disease, with Indigenous rates 2.1 times the non-Indigenous rates. This was followed by rates for cerebrovascular disease (including stroke) and heart failure at 1.7 times greater, and hypertension 1.6 times greater among the Indigenous population [14].

Hospitalisation

The higher prevalence of cardiovascular disease for the Indigenous Australian population is to some extent reflected in hospitalisation rates³ [3] [15]. There were 9,149 episodes of hospitalisation for diseases of the circulatory system for Indigenous Australians in 2009-10 [15]. In 2008-09, this rate was 1.9 times that of non-Indigenous people⁴ [6]. Separation rates for cardiovascular disease were 39.7 per 1,000 for Indigenous Australians compared with 20.6 for non-Indigenous Australians. For congestive heart failure, in 2008-09, separation rates for Indigenous Australians were 6.1 per 1,000, and non-Indigenous Australians 2.0 [16]. In 2007-08, the rates of hospitalisations for cardiovascular disease were higher among Indigenous people than non-Indigenous people, 1.5 times higher for males, and 1.9 times higher for females [5].

The more detailed data available for the two-year period July 2004 to June 2006 were similar overall, with the number of episodes of hospitalisation for Indigenous males 1.9 times the number expected from the age-cause-specific rates for non-Indigenous males, and the number for Indigenous females, 2.3 times greater than the number expected from the age-cause-specific rates for non-Indigenous females [3]. Overall circulatory conditions made up 3% of all hospitalisation of Indigenous people during this time period [7], of those 53% were males and 47% females. Of all Indigenous hospitalisations for circulatory conditions, 43% were for coronary (ischaemic) heart disease at a rate of between two and three times that of the non-Indigenous population; and approximately 30% of hospitalisations were for other heart diseases. Rheumatic heart disease accounted for a large proportion of the hospitalisation disparity, with Indigenous rates between five (males) and nine (females) times higher than the non-Indigenous rates. Rates of Indigenous hospitalisation for hypertension were also higher among the Indigenous population with a rate four times that of other Australians.

Table 3: Numbers, rates and ratios of hospitalisation of Indigenous Australians for cardiovascular conditions, by sex and disease category, Australia, 2004-06

Condition	Males			Females
	Number	Per cent	Ratio	Number	Per cent	Ratio
Source: Australian Institute of Health and Welfare, 2008 [7]
Notes: Categories are based on the ICD-10-AM. Figures shown in italics (acute myocardial infarction and stroke) are sub-categories of the categories immediately above Rates are per 1,000 Rates are directly age-standardised rates using the 2001 Australian standard population Ratios are the numbers of hospitalisations of Indigenous males and females divided by the number expected from the age-sex-cause specific rates for non-Indigenous people. All ratios are significant at the p<0.05 level Data from NSW, Vic, Qld, WA, SA and the NT
Coronary (ischaemic) heart disease	3,778	17.7	1.7	2,820	12.8	2.7
Acute myocardial infarction	1,468	6.8	2.1	978	4.3	3.4
Pulmonary & other forms of heart disease	2,352	12.2	1.7	2,207	10.5	2.1
Cerebrovascular disease	633	3.7	1.6	651	3.1	2.1
Stroke	572	3.4	1.9	575	2.7	2.2
Rheumatic heart disease	229	0.9	3.4	359	1.5	4.0
Other conditions	808	3.4	0.6	791	3.0	0.6
All CVD	8,041	38.3	1.5	7,273	32.8	2.0

Hospitalisation rates for cardiovascular disease, for the period 2004-06⁵, increased with age for both the Indigenous and non-Indigenous population groups, with higher rates recorded for Indigenous Australians than for non-Indigenous Australians across all age groups (Figure 1) [14]. The hospitalisation rates for Indigenous females were higher than their non-Indigenous counterparts across all age groups; the largest disparity occurred in the 35-44, 45-54, and 55-64 year age groups, with rates for Indigenous females approximately three times the rate of non-Indigenous females. For Indigenous males, hospitalisation rates were higher than non-Indigenous males in all age groups, apart from the 65+ years age group; the greatest disparity occurring in the 5-14, 35-44 and 45-54 year age groups, with rates of between two and three times higher among Indigenous males.

Figure 1 Hospitalisation rates for cardiovascular disease, by Indigenous status and age group, persons, Australia, 2004-06

Source: Australian Institute of Health and Welfare, 2008 [7]
Note:

1. Rates are per 1,000 population
2. Data from NSW, Vic, Qld, WA, SA and the NT

 

In 2008-09, procedures for cardiovascular conditions were also higher in the Indigenous population with a count of 10,442. Age standardised rates for Indigenous Australians were 38.1 per 1,000, a rate 1.5 times that of the non-Indigenous population (25.4) [6]. Cardiovascular procedures made up 2.8% of all Indigenous hospital procedures for this time period.

Mortality

In 2009, cardiovascular disease was the leading cause of death for Indigenous people, accounting for 620 Indigenous deaths and 25.8% of all Indigenous deaths [4]. Coronary (ischaemic) heart disease and cerebrovascular disease (including stroke) made up the two most commonly reported circulatory diseases accounting for these deaths.

Coronary (ischaemic) heart disease contributed to 369 Indigenous deaths (15.3%), and was also the leading cause of death for non-Indigenous Australians, accounting for 16% of deaths across Australia [4]. Deaths of Indigenous males from this disease were more common than Indigenous females, with a sex ratio of 1.49. The median age of Indigenous Australians who died from coronary (ischaemic) heart disease was 58.1 years compared to 84.2 years for non-Indigenous Australians.

Cerebrovascular disease (including stroke) contributed to 96 Indigenous deaths or 4%, and among the non-Indigenous population accounted for 8.1% of deaths [4]. Unlike coronary heart disease, there were no differences in the sex ratio for these deaths. The median age of death however was again lower in the Indigenous population (68.3 years) than in the non-Indigenous population (85.6 years).

The more detailed data available for the four-year period 2001 to 2005 showed that the number of Indigenous deaths from cardiovascular disease was more than three times the number expected from the rates for the non-Indigenous population⁶ [3].

Table 4: Rates of death from selected cardiovascular diseases, by Indigenous status, and Indigenous:non-Indigenous rate ratios, people aged 35-54 years, Qld, WA, SA and the NT, 2001-2005

Condition	Indigenous		Non-Indigenous		Rate ratio
	Males	Females	Males	Females	Males	Females
Source: Australian Bureau of Statistics, Australian Institute of Health and Welfare, 2008 [3]
Notes: Categories are based on the ICD-10-AM. ICD codes are in parentheses. Rates are per 1,000 Ratios are the Indigenous rates divided by the non-Indigenous rates.
Coronary (ischaemic) heart disease	227.7	87.1	32.3	6.1	7.0	14.2
Other selected forms of heart disease	45.7	21.8	5.6	2.0	8.1	10.8
Cerebrovascular disease	28.3	24.4	5.5	4.7	5.1	5.2

The leading specific cause of death for both Indigenous males and females in 2002-05 was coronary (ischaemic) heart disease, for which there were approximately three times as many deaths than expected (Table 4) [3]. The ratio of the number of deaths observed to the number expected is known as the standardised mortality ratio (SMR). For cerebrovascular disease (including stroke), the SMR was 2.1 for Indigenous males and 1.8 for Indigenous females. Rheumatic heart disease was responsible for relatively few deaths, but the SMR was 15.1 for Indigenous males and 23.0 for Indigenous females.

Table 5: Numbers of Indigenous deaths from cardiovascular disease and standardised mortality ratios (SMRs), by sex, Qld, WA, SA, and the NT, 2002-2005

Cause of death	Males		Females
	Number	SMR	Number	SMR
Source: Australian Institute of Health and Welfare, 2008 [7]
Notes: ICD codes for specific forms of CVD are shown in parentheses. 'Cerebrovascular disease' includes stroke The numbers shown here have been derived from annual averages, so may differ slightly from actual numbers. The SMR is the ratio of the numbers of deaths observed to the numbers expected from the age-sex-cause specific rates for the non-Indigenous populations.
Coronary (ischaemic) heart disease	564	3.3	332	2.8
Cerebrovascular disease (including stroke)	112	2.1	132	1.8
Heart failure	16	2.0	28	2.4
Rheumatic heart disease	20	15.1	52	23.0
Other conditions	152	3.0	140	3.1
All CVD	864	3.1	684	2.7

Age-specific death rates

Mortality from cardiovascular disease occurs in much younger age groups among Indigenous Australians, than among the non-Indigenous population, particularly among young and middle-aged Indigenous adults. For all cardiovascular conditions, the death rates in 2002-2005, in the 35-44 and 45-54 age groups, were 7 to 12 times higher for Indigenous people than those for non-Indigenous people (Figure 2) (Figure 3) [14]. The death rates for Indigenous people in these age groups were similar to those for non-Indigenous people approximately 20 years older.

Figure 2 Death rates for cardiovascular disease, by Indigenous status and age group, males, Qld, WA, SA and the NT, 2002-2005

Source: Australian Institute of Health and Welfare, Penm E, 2008 [14]
Note:

1. Rates are per 100,000 population

 

Figure 3 Death rates for cardiovascular disease, by Indigenous status and age group, females, Qld, WA, SA and the NT, 2002-2005

Source: Australian Institute of Health and Welfare, Penm E, 2008 [14]
Note:

1. Rates are per 1,000 population

 

Coronary (ischaemic) heart disease

Coronary (ischaemic) heart disease refers to conditions of the blood vessels that supply blood to the heart muscle [14]. The main conditions include acute myocardial infarction and angina. Myocardial infarction occurs when the blood flow to the heart is stopped, usually when a coronary artery becomes completely blocked. When a blockage occurs, the heart muscle may become damaged or start to die off, thus reducing its ability to function. The longer the blockage is present, the more damaging it is to the heart muscle. This damage cannot be undone, and can result in death. Angina refers to a severe yet partial blockage which temporarily reduces blood flow to the heart. This condition causes temporary chest pain and is usually not life threatening, however those who experience angina are more likely to suffer myocardial infarction than those without this condition.

