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Cardiovascular disease

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Cardiovascular disease

Cardiovascular disease (CVD; ICD 'Diseases of the circulatory system') includes all diseases and conditions that affect the heart and blood vessels [1]. CVD presents a significant burden for Aboriginal and Torres Strait Islander people in terms of prevalence, hospitalisation, and mortality [2][3]. This is evident for a range of CVDs including CHD (or ischaemic heart disease), cerebrovascular disease (including stroke), hypertension (high blood pressure), and rheumatic heart disease (RHD).

Most types of CVD (excluding RHD) are subject to the same set of modifiable or non-modifiable risk factors [4]. Modifiable behavioural factors for CVD include tobacco use, physical inactivity, poor dietary behaviour, and excessive alcohol consumption [4][5]. Modifiable biomedical factors include hypertension, high blood cholesterol, overweight and obesity, and depression. Certain related health conditions, particularly diabetes and chronic kidney disease, can also increase the risk of developing CVD. Non-modifiable risk factors that can influence the risk of CVD include, age, sex, family history, and ethnicity.

Unlike other types of CVD, RHD occurs when acute rheumatic fever (ARF)—an illness that affects the heart, joints, brain and skin—leads to permanent damage to the heart valves [6][7]. ARF, which is rare among non-Indigenous Australians, is caused by an untreated bacterial (group A streptococci or GAS) throat infection.1 Reducing ARF and RHD in Aboriginal and Torres Strait Islander communities requires initiatives that address poverty, overcrowded housing and poor sanitation, all of which contribute to the spread of GAS infection.

The persistence of ARF in Aboriginal and Torres Strait Islander communities highlights the impact of social determinants of health that underpin RHD [8][9]and CVD more broadly.2 As with other areas of health, reducing the burden of CVD will require efforts to address the social, economic and environmental inequities that Aboriginal and Torres Strait Islander people experience.

Extent of cardiovascular disease among Aboriginal and Torres Strait Islander people
Prevalence of cardiovascular disease

Around 13% of Aboriginal and Torres Strait Islander people aged 2 years and over reported in the 2012-2013 Aboriginal and Torres Strait Islander health survey (AATSIHS) that they had some form of CVD3 [3]. When the data for Aboriginal people4 and Torres Strait Islander people5 were analysed separately, the levels of CVD were similar (13% and 12% respectively) [10].

CVD was reported more frequently by Aboriginal and Torres Strait Islander females (14%) than by Aboriginal and Torres Strait Islander males (11%) [11]. After age-adjustment, CVD was reported 1.2 times more frequently by Aboriginal and Torres Strait Islander people than by non-Indigenous people. CVD increased with age for both Aboriginal and Torres Strait Islander and non-Indigenous people; the prevalence was higher for Aboriginal and Torres Strait Islander people than for non-Indigenous people in all age-groups except those aged 55 years or older (Figure 2) [12]. Aboriginal and Torres Strait Islander people living in remote areas were more likely to report having heart disease than those living in non-remote areas (18% and 11% respectively) [13].

Figure 2. Prevalence (%) of people reporting cardiovascular disease as a long-term health condition, by Indigenous status and age-group, Australia, 2012-2013

Note: Prevalences are expressed as percentages

Source: ABS 2014 [12]

Hypertensive heart disease was the form of CVD most commonly reported by Aboriginal and Torres Strait Islander people (5.8%) in 2012-2013 [11]. After age-adjustment, the prevalence of hypertensive heart disease among Aboriginal and Torres Strait Islander people was similar to that among non-Indigenous people (Table 17). The greatest disparities in prevalence between Aboriginal and Torres Strait Islander and non-Indigenous males and females were for ‘Heart, stroke and vascular diseases’6 (age-adjusted ratios of 1.5 for males and 1.7 for females).

Table 17. Prevalence (%) of cardiovascular disease, Indigenous people by sex and type, and Indigenous:non-Indigenous age-adjusted rate ratios, Australia, 2012-2013

Cardiovascular disease type

Males

Females

Prevalence

Rate ratio

Prevalence

Rate ratio

Hypertensive heart disease

5.6

1.0

6.0

1.1

Heart, stroke and vascular diseases

4.0

1.5

3.8

1.7

All cardiovascular disease

11.1

1.2

14.2

1.3

Note: Prevalences are expressed as percentages

Source: ABS, 2014 [11]

Around 4% of Aboriginal and Torres Strait Islander people reported that they had ‘Heart, stroke and/or vascular diseases’ in 2012-2013 [3]. Heart disease, stroke and/or vascular diseases were reported in almost the same proportions by Aboriginal and Torres Strait Islander males and females (4.0% and 3.8% respectively) [11]. These diseases were prevalent from about 35 years of age onwards; 4.2% of Aboriginal and Torres Strait Islander people aged 35-44 years reported heart, stroke and/or vascular disease, compared with 10% of those aged 45-54 years and 20% of those aged 55 years and over [12].