Of all cardiovascular diseases, coronary (ischaemic) heart disease is the most common among Indigenous Australians [14]. Indigenous Australians experience this disease at a rate more than twice that of non-Indigenous Australians, and more frequently among younger age groups. Of those Indigenous Australians with coronary (ischaemic) heart disease, approximately two thirds had experienced angina, and one third had experienced an acute myocardial infarction. It is the single greatest cause of mortality and contributes to the most premature and unnecessary deaths.

In 2004-05, coronary (ischaemic) heart disease was reported as a long-term condition by 2,800 Indigenous males and 3,000 Indigenous females (Table 1) [14]. These levels were 1.7 times higher than those for non-Indigenous males and 2.7 times higher than those for non-Indigenous females [14]. The differences between Indigenous Australians and non-Indigenous Australians were the greatest among the 25-44 year age group with a rate ratio of 3.4 (Table 6) [14].

Table 6: Prevalence of coronary (ischaemic) heart disease, Indigenous Australians by sex and selected age groups, Australia, 2004-05

Sex	Age groups
	25-44 years	45-64 years	65 years +
Australian Institute of Health and Welfare, Penm E, 2008 [14]
Notes: Based on self reported data from the NATSIHS, 2004-05.
Males
Percent (%)	1.1	4.3	15.3
Rate ratio	2.9	1.6	1.4
Females
Percent (%)	0.6	6.4	7.2
Rate ratio	5.5	5.1	1.0
Persons
Percent (%)	0.9	5.4	10.8
Rate ratio	3.4	2.8	1.2

There were over 6,500 admissions of Indigenous Australians to hospital for coronary (ischaemic) heart disease in the two-year period 2004- 06 (Table 3) (Table 7) [7]. Of these admissions, almost 2,450 were for acute myocardial infarction. Admission rates for Indigenous Australians for coronary (ischaemic) heart disease were 2.0 times higher than non-Indigenous Australians and for acute myocardial infarction 2.5 times higher than the corresponding rates for non-Indigenous people.

Table 7: Hospitalisations of Indigenous Australians for coronary (ischaemic) heart disease, by sex, Australia, 2004-06

Sex	Condition
	Acute myocardial infarction	All coronary (ischaemic) heart disease
Source: Australian Institute of Health and Welfare, 2008 [7]
Notes: Rates are per 1,000 Rates are directly age-standardised using the 2001 Australian standard population. Rate ratio is the Indigenous rate divided by the non-Indigenous rate. All ratios are significant at the p<0.05 level. Data from NSW, Vic, Qld, WA, SA and the NT.
Male
Number	1468	3778
Percent (%)	18.3	47.0
Rate	6.8	17.7
Rate ratio	2.1	1.7
Female
Number	978	2820
Percent (%)	13.4	38.8
Rate	4.7	12.8
Rate ratio	3.4	2.7
Total
Number	2446	6598
Percent (%)	16.0	43.1
Rate	5.7	15.1
Rate ratio	2.5	2.0

Coronary (ischaemic) heart disease remains the leading cause of death for Indigenous Australians. In 2009, there were 369 deaths (15.3%), approximately 17% of male and 13% of female Indigenous deaths were recorded [4]. The highest overall levels of deaths from coronary (ischaemic) heart disease were recorded in NSW with 106 deaths (17.9%).

For the period 2002-2006, coronary (ischaemic) heart disease accounted for 1,141 Indigenous deaths or 56.8% of all Indigenous cardiovascular deaths (Table 8) [7]. Acute myocardial infarction accounted for 541 of these deaths, or 26.9% of all Indigenous cardiovascular deaths.

Table 8: Deaths of Indigenous Australians for coronary (ischaemic) heart disease, by sex, Qld, WA, SA and NT, 2002-2006

Sex	Condition
	Acute myocardial infarction	All coronary (ischaemic) heart disease
Source: Australian Institute of Health and Welfare, 2008 [7]
Notes: Rates are per 1,000 Rates are directly age-standardised using the 2001 Australian standard population. Rate ratio is the Indigenous rate divided by the non-Indigenous rate. All ratios are significant at the p<0.05 level. Data from NSW, Vic, Qld, WA, SA and the NT.
Male
Number	349.0	714.0
Percent (%)	30.9	63.3
Rate	136.3	277.1
Rate ratio	1.8	1.9
Female
Number	192.0	427.0
Percent (%)	21.8	48.5
Rate	84.4	173.5
Rate ratio	1.6	1.8
Total
Number	541.0	1141.0
Percent (%)	26.9	56.8
Rate	1086	221.3
Rate ratio	1.7	1.9

Standardised mortality ratios (SMRs) for coronary (ischaemic) heart disease for Indigenous people living in Qld, WA, SA and the NT in 2002-2005 were 3.3 for males and 2.8 for females (Table 5) [7]. An analysis of selected causes of death from cardiovascular disease⁷ found that the rate for Indigenous people for coronary (ischaemic) heart disease was 4.6 times the rate for non-Indigenous people (Table 8) [7].

Full details of deaths from coronary (ischaemic) heart disease are not available for all age groups, but the rates were much higher for Indigenous people aged 35-54 years living in Qld, WA, SA and the NT in 2002-2005 than for their non-Indigenous counterparts (Table 4) [3]. The largest number of excess deaths occurred in this age group, and approximately 40% of these Indigenous Australian deaths would have been avoided if they had the same deaths rates as non-Indigenous Australians [17].

Age specific rate ratios for mortality, admissions and procedures for coronary (ischaemic) heart disease for Indigenous Australians and non-Indigenous Australians in Qld revealed the highest differences in mortality and admission rates was in the 30-39 year age group, with Indigenous rates higher than non-Indigenous rates (Table 9) [18]. The differences in rates declined through each increase in age group until the 80+ year age group where the Indigenous morality rates became slightly lower than the non-Indigenous rates. Procedure rates remained lower for Indigenous Australians across all age groups, despite the relatively higher admission rates. The differences in the procedure rates between the population groups increased with each increase in age group. These figures give some indication of the outcomes for Indigenous Australians suffering from coronary (ischaemic) heart disease, and highlight the relatively low levels of procedures rates despite the much greater levels of admissions for this population group.

Table 9: Coronary (ischaemic) heart disease events, Indigenous:non-Indigenous age specific rate ratios, Qld, 2003-2008

Age group	Age specific rate ratios
	Mortality	Admission	Procedure
Source: Webster, 2010 [18]
Notes: Mortality data is from 2003-2007 and admissions and procedures data is from 2004-2008.
30-39	8.66	7.54	0.91
40-49	7.54	4.59	0.67
50-59	4.88	3.14	0.5
60-69	3.6	2.26	0.49
70-79	1.96	1.76	0.45
80+	0.87	1.15	0.28

Cerebrovascular disease

Cerebrovascular disease refers to conditions of the blood vessels that supply blood to the brain [14]. The main conditions include stroke and transient ischaemic attack. Stroke, the most common condition, has two main forms: ischaemic stroke and haemorrhagic stroke. Ischaemic stroke occurs when the blood flow to the brain is stopped, usually due to a blood clot or the build up of cholesterol. Haemorrhagic stoke occurs when a blood vessel ruptures and bleeds within the brain. When a blockage or rupture occurs, oxygen to the brain is interrupted, and parts of the brain may become damaged or start to die off, thus reducing its ability to function. The longer the blockage is present, the more damaging it is to the brain. This damage cannot be undone, and can result in the loss of sensory and motor functions, brain damage or death. Ischaemic stroke is up to five times more common than haemorrhagic stroke, however the disability and fatality rates associated with haemorrhagic stroke are much higher.

Transient ischaemic attack is a less severe form of stoke and refers to the temporary reduction of oxygen flow to the brain [14]. This condition causes temporary symptoms such as impairment to brain functioning, and is usually not life threatening.

Indigenous Australians experience cerebrovascular disease at a rate almost twice that of the non-Indigenous population [14]. Cerebrovascular disease is more common among younger Indigenous Australians than non-Indigenous Australians. The majority of cerebrovascular disease in the Indigenous population was among the 25-64 year age groups (80%) and cerebrovascular disease in teh non-Indigenous population was more common in those among the 65 and over year groups (66%) [14].

In 2004-05, cerebrovascular disease was reported as a long-term condition by 700 Indigenous Australian males and by 700 Indigenous Australian females (Table 1) [14]. These levels were 1.5 and 2.9 times higher than those for non-Indigenous Australian males and females. The standardised prevalence ratio shows that 0.3% of Indigenous Australians experience cerebrovascular disease, a level 1.7 times higher than non-Indigenous Australians (Table 10) [14].

Table 10: Prevalence of cerebrovascular disease, Indigenous Australians by sex, Australia, 2004-05

Sex	Percent (%)	SPR
Source: Australian Institute of Health and Welfare, Penm E, 2008 [14]
Notes: Based on self reported data from the NATSIHS, 2004-05. Standardised prevalence ratio (SPR) is the ratio of observed cases to expected cases if the Indigenous population experienced the same age-sex specific prevalence rates as the non-Indigenous population
Males	0.3	1.5
Females	0.3	1.9
Total	0.3	1.7

There were almost 1,300 admissions of Indigenous Australians to hospital for cerebrovascular disease in the two-year period 2004-06 (Table 3) (Table 12) [7]. Of these admissions, almost 1,150 were for stroke. Admission rates for Indigenous Australians for cerebrovascular disease were 3.6 times higher than non-Indigenous Australians and for stroke 3.2 times higher than the corresponding rates for non-Indigenous people.

Table 11: Hospitalisations of Indigenous Australians for cerebrovascular disease, by sex, Australia, 2004-06

Sex	Condition
	Stroke	All cerebrovascular disease
Source: Australian Institute of Health and Welfare, 2008 [7]
Notes: Rates are per 1,000. Rates are directly age-standardised using the 2001 Australian standard population Rate ratio is the Indigenous rate divided by the non-Indigenous rate. All ratios are significant at the p<0.05 level Data from NSW, Vic, Qld, WA, SA and the NT
Male
Number	572	633
Percent (%)	7.1	8.0
Rate	3.4	3.7
Rate ratio	1.9	1.6
Female
Number	575	651
Percent (%)	7.9	9.0
Rate	3.0	3.4
Rate ratio	2.2	2.1
Total
Number	1,147	1,284
Percent (%)	7.5	8.4
Rate	3.2	3.6
Rate ratio	2.0	1.9

Deaths rates for Indigenous Australians from cerebrovascular disease are at a rate almost twice that of non-Indigenous Australians, and occur more frequently among younger age groups [14]. In 2009, cerebrovascular disease accounted for 96 deaths (4.0%), approximately 3.5% of male and 4.4% of female Indigenous deaths were recorded [4]. The highest overall levels of deaths from coronary (ischaemic) heart disease were recorded in NSW with 32 deaths (5.4%).

For the period 2002-2006, cerebrovascular disease was the second leading cause of cardiovascular deaths for Indigenous Australians, accounting for 330 deaths or 16.4% of all Indigenous cardiovascular deaths (Table 12) [7]. Strokes accounted for 272 of these deaths, or 13.5% of all Indigenous cardiovascular deaths.

Table 12: Deaths of Indigenous Australians for cerebrovascular disease, by sex, Qld, WA, SA and NT, 2002-2006

Sex	Condition
	Stroke	All cerebrovascular disease
Source: Australian Institute of Health and Welfare, 2008 [7]
Notes: Rates are per 1,000. Rates are directly age-standardised using the 2001 Australian standard population Rate ratio is the Indigenous rate divided by the non-Indigenous rate. All ratios are significant at the p<0.05 level
Male
Number	126	157
Percent (%)	11.2	13.9
Rate	65.6	86.3
Rate ratio	1.7	1.7
Female
Number	146	173
Percent (%)	16.6	19.7
Rate	66.5	83
Rate ratio	1.5	1.5
Total
Number	272	330
Percent (%)	13.5	16.4
Rate	66.4	84.7
Rate ratio	1.6	1.5

Standardised mortality ratios (SMRs) for cerebrovascular disease for Indigenous people living in Qld, WA, SA and the NT in 2002-2005 were 2.1 for males and 1.8 for females (Table 6) [3]. An analysis of selected causes of death from cardiovascular disease⁸ found that the rate for Indigenous people for cerebrovascular disease was 1.5 times the rate for non-Indigenous people (Table 12) [7].

Full details of deaths from cerebrovascular disease are not available for all age groups, but the rates were much higher for Indigenous people aged 35-54 years living in Qld, WA, SA and the NT in 2002-2005 than for their non-Indigenous counterparts (Table 4) [3]. Both Indigenous male and female death rates increased with every increase in age group however the patterns of increase between the two sexes were different. Indigenous male death rates increased progressively whereas Indigenous female death rates increased less rapidly with age, until the 65 and over year group, where there was a marked increase in rates [14]. Overall, in the 25-64 years age groups, both Indigenous males and females experienced higher rates than their non-Indigenous counterparts as much as three to eight times for males, and four to seven times as high for females.

Hypertension

Hypertension refers to the elevation of blood pressure over a prolonged period of time [14]. This pressure is the force of the blood on the walls of the blood vessels and is measured by systolic and diastolic blood pressure. Systolic blood pressure is a measurement when the heart muscle contracts to pump blood, the highest pressure in the arteries; and diastolic blood pressure is a measurement when the heart muscle relaxes, the lowest pressure in the arteries. High blood pressure causes the heart to work harder, and can cause damage to the heart muscle, making the muscle weak and enlarged.

Among Indigenous Australians, hypertension is a common form of cardiovascular disease affecting approximately 33,600 people; 6.4% of Indigenous males and 7.7% of Indigenous females reported having hypertension as a long-term condition (Table 1) [14]. Hypertension was more commonly reported by Indigenous people living in remote areas (10%) than those living in non-remote areas (6%) [2].

The proportions of Indigenous people reporting hypertension as a long-term condition were higher than those of non-Indigenous people for all age groups (Figure 4) [14].

Figure 4 Reported proportions of hypertension, by Indigenous status and age group, Australia, 2004-2005

Source: Australian Institute of Health and Welfare, Penm E, 2008 [14]
Note:

1. Based on self reported data from the NATSIHS, 2004-05

 

The prevalence of hypertension among Indigenous Australians is higher than the non-Indigenous population across all age groups (Figure 4) [14]. After adjusting for differences in the age structures of the Indigenous population and the non-Indigenous population, prevalence rates for Indigenous males were 1.5 times that of non-Indigenous males, and for Indigenous females 1.7 times that of non-Indigenous females (Table 1) [14]. The prevalence of hypertension increased with each increase in age group for both the Indigenous and non-Indigenous population [7].

The highest differences in the prevalence of hypertension between the Indigenous population and non-Indigenous population were seen in the younger age groups (Table 2) (Figure 4) [14] [2]. Indigenous males aged 25-44 years had a rate 2.2 times higher than non-Indigenous males, and Indigenous female in the 25-44 years age group had a rate 2.8 times higher than non-Indigenous females (Table 13) [14].

Table 13: Prevalence of hypertension, Indigenous Australians by sex, selected age groups, Australia, 2004-05

Sex	Age groups
	25-44 years	45-64 years	65 years +
Source: Australian Institute of Health and Welfare, Penm E, 2008 [14]
Notes: Based on self reported data from the NATSIHS, 2004-05. Rate ratio is the Indigenous rate divided by the non-Indigenous rate. All ratios are significant at the p<0.05 level
Males
Percent (%)	8.4	25.0	44.2
Rate ratio	2.2	1.3	1.2
Females
Percent (%)	7.4	30.4	49.3
Rate ratio	2.8	1.6	1.2
Persons
Percent (%)	7.8	27.8	47.1
Rate ratio	2.5	1.5	1.2

In the jurisdictions of NSW, Vic, Qld, WA, SA and the NT, there were almost 600 admissions of Indigenous Australians to hospital for hypertension in the two-year period 2004-06 (Table 3) (Table 14) [7]. Admission rates for Indigenous Australians for hypertension were 3.8 times higher than non-Indigenous Australians. Rates for Indigenous males were 3.4 times higher and Indigenous females were 4.0 times higher than their non-Indigenous counterparts.

After adjusting for Indigenous under-identification, Indigenous hospitalisation rates for hypertension were 4.1 times the rate of non-Indigenous hospitalisations (Table 14) [7]. The rate ratios increased by 0.2 for males and 0.3 for females, from the non-adjusted figures.

Table 14: Hospitalisations of Indigenous Australians for hypertension, by sex, Australia, 2004-06

Sex	Indigenous status
	Indigenous			Non-Indigenous
	NSW, Vic, Qld, WA, SA & NT	Australia unadjusted	Australia adjusted	NSW, Vic, Qld, WA, SA & NT	Australia unadjusted	Australia adjusted
Source: Australian Institute of Health and Welfare, 2008 [7]
Notes: Rates are per 1,000. Rates are directly age-standardised using the 2001 Australian standard population. Rate ratio is the Indigenous rate divided by the non-Indigenous rate. Non-Indigenous figures include those where Indigenous status was not recorded. Australia unadjusted data includes all eight states and territories. Australia adjusted data includes all eight states and territories and has been adjusted for Indigenous under identification.
Males
Number	229	230	257	4,956	5,129	5,102
Percent (%)	2.8
Rate	0.9	0.8	0.9	0.3	0.3	0.3
Rate ratio	3.4	3.2	3.6
Females
Number	359.0	359	401	8,437	8,721	8,679
Percent (%)	4.9
Rate	1.5	1.5	1.6	0.4	0.4	0.4
Rate ratio	4.0	3.9	4.3
Persons
Number	588.0	589	658	13,394	13,851	13,782
Percent (%)	3.8
Rate	1.3	1.2	1.3	0.3	0.3	0.3
Rate ratio	3.8	3.6	4.1

Deaths from hypertension are not common, however hypertension is a major risk factor for fatal cardiovascular diseases such as coronary (ischaemic) heart disease and cerebrovascular disease (including stroke) [14]. Due to the relatively low number of direct deaths from this disease, recent national Indigenous death data is not readily available, however figures for NSW recorded ten Indigenous deaths from hypertension in 2009, or 1.7% of all Indigenous deaths [4]. Figures for the non-Indigenous population show a similar proportion of deaths, at 1.6% of all non-Indigenous deaths. Deaths from hypertension were higher for Indigenous females with a proportion of 2.9%, and 0.3% for Indigenous males, of all Indigenous deaths.

For the period 2002-2006, hypertension among Indigenous Australians, accounted for 94 deaths or 4.7% of all Indigenous cardiovascular deaths (Table 15) [7].

Table 15: Deaths of Indigenous Australians for hypertension, by sex, Qld, WA, SA and NT, 2002-2006

Sex	Hypertension
Source: Australian Institute of Health and Welfare, 2008 [7]
Notes: Rates are per 100,000. Rates are directly age-standardised using the 2001 Australian standard population Rate ratio is the Indigenous rate divided by the non-Indigenous rate. All ratios are significant at the p<0.05 level.
Males
Number	36
Percent (%)	3.2
Rate	17.5
Rate ratio	3.4
Females
Number	58
Percent (%)	6.6
Rate	26.8
Rate ratio	4.3
Persons
Number	94
Percent (%)	4.7
Rate	23.1
Rate ratio	3.9

Indigenous female deaths from hypertension were reported to be 58 deaths or 6.6%, these figures were higher than among Indigenous males recording 36 deaths or 3.2% (Table 15) [7]. Deaths from hypertension were more common among Indigenous Australians than non-Indigenous Australians with a rate of almost four times. Indigenous female were 4.3 times more likely to die from hypertension than non-Indigenous females, and Indigenous males were 3.4 times more likely to die from this disease than their non-Indigenous counterparts.

Rheumatic heart disease

Rheumatic heart disease refers to the long term damage of the heart valves and heart muscle caused by acute rheumatic fever [14]. Acute rheumatic fever is an inflammatory disease and can cause damage to the heart valves, muscle and lining, as well as connective tissues in the brain and other parts of the body such as joints. An untreated bacterial throat infection, specifically Group A streptococcus, is thought to be a common cause of acute rheumatic fever, and there is growing evidence that attributes streptococcal skin sores as a further cause of this disease.