Around 6% of Aboriginal and Torres Strait Islander people (5.8% of Aboriginal people and 5.3% of Torres Strait Islander people [10]) reported that they had hypertensive heart disease [3]. Hypertensive heart disease was reported in almost the same proportions by Aboriginal and Torres Strait Islander males and females (5.6% and 6.0% respectively) [11]. Hypertensive disease increased in prevalence from about 25 years of age onwards; 12% of Aboriginal and Torres Strait Islander people aged 25 years and over reported hypertensive heart disease [3]with proportions ranging from 4.1% of those aged 25-34 years to 25% of those aged 55 years and over [12].

The 2012-13 AATSIHS also provided data for selected risk factors for CVD [3]. These self-reported results were supplemented—for the first time—by biomedical results obtained from a subset of Aboriginal and Torres Strait Islander adults (18 years and over) who provided blood and urine samples [14]. The self-reported [3] and biomedical results [14] show that some CVD risk factors are more prevalent among Aboriginal and Torres Strait Islander people than among their non-Indigenous counterparts, including: daily smoking (rate ratio 2.6 7); obesity (rate ratio 1.6 7); inadequate daily fruit and vegetable intake (rate ratios 0.9 7 and 0.819respectively for meeting the guidelines); high blood pressure (rate ratio 1.2 8); abnormal high density lipoprotein (HDL) cholesterol (rate ratio 1.8 8); high triglycerides (rate ratio 1.9 8); and dyslipidaemia (rate ratio 1.1 8).

Prevalence of rheumatic heart disease and incidence of acute rheumatic fever

Jurisdictional data for the prevalence of RHD and the incidence of ARF are currently only available from the NT, Qld and WA Rheumatic Heart Disease Registers, with a register for SA currently under development [15]. It is not possible to directly compare data from these registers9 but, despite low rates of RHD and ARF in Australia, it is clear that these diseases are disproportionately represented in the Aboriginal and Torres Strait Islander population.

The most recent data for RHD is for Qld at 1 July 2014, where of the recorded cases (1,035), 89% were Aboriginal and Torres Strait Islander people [16]. After age-adjustment the prevalence of RHD among Aboriginal and Torres Strait Islander people was 206 times higher than non-Indigenous people. Almost two-thirds (64%) of the Aboriginal and Torres Strait Islander people with RHD were females, with the highest number of cases (159 cases) in the 25-34 age-group, 733 times the rate of non-Indigenous females in this age-group. Aboriginal and Torres Strait Islander males made up just over one third (36%) of the Aboriginal and Torres Strait Islander cases of RHD, with the highest prevalence (120 cases) being in the 15-24 years age-group, 135 times the rate of non-Indigenous males [16]. However, the greatest disparity in prevalence between Aboriginal and Torres Strait Islander males and non-Indigenous males was in the 25-34 years age-group (308 times).

Of the recorded cases of RHD in the NT (1,573 at 31 December 2013), 94% were Aboriginal and Torres Strait Islander people [16]. After age-adjustment, the prevalence of RHD among Aboriginal and Torres Strait Islander people was 40 times higher than among other Australians. Two thirds (65%) of the Aboriginal and Torres Strait Islander people with RHD were females and around one-third (35%) were males. The prevalence of RHD in Aboriginal and Torres Strait Islander people was highest in the 45+ year age-group (26%), 22 times the rate of non-Indigenous people. The disparity in prevalence between Aboriginal and Torres Strait Islander people and non-Indigenous people was highest in the 25-34 years age-group, however (rate ratio: 164.5).

Detailed data for WA are not available for 2013, however there were 305 cases of RHD among Aboriginal and Torres Strait Islander people at 31 December 2013 [16]. The prevalence of RHD was highest in the 15-24 years age-group (24%).