Rheumatic heart disease (including acute rheumatic fever) is linked to poor living conditions including low levels of hygiene, lack of clean water, inadequate sewerage facilities, overcrowding and limited access to health care [14]. As such, the morbidity and mortality associated with rheumatic heart disease (including rheumatic fever) can be largely prevented.

Of all cardiovascular heart disease, rheumatic heart disease and acute rheumatic fever has the greatest disparity in prevalence between the Indigenous Australian population and the non-Indigenous Australian population. Indigenous children and young adults are the most affected by this disease.

Data on this disease is derived from the registers of rheumatic heart disease and acute rheumatic fever in the Top End of the NT and Central Australia. There are a number of limitations in the data including area coverage and comparison data due to difficulties with determining denominator populations⁹ [7]. Reflecting the continuing importance of acute rheumatic fever and rheumatic heart disease, particularly in the NT, registers were established in these areas in 1997 (NT) and 2002 (Central Australia) to collect data on new and existing cases [14]. The registers maintain records of people with known past rheumatic heart disease and acute rheumatic fever, and collect information about new cases. This information is essential for an effective secondary prevention program involving antibiotic prophylaxis. The information presented in this section has been compiled by the Australian Institute of Health and Welfare from data extracted from the registers.

In 2003-2006, in the NT and Central Australia, there were 251 notifications of new and recurrent cases of acute rheumatic fever (Table 16) [7]. Of these cases, 247 or 98.4% were Indigenous Australians. There were more cases recorded in the NT, 150 cases, than in Central Australia, 97 cases [7]. Almost all cases were Indigenous Australian, 97% in the NT and 100% in Central Australia. Recurrent cases made up 27% of cases for the NT and 30% for Central Australia [14].

In 2003-2006, more than half (53.8%) of the Indigenous Australian notifications were for people aged 5-14 years, with a rate of 2.9 cases per 1,000 population. The rates for acute rheumatic fever were highest for Indigenous females in the 5-14 years age group, at a level of 2.9 cases per 1,000 (Table 16) [7]. There were more Indigenous female notifications in total for acute rheumatic fever (145 notifications, 59%) than Indigenous males (102 notifications, 41%).

Table 16: Prevalence of acute rheumatic fever, Indigenous Australians by sex, selected age groups, Top End NT and Central Australia, 2003 -2006

Sex	Age groups
	5-14	15-24	25-34	Total
Source: Australian Institute of Health and Welfare, 2008 [7]
Notes: Rates are per 1,000 Age-specific rates calculated using the average number of registrations for 2003-2006 divided by the 2001 estimated resident Indigenous Australian population for the Top End, NT and Central Australia. Total includes missing figures
Males
Number	58	28	8	102
Percent (%)	56.9	27.5	7.8	100.0
Rate	2.0	1.2	0.4	0.9
Females
Number	75	36	14	145
Percent (%)	51.7	24.8	9.7	100.0
Rate	2.9	1.6	0.7	1.3
Persons
Number	133	64	22	247
Percent (%)	53.8	25.9	8.9	100.0
Rate	2.5	1.4	0.6	1.1

It has been established that Indigenous Australians experience far greater levels of rheumatic heart disease than non-Indigenous Australians. In 2002-2006, rates of rheumatic heart disease among Indigenous Australians were between 29.6 times greater in Central Australia and 34.7 times greater in the Top End of the NT, than their non-Indigenous counterparts [14]. In the Top End of NT and Central Australia, in 2006, there were 1,402 rheumatic heart disease cases recorded, there were nearly three times as many cases recorded in the NT, 1,053, than in Central Australia, 349, [14] [7]. Almost all cases were Indigenous Australian, 91% in the NT and 94% in Central Australia. In 2006, the rates for rheumatic heart disease were highest for Indigenous females, 30.1 in the NT, and the greatest disparity was for Indigenous females in Central Australia with a rate ratio of 23.1 (Table 17) [7].

Table 17: Prevalence of rheumatic heart disease, Indigenous Australians by sex, selected areas, Top End NT and Central Australia, 2006

Area	Indigenous status
	Indigenous rate	Non-Indigenous rate	Rate ratio
Source: Australian Institute of Health and Welfare, 2008 [7]
Notes: Rates are per 1,000 Rates are directly age-standardised using the 2001 Australian standard population. Rate ratio is the Indigenous rate divided by the non-Indigenous rate. All ratios are significant at the p<0.05 level
Top End, NT
Males	15.4	0.7	21.7
Females	30.1	1.6	18.8
Persons	22.8	1.1	20.9
Central Australia
Males	15.2	1.4	11.2
Females	25.9	1.1	23.1
Persons	20.6	1.1	18.0

In 2006, Indigenous females experienced a greater rate of this disease than Indigenous males with age-standardised rates of 29.0 and 15.6 respectively (Table 18) [7]. Indigenous females also experienced greater disparity with their non-Indigenous counterparts than Indigenous males with age-standardised rate ratios of 19.3 and 18.8 respectively.

Rheumatic heart disease registrations were most common among the Indigenous Australian 15-24 years age group with age-specific rates of 31.3, and the greatest disparity was also among this age group with an age-specific rate ratio of 61.1 times greater (Table 18) [7]. The greatest disparity for Indigenous males was among the 25-34 years age group with an age-specific rate ratio of 88.3 and for Indigenous females, the 0-14 years age group with a 148.7 age-specific rate ratio.

Table 18: Prevalence of rheumatic heart disease, Indigenous Australians by sex and selected age groups, Top End NT and Central Australia, 2006

Sex	Age groups
	0-14	15-24	25-34	35-44	45-54	55-64	65+	Total	Total ASR
Australian Institute of Health and Welfare, 2008 [7]
Notes: Rates are per 1,000 Age-specific rates calculated using the 2001 estimated resident Indigenous Australian population for the Top End, NT and Central Australia. Rate ratio is the Indigenous rate divided by the non-Indigenous rate. All ratios are significant at the p<0.05 level Total ASR uses age-standardised rates
Male
Number	132	119	94	44	33	18	8	448	448
Percent (%)	29.5	26.6	21.0	9.8	7.4	4.0	1.8	100.0	100.0
Rate	12.5	20.6	19.0	13.0	16.0	17.0	12.0	15.7	15.6
Rate ratio	28.3	42.7	88.3	29.3	37.1	13.6	4.8	28.1	18.8
Female
Number	194	238	184	92	80	38	14	840	840
Percent (%)	23.1	28.3	21.9	11.0	9.5	4.5	1.7	100.0	100.0
Rate	19.9	42.3	36.9	25.2	35.9	31.8	14.8	29.6	29.0
Rate ratio	148.7	77.4	37.2	27.5	27.1	8.6	3.2	27.1	19.3
Total
Number	326	357	278	136	113	56	22	1288	1288
Percent (%)	25.3	27.7	21.6	10.6	8.8	4.3	1.7	100.0	100.0
Rate	16.0	31.3	28.0	19.3	26.3	24.9	13.6	22.6	22.3
Rate ratio	54.9	61.1	47.3	29.1	31.3	11.1	3.9	28.0	25.5

There were 686 admissions of Indigenous Australians to hospital for rheumatic heart disease (including acute rheumatic fever) in the two-year period 2004-06 (Table 3) (Table 19) [7]. Admission rates for Indigenous Australians for rheumatic heart disease (including acute rheumatic fever) were 7.0 times higher than non-Indigenous Australians.

Table 19: Hospitalisations of Indigenous Australians for rheumatic heart disease (including acute rheumatic fever), by sex, Australia, 2004-06

Sex	Rheumatic heart disease (including acute rheumatic fever)
Source: Australian Institute of Health and Welfare, 2008 [7]
Notes: Rates are per 1,000 Rates are directly age-standardised using the 2001 Australian standard population. Rate ratio is the Indigenous rate divided by the non-Indigenous rate. All ratios are significant at the p<0.05 level.
Male
Number	241
Percent (%)	3.0
Rate	0.4
Rate ratio	4.8
Female
Number	445
Percent (%)	6.1
Rate	0.9
Rate ratio	8.6
Total
Number	686
Percent (%)	4.5
Rate	0.7
Rate ratio	7.0

The actual numbers of deaths for rheumatic heart disease are relatively low however this disease continues to affect Indigenous Australians at a substantially higher rate than non-Indigenous Australians. In 2002-2005, Indigenous Australians were between 15 and 25 times more likely to die from this disease than non-Indigenous Australians, after adjusting for the difference in age structures of the two population groups (Table 5) [14]. As this disease can be largely prevented, it is thought that these deaths could be avoided.

In 2009, in the NT, there were 7 deaths (1.6%) recorded for rheumatic heart disease for Indigenous Australians, approximately 1.6% of male and 1.5% of female Indigenous deaths [4].

For the period 2002-2006, rheumatic heart disease accounted for 97 deaths or 4.8% of all Indigenous cardiovascular deaths [7] (Table 20).

Table 20: Deaths of Indigenous Australians for rheumatic heart disease, by sex, Qld, WA, SA and NT, 2002-2006

Sex	Rheumatic heart disease
Source: Australian Institute of Health and Welfare, 2008 [7]
Notes: Rates are per 1,000 Rates are directly age-standardised using the 2001 Australian standard population. Rate ratio is the Indigenous rate divided by the non-Indigenous rate. All ratios are significant at the p<0.05 level.
Male
Number	30
Percent (%)	2.7
Rate	6.2
Rate ratio	6.1
Female
Number	67
Percent (%)	7.6
Rate	16.0
Rate ratio	10.9
Total
Number	97
Percent (%)	4.8
Rate	11.5
Rate ratio	9.0

In 2002-2006, Indigenous female deaths from rheumatic heart disease were reported to be 67 deaths or 7.6%, these figures were higher than among Indigenous males recording 30 deaths or 2.7% (Table 20) [7]. Nearly half of Indigenous deaths from rheumatic heart disease occurred in the 35-54 years age group, 45% for Indigenous females and 43% for Indigenous males [14]. Deaths from rheumatic heart disease were more common among Indigenous Australians than non-Indigenous Australians with a rate of almost nine times. Indigenous female were 10.9 times more likely to die from rheumatic heart disease than non-Indigenous females, and Indigenous males were 6.1 times more likely to die from this disease than their non-Indigenous counterparts (Table 20) [7].

Congenital heart disease

Congenital heart disease refers to conditions or malfunctions of the heart at birth, and usually results in ongoing morbidity or death [19]. Congenital heart disease includes the main conditions: transposition of the great vessels; tetralogy of Fallot; hypoplastic left heart syndrome; and coarctation¹⁰.

More recent data are restricted to major types of congenital heart disease included in the general reports of congenital anomalies in Australia. For cases reported in Australia in 2002-2003, transposition of the great vessels, tetralogy of Fallot, and coarctation of the aorta were more common among Indigenous people than non-Indigenous people, and hypoplastic left heart syndrome less common (Table 21) [19]. Differences in prevalence between Indigenous and non-Indigenous cases were not found to be statistically significant.

Table 21: Numbers and prevalence for selected types of congenital heart disease, by Indigenous status, and Indigenous:non-Indigenous prevalence ratio, Australia, 2002-2003

Type of congenital heart disease	Indigenous		Non-Indigenous		Ratio
	Number	Prevalence	Number	Prevalence
Source: Abeywardana, Sullivan, 2008 [19]
Notes: The source document was restricted to these four types of congenital heart disease. Figures do not include cases for the NT Prevalence is number of cases per 10,000 women who gave birth. Ratio is the Indigenous prevalence divided by the non-Indigenous prevalence None of the differences in prevalence between Indigenous and non-Indigenous cases is statistically significant
Transposition of the great vessels	11	7.4	194	4.1	1.8
Tetralogy of Fallot	9	6.1	145	3.1	2.0
Hypoplastic left heart syndrome	2	1.3	79	1.7	0.8
Coarctation of aorta	7	4.7	1.7	3.6	1.3

The data on the overall extent of congenital heart disease among Indigenous babies is limited. One of the most comprehensive reports was based on notifications received by the Western Australian Birth Defects Registry regarding babies born in WA in the 10 year period 1980-1989 [20]. Congenital heart disease was found to be 30% more common among Indigenous babies than non-Indigenous babies, affecting almost 10 out of 1,000 Indigenous babies. The overall level for WA was similar to the levels documented for other parts of the world. Congenital heart defects occurring with other defects were significantly more frequent in Indigenous babies than non-Indigenous babies, but the excess of isolated heart defects was of borderline significance. Ventricular septal defect was responsible for more than two-fifths (43%) of cases of isolated congenital heart disease.

A report on congenital heart disease among babies born in Central Australia during the period 1993-2000 based on patient records of the Alice Springs Hospital, Central Australia, found that the overall rate of congenital heart disease was 17.5 [21]. The overall incidence of congenital heart disease was found to be similar for Indigenous babies and non-Indigenous babies. Among Indigenous babies the rate was found to be 19.0 and for non-Indigenous babies, 16.1 per 1,000 live births (Table 22) [21].

Table 22: Numbers and incidence of congenital heart disease, by Indigenous status and disease type, and Indigenous:non-Indigenous incidence ratio, central Australia, 1993-2000

Type of congenital heart disease	Indigenous		Non-Indigenous		Ratio
	Number	Incidence	Number	Incidence
Source: Bolisetty, et al., 2004 [21]
Notes: Based on cases confirmed by echocardiography in the Alice Springs Hospital among babies born between 1 January 1993 and 30 June 2000 . Incidence is number of cases per 1,000 live births Ratio is the Indigenous incidence divided by the non-Indigenous incidence. None of the differences in incidence between Indigenous and non-Indigenous cases is statistically significant
Patent ductus arteriosus	30	10.0	32	10.1	1.0
Atrial septal defect	5	1.7	7	2.2	0.8
Patent ductus arteriosus	5	1.7	3	0.9	1.8
Double outlet right ventricle	4	1.3	1	0.3	4.2
Other defects	13	4.3	8	2.5	1.7
All defects	57	19.0	51	16.1	1.2

The incidence of congenital heart disease among Indigenous babies was calculated to be 18% higher than non-Indigenous babies, however this was not statistically significant [21]. Cases, which were confirmed by electrocardiography, excluded patent ductus arteriosus in babies born before 37 weeks gestation, asymptomatic patent ductus arteriosus in the first 3 months of life, and a number of other minor defects with no clinical significance.

Impact of cardiovascular health

Costs

The costs of cardiovascular health in Australia refer to various elements of the disease burden. Financial costs and health expenditure can be calculated, including various treatment aspects and hospitalisation [22]. Further costs include the associated morbidity of this disease for the individual, their family and community. While avoidable and preventable deaths are an additional cost related factor to be considered when calculating the burden of this disease [7].

In 2004-05, health care expenditure for cardiovascular disease of $5.9 billion accounted for 11% of the total allocated health system expenditure [22]. This was the most expensive group of diseases in Australia in terms of direct health care expenditure. These figures equate to $284 per person in the population, or $1,482 per affected person. It is probable that these amounts are underestimates because a significant amount of pharmaceutical use relevant to cardiovascular disease was allocated elsewhere. Coronary (ischaemic) heart disease accounted for $1,813 or 30.5% of the total expenditure for cardiovascular disease, and stroke accounted for $546 billion or 9.2 % [22]. For all cardiovascular disease, the expenditure was greatest for hospital admitted patients (50.6%) and the lowest for research (2.7%).

In 2006-07, health expenditure for the Indigenous population was estimated to be $2.9 billion, 3.3% of the total health expenditure in Australia, of $89.4 billion [23] [24]. Figures for the Indigenous Australian population specific to cardiovascular disease were not readily available for this period, and instead focused on health care expenditure by type of service and area [23] [25]. Data for 2006-07 is available for the expenditure on hospitalisation separations for cardiovascular disease and indicates that Indigenous Australians receive $86.8 million compared with $3256.4 million for non-Indigenous Australians, the Indigenous share is calculated to be 2.6% [26]. Between 2004-05 and 2006-07 the proportion of health expenditure for the Indigenous population rose from 2.8% to 3.3%¹¹ [23].

Avoidable and preventable mortality are deaths from health conditions that could have been evaded if appropriate health care was provided in a timely manner [7]. During 2002-2006, there were 4,769 Indigenous Australian deaths that could have been avoided, 7.5% of the total avoidable Australian deaths, and 73% of all Indigenous Australian deaths. For Indigenous Australians, there were 956 deaths for coronary (ischaemic) heart disease that could have been avoided, accounting for 20% of the total avoidable Indigenous Australian deaths, and at a rate 4.6 times higher than among the non-Indigenous population (Table 23) [7]. Cerebrovascular disease (including stroke) accounted for 215 avoidable Indigenous Australian deaths, 4.5% of all avoidable Indigenous deaths, at a rate 3.7 times that of non-Indigenous Australians. Rheumatic heart disease¹² was responsible for 93 avoidable Indigenous Australian deaths, 2% of all avoidable Indigenous Australian deaths, with a rate 22.7 times higher than non-Indigenous Australians.

Table 23: Numbers and rates of avoidable deaths from selected cardiovascular diseases, by Indigenous status, and Indigenous:non-Indigenous rate ratios, people aged 0-74 years, Qld, WA, SA and the NT, 2002-2006

Cause of death	Indigenous		Non-Indigenous	Rate ratio
	Number	Rate	Rate
Source: Australian Institute of Health and Welfare, 2008 [7]
Notes: Categories are based on the ICD-10-AM. ICD codes are in parentheses. Rates are per 1,000 Rates are directly age-standardised rates using the 2001 Australian standard population. Rate ratio is the Indigenous rate divided by the non-Indigenous rate. All ratios are significant at the p<0.05 level
Coronary (ischaemic) heart disease	956	149.7	32.7	4.6
Cerebrovascular disease (including stroke)	215	36.5	9.8	3.7
Rheumatic heart disease (including other valvular)	93	10.7	0.5	22.7

Risk factors

Risk factors contributing to cardiovascular disease among Indigenous Australians are complex. They reflect a combination of broad historical, social, cultural, and economic factors as well as the more commonly described proximal risk factors. The main risk factors addressed in this review include behavioural and biomedical risk factors, and while the review provides brief coverage of the historical, psychosocial and socioeconomic aspects, it has been beyond the scope of this review to address these factors in any great detail. Comorbidity of other diseases, such as diabetes and chronic kidney disease, are recognised as important contributing risk factors, which are also beyond the scope of this review¹³.

Behavioural and biomedical risk factors

Conventional risk factors for cardiovascular disease can be divided into two main categories: behavioural and biomedical [14]. Behavioural risk factors are based on an individual's behavior, such as tobacco smoking, but can be influenced by other underlying socioeconomic, psychosocial and cultural factors. Biomedical risk factors, such as high blood cholesterol, can be influenced by modifications to behaviour, lifestyle, or the use of medical interventions. Behavioural risk factors include tobacco smoking, physical inactivity, poor nutrition and risky alcohol consumption [5] [14] [27]. Biomedical risk factors include high blood pressure (hypertension) ¹⁴, high blood cholesterol, conditions of being overweight or obese, diabetes and chronic kidney disease¹⁵.

In 2004-05, in non-remote areas, at least one risk factor was present for almost all Indigenous Australians with cardiovascular disease [2]. Indigenous males were more likely to have had higher numbers of multiple risk factors than Indigenous females, and Indigenous Australians overall were more likely to have had a higher number of multiple risk factors than non-Indigenous Australians. For all the risk factors, the prevalence for Indigenous Australians was greater than that for non-Indigenous Australians, particularly diabetes, at a rate four times higher, and smoking, at a rate 2.1 times higher [14].

Smoking

Smoking is the greatest risk factor for cardiovascular disease and a broad range of other health conditions. Tobacco smoke damages both the heart and blood vessels [14]. The nicotine in tobacco smoke contributes to the development of atherosclerosis, the accrual of fat, such as cholesterol, on the walls of blood vessels. This narrows the blood vessels, reducing oxygen levels, increasing blood pressure and placing increased stress on the heart muscle. Tar and carbon monoxide, among other additives in cigarettes, can cause increased heart rate, irregular heartbeats, increased blood pressure, and can increase the risk of blood clots forming.

In 2004-05, 51% of Indigenous Australians aged 18 years and over self-reported being current smokers in the NATSIHS, compared with 24% of non-Indigenous people [2]. For both population groups, all current smokers reported smoking daily, except for 2%. Similar proportions of Indigenous males and Indigenous females reported smoking and these proportions were high across all age groups. 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%). Time analysis indicates that these levels are similar to those reported from earlier comparable surveys.

The 2007 National drug strategy household survey recorded a lower proportion of current smokers, 34% of Indigenous Australians aged 14 years or older [28]. Due to the relatively small sample size (23,356) and survey methodology, the proportion of Indigenous smokers is likely to have been underestimated.

For people with cardiovascular disease, Indigenous Australians were more than twice as likely to be daily smokers as non-Indigenous Australians. Across all age groups, Indigenous Australians with cardiovascular disease had a higher prevalence of daily smoking than non-Indigenous Australians with cardiovascular disease; this was particularly high for the 65+ age groups with rates nearly four times as high.

Physical inactivity

Physical inactivity is an important risk factor for the development of cardiovascular disease, particularly coronary (ischaemic) heart disease, heart failure and stroke [14]. Physical activity causes the body to increase strength, develop lean muscle mass, burn calories and reduce body fat and blood pressure.

Benefits of regular physical activity are not only linked to a reduction in developing cardiovascular disease, but also in reducing some of the associated risk factors (such as overweight and obesity, hypertension, type 2 diabetes, and high levels of high-density lipoprotein and total blood cholesterol).

For the period 2004-05, almost half (49%) of Indigenous Australians in non-remote areas did not participate in any physical activity during the two weeks prior to the survey [2]. Indigenous females and older Indigenous Australians were more likely to be physically inactive than Indigenous males.

Indigenous Australians had a rate of physical inactivity one and a half times that of non-Indigenous Australians [14]. The greatest disparity was seen in the 45-64 years age group, with a rate 1.6 times higher for Indigenous males, and 1.7 times higher for Indigenous females, than their non-Indigenous counterparts.

Of Indigenous Australians living in non-remote areas who reported having cardiovascular disease, 58% were physically inactive [2]. After adjusting for age, Indigenous males and Indigenous females had similar levels of inactivity. Physical inactivity levels increased with age, and almost three-quarters of Indigenous Australians aged 65 years+, who had cardiovascular disease, were sedentary.

For people with cardiovascular disease, Indigenous Australians were 1.6 times as likely to be physically inactive than non-Indigenous Australians [14]. Across all age groups, Indigenous Australians with cardiovascular disease had a higher prevalence of physical inactivity than non-Indigenous Australians with cardiovascular disease; this was particularly high for the 45-64 years age groups with rates almost twice as high.

Nutrition

Poor nutrition, including the inadequate consumption of fruit and vegetables, can increase the risk of developing chronic diseases, particularly cardiovascular disease, including: coronary (ischaemic) heart disease; stroke; hypertension; and atherosclerosis [14]. A diet high in saturated fat and salt, commonly found in processed foods, has been linked to high blood pressure, high blood cholesterol levels, type 2 diabetes, and conditions of being overweight or obese. Excess fat and salts in the circulatory system can place increased pressure on the heart muscle and blood vessels through the accrual of fatty substances. These substances can reduce the efficiency of blood and oxygen flow placing stress on the system, blockages can eventually occur and the results can be fatal.

Dietary guidelines have been developed, and make recommendations on the intake of certain food groups [29]. Regular consumption of fruit and vegetables can lower blood cholesterol and blood pressure and help to reduce the risk of developing atherosclerosis, coronary (ischaemic) heart disease and stroke.

For the period 2004-05 approximately 15% of Indigenous Australians did not eat fruit on a daily basis; 6% did not eat enough vegetables daily; and 3% did not eat enough fruit or vegetables daily [2]. Poor nutrition rates were higher among Indigenous males, who were, after adjusting for age, 1.4 times more likely than Indigenous females to not eat any fruit or vegetables daily.

Indigenous Australians had a rate of poor nutrition at a level twice that of non-Indigenous Australians, for the inadequate consumption of fruit [14]. The greatest disparity was seen for inadequate consumption of vegetables, with a rate 6.2 times higher and 9.5 times higher for inadequate consumption of fruit and vegetables, than their non-Indigenous counterparts. For people with cardiovascular disease, Indigenous Australians were 1.3 times more likely to have poor nutrition levels than non-Indigenous Australians [14].

Alcohol consumption

Alcohol consumption can increase blood pressure and blood triglyceride levels, this can place strain on the circulatory system, and as a result it can increase the risk of heart failure, stroke and abnormal heart rhythm [14]. Alcohol consumption can also contribute towards conditions of being overweight or obese, and increase the risk of developing type 2 diabetes.

Alcohol guidelines have been developed, and make recommendations on the intake of alcohol for different population groups including: adult male and adult females; children; and pregnant women [30]. The guidelines now refer to a progressive increase in the risk of harm with the amount of alcohol consumed rather than specifying the risks for different levels of alcohol consumption¹⁶.

For the period 2004-2005, almost half of Indigenous Australians, aged 18 years and over, consumed alcohol in the week prior to the NATSIHS [2]. Over one-third (32%) consumed alcohol at low risk levels, 16% at risky levels, and 8% at high risk levels.

Alcohol consumption for Indigenous males was higher than Indigenous females, 1.4 times for risky levels, and 2 times the rate for high risk levels [14]. Indigenous males had the highest level of risky alcohol consumption among the 35-44 years age group (24%) and among Indigenous females the 25-34 years age group (16%).

Indigenous Australians had a rate of risky/high risk alcohol consumption 1.2 times that of non-Indigenous Australians [14]. The rate for high risk alcohol consumption for Indigenous Australians was slightly higher at 1.5 times that of non-Indigenous Australians.

For people with cardiovascular disease, Indigenous Australians were 1.6 times more likely to have consumed alcohol at a high risk level than non-Indigenous Australians [14]. Indigenous males with cardiovascular disease had a higher prevalence of high risk alcohol consumption than non-Indigenous males with cardiovascular disease, with rates almost twice as high (1.9). Indigenous females had a prevalence of high risk alcohol consumption similar to non-Indigenous females with a rate of 1.2. Indigenous Australians with cardiovascular disease had higher abstention rates than their non-Indigenous counterparts, 2.2 times higher for Indigenous males and 1.7 times higher for Indigenous females.

Overweight and obesity

Conditions of being overweight or obese are caused by excess body fat. This results when the energy intake from the diet is greater than that being used up by the body through physical activity [14]. Indigenous Australians are at greater risk of developing cardiovascular disease, particularly coronary (ischaemic) heart disease, stroke and type 2 diabetes, if they are overweight or obese [31]. Other risk factors for cardiovascular disease are also exacerbated by excess body fat, and include: high blood pressure; high blood cholesterol; and high levels of blood triglycerides.

The classification measure used for bodyweight and excess body fat is the Body mass index (BMI). It classifies BMI ranges into categories including: underweight, healthy weight; overweight; obese; and morbidly obese¹⁷ [14]. This measure may not be suitable for all population groups. There is increasing evidence to suggest that waist measurement or waist-to-hip ratio are more accurate in predicting the risk of cardiovascular disease, however, measures of BMI are routinely reported in many national and other surveys [14] [32].

In the period 2004-05, 60% of Indigenous Australians were reported to be overweight, and 31% were obese (13% of whom were morbidly obese) [2]. Indigenous males were more likely to be overweight than Indigenous females (1.1 times), however Indigenous females were more likely to be obese (1.2 times). Obesity levels were highest among Indigenous Australians in the 45-64 years age group (39%) and the 65+ years age group (33%) [14].

Indigenous Australians were more likely to be overweight (rate ratio: 1.2); obese (1.9); and morbidly obese (3+), than their non-Indigenous counterparts [14]. Across all age groups, Indigenous Australians had a higher prevalence of obesity. The greatest disparity was seen in the 18-24 years age group, with a rate 2.4 times higher, and in the 65+ years age group, with a rate of 2.1 times higher than their non-Indigenous counterparts.

For people with cardiovascular disease, Indigenous Australians had a higher prevalence in all of the excess weight categories than non-Indigenous Australians [14]. Indigenous Australians with cardiovascular disease were 1.2 times more likely to be overweight than non-Indigenous Australians, 1.6 times more likely to be obese, and 2.4 more likely to be morbidly obese.

Social and emotional wellbeing

Research has highlighted the important relationships between cardiovascular disease and social and emotional wellbeing [14]. Factors such as social isolation, stress, depression, and lack of social support in particular have now been acknowledged as factors independently associated with the cause and prognosis of coronary (ischaemic) heart disease [14] [17] [33]. Risk factors of a social and emotional wellbeing nature are now recognised with similar importance to conventional risk factors such as smoking, high blood cholesterol and high blood pressure.

Indigenous Australians are recognised as a population whose social disadvantage is strongly associated with both psychosocial and conventional risk factors [33] [34]. The acknowledgment of the equal importance of these psychosocial factors and conventional risk factors has clear implications for the assessment and management of coronary (ischaemic) heart disease among Indigenous Australians, and for public health policy and research.

Other risk factors that fall under the umbrella of social and emotional wellbeing, have been recognised as important contributors to the development of cardiovascular disease among Indigenous Australians, these have been termed 'upstream' factors and include:

• cultural and historical factors, such as loss of land, and disruptions to culture, language and identity [14] [35];
• environmental and socioeconomic factors, such as poor housing, low education and income [14];
• psychosocial stressors, such as death of a family member or close friend, serious injury or disability [14]; and
• limited access to appropriate health care, both preventive and clinical [36] [37].

Understanding the actual contributions of upstream factors is important when addressing modifiable risk factors. Many of these upstream factors contribute to behavioural risk factors. Low socio-economic status, for example, contributes to behavioural risk factors such as smoking, physical inactivity and poor nutrition (which can result in conditions of being overweight or obese) [14]. The extent to which various upstream factors contribute to biomedical risk factors (such as high blood cholesterol and high blood pressure) is unclear.

Comorbidity

Indigenous Australians with cardiovascular disease also have other health problems and multiple behavioural and biomedical risk factors [17] [38] [39]. Having more than one risk factor magnifies the risk of cardiovascular disease by multiplying that risk rather than just having an additive effect [14] [39]. Thorough analysis and an understanding of the roles of all these factors would be important in the development and implementation of policies and strategies addressing cardiovascular disease among Indigenous Australians¹⁸.

Policies and strategies

National Indigenous Australian health information for chronic disease can be acquired from the Australian Government: mainstream areas of the Department of Health and Ageing (DoHA); and the Office for Aboriginal and Torres Strait Islander Health (OATSIH). From here, further information including policies, strategies, guidelines, programs, funding commitments and future outcomes, is available from several sources. Selected information on some of the key developments in the area of Indigenous Australian cardiovascular health are included below; it is not inclusive of all developments in the area.

National chronic disease strategy

Cardiovascular disease forms part of the Australian Government's National chronic disease strategy endorsed at the Australian Health Ministers' Conference in 2005 [40]. The strategy has three main components: an overarching framework for improving chronic disease prevention and management in Australia; National service improvement frameworks for five chronic diseases, including heart, stroke and vascular disease [41]; and the Blueprint, a framework for nationwide surveillance for chronic diseases and associated determinants [42].

The National service improvement framework for heart, stroke and vascular disease is not specific for Indigenous Australians, but states that all health services provided to Indigenous Australians should be provided in accordance with the Australian Health Ministers' Advisory Council's Cultural respect framework for Aboriginal and Torres Strait Islander health, 2004-2009 [41] [43]. The framework identifies the barriers to health care access for Indigenous Australians including: distance and access to transport; affordability; availability of health professionals; cultural appropriateness; and acceptability of services.

The rheumatic fever strategy

This strategy aims to address rheumatic heart disease (including acute rheumatic fever) among Indigenous Australians, particularly children. It provides a coordinated program including prevention and treatment; funding for state based register and control programs in the NT, WA and Qld; and a national coordination unit, Rheumatic Heart Disease Australia. The keys outcomes of this strategy include improvements to clinical responses, and support for monitoring and treatment of this disease, through the establishment of a national data collection system.

The Rheumatic heart disease program encompasses both the Top End and Central Australian programs, and is coordinated by the Centre for Disease Control Unit, Northern Territory Government, Department of Health and Families. The program was established in the Top End of the NT in 1997, and aimed to address the high rates of rheumatic heart disease (including acute rheumatic fever) among Indigenous Australians in central and northern Australia [44] [45]. It was extended to include central Australia in 2000 and became fully operational in 2002.

Specific aims of the program include: conducting surveillance, identifying and registering new and recurrent cases; providing education and training for health care providers; improving clinical care and follow-up; providing education and health promotion to clients, families and the community; and supporting the uptake of and adherence to secondary prophylaxis [44] [46] [47].

Guidelines for the diagnosis and management of rheumatic heart disease (including acute rheumatic fever) in Australia are based on a review by the National Heart Foundation of Australia and the Cardiac Society of Australia and New Zealand, and informed by the National Health and Medical Research Council [46].

Cardiac rehabilitation geographic information system

Resources to assist health professionals working with Indigenous Australians, who have experienced a cardiac event, were developed by the National Health and Medical Research Council. These resources were developed by a committee, with consultation from National Aboriginal Community Controlled Health Organisation and the Australian Indigenous Doctors' Association [48] [49].

The committee consulted widely with health professionals and consumers to determine why Indigenous Australians do not attend cardiac rehabilitation programs, and how services can be made more accessible. The information contributed to a practical guide for health professionals Strengthening cardiac rehabilitation and secondary prevention for Aboriginal and Torres Strait Islander peoples: a guide for health professionals [48] [49].

In addition, the committee commissioned the Cardiac geographic information system project. This involved the development of an interactive report and maps that integrate the location of cardiac rehabilitation services with patients who have had a cardiac event. Designed as a resource for primary health care providers and cardiac rehabilitation services, the tool can be used to locate services and understand the distribution of cardiac illness in local areas [47].

Outreach programs

The barriers faced by many remote Indigenous Australians accessing specialist hospital care are substantial. Outreach delivery of specialist services has overcome some of the barriers relating to distance, communication and cultural appropriateness [50].

The Medical specialist outreach assistance program was funded by the Department of Health and Ageing to improve access to medical specialist services for people living in rural and remote Australia [51] [52]. The outreach specialist services provided by the NT and state governments allowed for financial assistance to cover some of the costs for specialists associated with delivering outreach services, including: travel; accommodation; consulting room hire costs; as well as professional support to local general practitioners; and specialists and other health professionals, such as allied health professionals.

The delivery and support of outreach medical specialist services achieved considerable success since 2004 [51] [52]. The program provided more than 1,375 specialist services annually to rural and remote communities. Additional funding of $9 million over three years, commenced in 2008-09, to support the expansion of the program to improve rural and remote community access to a range of medical specialist services. The aim was to provide opportunities for new and expanded services, and to reduce waiting lists for people in rural and remote communities to obtain treatment.

Indigenous chronic disease fund

Indigenous health, Outcome 8 of the 2011-12 Australian Government budget, included the program objective, to improve the prevention and management of chronic disease through the Aboriginal and Torres Strait Islander chronic disease fund [53]. This fund was developed after a review of administration arrangements in the portfolio, and will be established by consolidating exiting programs and initiatives of the Indigenous chronic disease package [54].

Part of this objective includes three key areas: preventing chronic disease; improving the detection and ongoing management of chronic disease; and, building the capacity of the workforce [53]. Prevention areas include the establishment of increased regionally focused teams to deliver preventative health care that focuses on reducing risk factors for chronic disease. Areas of detection and management will see improvements to the range of services: greater services to those at risk of developing chronic disease; the reduction of prescription payments to those at risk; greater geographic coverage of management services; and, further training to health workers in chronic disease self management support for patients. The workforce area includes: funding for orientation and training in the Indigenous health workforce; support and encouragement to join or remain in the workforce; an advertising campaign and an engagement program to attract students and health professionals to the field; and funding for additional staff of nine health professionals; 11 practice managers; and 22 Indigenous outreach workers, nationally.

Prevention and rehabilitation

Much of the morbidity and mortality caused by cardiovascular disease is preventable, both in terms of initial onset of the disease (primary prevention) and in terms of managing and controlling established disease (secondary prevention and rehabilitation) [5] [7] [14]. Cardiovascular disease has attracted substantial attention due to the largely preventable aspects of the disease, and the associated high level of health burden and costs in Australia. This attention has contributed to advances in cardiovascular health in mainstream Australia; however these advances have not been translated into the Indigenous population. This is evidenced through the continuing high prevalence, hospitalisation and death rates of Indigenous Australians from this disease, than other Australians [24] [4] [15].

For the period 2002-2003, hospital and mortality records showed that Indigenous Australians were more likely to suffer acute myocardial infarction, and were more likely to die from acute myocardial infarction with or without hospital admission [17]. During their admission, Indigenous Australians were less likely to receive key medical investigations or common procedures such as coronary bypass surgery or angioplasty. Indigenous Australians admitted to hospital for coronary (ischaemic) heart disease had more complex cases (with one or more comorbidities such as diabetes or renal disease), but this did not appear to account for differences in procedure rates. Improvements to the rates of procedures for the Indigenous population may occur if the barriers they face in terms of implementing primary and secondary prevention strategies are addressed [55].

Barriers for Indigenous Australians

Indigenous Australians are culturally diverse, with each culture providing unique access barriers to health care services [35] [49]. Health service planning should consider the needs of individual communities, and rates of disease, rather than adopting a 'one size fits all' approach. Therefore, while primary prevention strategies might vary little across communities, the level of resourcing for screening and treatment programs should depend on the disease burden [39].

Other barriers experienced by Indigenous Australians include: poor coordination across the health system; socio-economic disadvantage; poor access to both acute care services and primary health care; the availability of transport to health services; delays in presentation; and language and cultural differences [56] [35] [57] [58] [59] [60].

Primary prevention

Primary prevention of cardiovascular disease is complicated by the large and ever-increasing clinical evidence, the wide range of at-risk groups, and the plethora of recommended interventions [61]. At a population level, everyone is encouraged to reduce their cardiovascular risk by eating a healthy and varied diet, being physical active on a regular basis, and to cease smoking. For those who have one or more risk factors for cardiovascular disease, such as high blood pressure, or raised blood lipid levels, diabetes or chronic kidney disease; primary prevention strategies must be tailored to the individual. It has been observed that the majority of Indigenous Australians who present with a cardiovascular event have at least one comorbidity or risk factor [38] [62] [17], and should therefore receive individually tailored prevention programs.

The case for primary prevention of cardiovascular disease is supported by evidence that suggests that high levels of cardiovascular disease are not 'natural' and that, in principle, they can be considerably lowered [5]. Prevalence rates of cardiovascular disease vary substantially between countries, different population groups within the same country, and for the same population groups over time. Modifiable risk factors, such as a high level of blood cholesterol, tobacco smoking, high blood pressure, and physical inactivity, contribute to a large proportion of the deaths from this disease. All groups and individuals have the capacity to reduce their levels of risk factors, often markedly. Trials show that when risk factors are reduced, so are the rates of heart, stroke, and vascular disease.

A thorough discussion of the primary prevention of cardiovascular disease is beyond the scope of this review, but it is important to note that the risk factors for cardiovascular disease are often linked, meaning that they act synergistically when they occur in the same person [5]. In addition, the reduction of these risk factors will also help prevent several other major diseases that share these risk factors, such as type 2 diabetes. Thus, risk factors should not be viewed in isolation when looking at possible prevention strategies.

Rheumatic heart disease

Acute rheumatic fever is an auto-immune response to bacterial infection with group A streptococcus which often results in lasting damage to heart valves. This is known as rheumatic heart disease and it is an important cause of premature mortality [46].

Rheumatic heart disease (including rheumatic fever) is a preventable cause of morbidity and mortality among Indigenous Australians, and organised primary health care is essential for its control [46]. Genuine prevention of this disease requires improvements in socioeconomic conditions and housing, which would lower the carriage and transmission of group A streptococci, and reduce the need for early detection and treatment with antibiotics to prevent rheumatic fever [63]. There is also a great need for health care providers to concentrate on meeting the needs of Indigenous Australians with this disease through better prevention, diagnosis, service delivery and access to care [64] [65].

Primary prevention requires broad political commitment to addressing the social, economic and environmental inequities experienced by Indigenous Australians [64] [66]. Improvements in the interrelated areas of housing, education and employment are required to address chronic disease, rather than concentrating solely on health service delivery [67]. Even after allowing for the effects of behavioural and biomedical risk factors such as smoking, physical inactivity and obesity; socioeconomic variables remain independently associated with the risk of death from cardiovascular disease [46] [68]. Limitations in the delivery of holistic care seem to be due to the lack of structure between services of the commonwealth, state, and territory governments in this area [69]. Many areas affecting health, including education, employment, social services, and transport, and not greatly influenced by the health sector, therefore national health policies for Indigenous Australians may require much greater integration.

There is considerable potential for reduction in the incidence of rheumatic heart disease (including acute rheumatic fever) among Indigenous Australians, but there must be committed application of the knowledge currently available [46] [66]. As well as action addressing the various behavioural risk factors, attention also needs to be directed to the adverse social, economic, and environmental conditions of many Indigenous Australians.

Secondary prevention and rehabilitation

Secondary prevention for Indigenous Australians refers to interventions for those who have experienced a cardiovascular event (for example, a heart attack or stroke) and are therefore at risk of another event [5]. Secondary prevention includes treatment with medication, as well as rehabilitation to help patients return to an active life. Rehabilitation begins during a patient's hospital stay, but the majority occurs after discharge. Continuing medical treatment after a cardiovascular event can help to control symptoms and reduce ongoing risk factor levels. The reduction of risk factors has even greater potential to prevent further cardiovascular events in those with established cardiovascular disease than in those without.

Improvements in secondary prevention services for cardiovascular disease, including outpatient rehabilitation, is critical for reducing the likelihood of further cardiovascular events [58]. It is important for Indigenous communities and health services to be involved in the continual development of secondary prevention and rehabilitation programs for Indigenous Australians, particularly in rural and remote areas.

Cardiac rehabilitation

Cardiac rehabilitation is an important part of secondary prevention of coronary (ischaemic) heart disease, aiming to give people the confidence, motivation and skills to make a lifelong commitment to a healthy lifestyle and greater wellbeing [37].

The level of Indigenous participation in cardiac rehabilitation programs is much lower than it should be [5] [58] [59]. Appropriate services are not available or accessible for all Indigenous Australians with cardiovascular disease, especially those in rural and remote Australia. Not all patients eligible for cardiac rehabilitation are offered a place, even when a program is available and accessible. Despite increases in the awareness of such issues, routine referral is still not standard practice and some patients who are referred do not attend. Rural and remote services need to be coordinated and the shortage of allied health staff acknowledged. A standardised data-collection tool is needed, so more information on attendance at cardiac rehabilitation programs can be gathered [55]. Programs for Indigenous Australians also need to be made more accessible and culturally appropriate, so attendance rates improve [48] [49].

Stroke rehabilitation

Stroke can result in the sudden and catastrophic decline in ability, lifestyle, and independence, especially for younger patients [5]. Social and emotional wellbeing may also be affected by stoke, and conditions such as depression may develop. Family members and carers of people who have suffered a stroke may also be vulnerable to these conditions [41] [70].Various factors are associated with successful stroke rehabilitation, but there is no standardised approach for identifying who will benefit from rehabilitation. The majority of strokes in the general population affect older people, but, rates among Indigenous Australians are similar to those for non-Indigenous Australians who are around 20 years older. Stroke rehabilitation programs rarely meet the specific needs of younger patients, and this is likely to be particularly so for young Indigenous Australians [56] [70] [14].

The provision of culturally appropriate stroke rehabilitation services for Indigenous Australians is complex, particularly for patients in remote areas [56]. Some of the challenges include: difficulties in communication; misunderstandings by patients of the meaning of rehabilitation; a desire by patients of same-sex carers; poor access to care and services; difficulties with obtaining equipment and modifying the home in remote environments; and, inappropriate treatment models [56] [71] [72].

The stroke rehabilitation services available to Indigenous Australians vary greatly by location, with services clustered in some areas and few or no services in others, particularly rural and remote areas [35]. Assessment procedures, management approaches, and outcome measures vary between services, limiting effective communication between centres and impeding attempts to work towards best practice.

Despite the higher levels of mortality and morbidity from stroke in the Indigenous population, the availability of programs for primary and secondary prevention and rehabilitation for this population, especially in rural and remote areas, appear to have been fragmented [56]. Expenditure for stoke in Australia made up 9% of the total funding spent on cardiovascular disease in 2004-05, of this amount only 8% of funding went to out of hospital medical services [22], prevention services appeared relatively underfunded compared to treatment services.

Rheumatic heart disease

The secondary prevention of rheumatic heart disease (including rheumatic fever) aims to prevent recurrences of rheumatic fever using regular long-term prophylaxis with penicillin; to be effective, a high level of prophylaxis must be achieved [46]. Four-weekly courses of antibiotics are the treatment of choice, except in patients considered to be at high risk, for which 3-weekly administration is recommended. The benefits of a shorter course of medication are offset by the difficulties of achieving good adherence to the regimen. The appropriate duration of secondary prophylaxis is determined by age, time since the last episode of acute rheumatic fever, and potential harm from recurrent disease. For Indigenous Australians with established rheumatic valvular disease, access to cardiac surgery may be important.

Future directions

Comprehensive primary health care programs and increased training and support for health care providers, will provide a basis for addressing the inequities in health care for Indigenous Australians [35] [60]. More accessible and culturally appropriate primary health care might enable Indigenous people with cardiovascular disease to be identified earlier in the course of their illness and have comorbidities treated in a more timely fashion [73]. This would be better achieved by involvement of Indigenous patients in decision making, and greater development of key services including: Aboriginal Health Workers; liaison officers, and particularly interpreter services [48] [58] [49].

The resources required for effective secondary intervention will differ among communities according to the disease burden, and the specific community [39], and can best be determined through consultation with the communities and individuals targeted.

In the case of secondary prophylaxis for rheumatic heart disease (including acute rheumatic fever), adherence to treatment was improved when patients felt a sense of personalised care and 'belonging' to the healthcare service or clinic [46]. It would therefore be beneficial to extend this type of care to Indigenous Australians experiencing any form of cardiovascular disease, and further broaden out to include all chronic disease.

Concluding comments

Indigenous Australians experience poorer cardiovascular health than other Australians. Cardiovascular disease makes a substantial contribution to the disparity in the overall health of Indigenous and non-Indigenous people. Reflecting the higher prevalence of cardiovascular disease among Indigenous Australians, mortality from this disease is also higher among the Indigenous population at a rate between three and four times higher than that of other Australians.

Coronary (ischaemic) heart disease is the leading cause of death for Indigenous Australians, with the differences in death rates between the Indigenous population and non-Indigenous population particularly high in the middle adult years (35-54 years). Cerebrovascular disease (including stroke), follows a similar pattern and is another major contributor to Indigenous mortality in Australia. Deaths from rheumatic heart disease (including acute rheumatic fever) have been recorded for a considerable number of Indigenous Australians; however it remains an uncommon cause of death among the non-Indigenous population.

The factors contributing to the high levels of prevalence of, and hospitalisation and mortality from cardiovascular disease among Indigenous Australians are complex. The high levels of behavioural and biomedical risk factors seen among Indigenous people are clearly associated with the high levels of cardiovascular disease but these factors need to be considered within a social determinants context.

As with other areas of Indigenous health, historical, socio-cultural and economic aspects are the upstream factors within which the behavioural and biomedical risk factors and the actual impacts of cardiovascular disease should be viewed.

The provision of services to Indigenous Australians: preventative; treatment; and rehabilitation for cardiovascular disease, need to be tailored to each unique community in consultation with the people, and health care services of that community. Appropriate services are needed not only for cardiovascular disease, but for each and every potential risk factor, including those of a social determinants nature. Anything less would result in significant gaps in the health and welfare of Indigenous Australians and would only seek to sustain/preserve the current health inequities between Indigenous Australians and other Australians.

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Endnotes

1. The term Indigenous is used in this review to refer generally to the two Indigenous populations of Australia Australian Aboriginal people and Torres Strait Islanders.
2. For jurisdictions with adequate Indigenous identification (NSW, Vic, Qld, WA, SA and the NT, public hospitals only).
3. Details are available for NSW, Vic, Qld, WA, SA and the NT (public hospitals only).
4. The identification of Indigenous people in hospital data is incomplete, so caution must be exercised in the interpretation of information presented here.
5. More recent information on hospitalisation statistics for Indigenous Australians was not readily available due to the recent restructure of the Australian hospitalisation statistics [6].
6. The numbers and ratios quoted in this review have not been adjusted for the likely under-identification of Indigenous people in death registration systems. Due to different methods and levels of identification over time, caution should be exercised when examining deaths, mortality and trends for Indigenous Australians [74].
7. Restricted to people aged 74 years or less living in those jurisdictions in 2002-2006.
8. Restricted to people aged 74 years or less living in those jurisdictions in 2002-2006.
9. It is beyond the scope of this review to detail the data sources for rheumatic heart disease and acute rheumatic fever. Further information on this can be obtained from the Australian Institute of Health and Welfare [7].
10. It is beyond the scope of this review to define the specific conditions of congenital heart disease, for information refer to the AIHW publication [19]
11. The definition of health expenditure changed over this time and therefore caution must be taken when considering this rise.
12. Includes other valvular heart disease.
13. Further information can be obtained through various Australian Institute of Health and Welfare publications [14] [17].
14. Hypertension is a condition of the cardiovascular system, as well as a risk factor for other cardiovascular diseases.
15. Diabetes and chronic kidney disease are both risk factors for cardiovascular disease and individual diseases.
16. It is beyond the scope of this review to provide further details on these guidelines.
17. It is beyond the scope of this review to explain BMI in any further detail. More information can be obtained through the Australian Government Measure up campaign.
18. Such analysis is beyond the scope of this review, which predominantly focuses on modifiable behavioural and biomedical risk factors.

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