Over the period 2010-13, of 787 total recorded cases of ARF in the NT, WA and Qld, 743 were Aboriginal and Torres Strait Islander people, with the prevalence of ARF being 329 times higher than that of non-Indigenous people. Cases of ARF in the NT (330), Qld (196) and WA (217) were 97%, 86% and 99% respectively for Aboriginal and Torres Strait Islander people [16]. As is the case for RHD, ARF incidence (new and recurrent cases) was higher in Aboriginal and Torres Strait Islander females than males (393 and 350 cases respectively).

The incidence of ARF in Qld, WA and the NT (combined) was highest in the 5-14 years age-group for both Aboriginal and Torres Strait Islander males (206 cases; 1.2 per 1,000) and females (180 cases; 1.1 per 1,000) [16].

Hospitalisation

There were 11,868 hospital separations for diseases of the circulatory system among Aboriginal and Torres Strait Islander people living in Australia in 2013-14, accounting for 2.9% of separations identified as Aboriginal and Torres Strait Islander [17]. Aboriginal and Torres Strait Islander people were hospitalised with a primary diagnosis of CVD at almost two times the rate of non-Indigenous people (31 compared with 18 per 1,000 population) [18].

In comparison with previous years, the rate of Aboriginal and Torres Strait Islander people hospitalised for CVD increased by 12%, from 28 per 1,000 in 2004-2005 to 32 per 1,000 in 2013-14 [18]. During this same period, the rate of non-Indigenous people hospitalised for CVD declined by 15%. The leading causes of CVD hospitalisations were CHD (40%: 4,771 hospitalisations) heart failure and cardiomyopathy (15%: 1,730 hospitalisations), stroke (7%: 838 hospitalisations), peripheral vascular disease (4%: 420 cases), ARF and RHD (4%: 516 hospitalisations) and hypertensive heart disease (3%: 356 hospitalisations).

There were 6,289 hospitalisations of Aboriginal and Torres Strait Islander males with CVD as the primary diagnosis, who were hospitalised at 1.6 times the rate of non-Indigenous males (35 per 1,000 and 22 per 1,000 respectively) [18]. The hospitalisation rate for Aboriginal and Torres Strait Islander females was 2.1 times higher than the rate for non-Indigenous females (28 per 1,000 and 14 per 1,000 respectively). In all age-groups, except for males aged 75 and over, Aboriginal and Torres Strait Islander people were hospitalised at higher rates than non-Indigenous people. The gap was highest in the 35-44 and 45-54 years age-groups, with Aboriginal and Torres Strait Islander people hospitalised at three times the rate of non-Indigenous people. Hospitalisation rates for CVD for Aboriginal and Torres Strait Islander people were highest in remote and very remote areas (41 per 1,000 population), 1.7 times higher than in major cities (25 per 1,000 population).

Mortality

CVD was the leading cause of death of Aboriginal and Torres Strait Islander people in 2013, being responsible for 24% (636) of the deaths in this population [19]. Of the various types of circulatory diseases, ischaemic heart diseases10 were the leading cause of death for Aboriginal and Torres Strait Islander people (321 deaths) in 2013, followed by cerebrovascular diseases11 (122 deaths). Ischaemic heart diseases were also the overall leading cause of death for Aboriginal and Torres Strait Islander people, accounting for around 12% of all deaths [20]. After age-adjustment, death rates from ischaemic heart diseases and cerebrovascular diseases were both 1.6 times higher for Aboriginal and Torres Strait Islander people than for non-Indigenous people. There were more deaths from ischaemic heart diseases among Aboriginal and Torres Strait Islander males (204) than among Aboriginal and Torres Strait Islander females (117), but more Aboriginal and Torres Strait Islander females (70) died from cerebrovascular diseases than Aboriginal and Torres Strait Islander males (52). Aboriginal and Torres Strait Islander males were more likely to die from ischaemic heart diseases and cerebrovascular diseases than non-Indigenous males (both rate ratios 1.6) and Aboriginal and Torres Strait Islander females were more likely to die from these diseases than non-Indigenous females (both rate ratios 1.6).

Despite disproportionately high death rates for CHD among Aboriginal and Torres Strait Islander people, there has been an improvement in the overall CHD mortality gap between 2001-2002 and 2009-2010 [21]. This is due in large part to declines in CHD mortality among Aboriginal and Torres Strait Islander women, particularly those in the age-groups 40-54 years and 70 years and over.

Avoidable mortality data12 is available for the period 2008-2012 for Aboriginal and Torres Strait Islander people in NSW, Qld, WA, SA and the NT [2]. There were 92 potentially avoidable deaths from rheumatic and other valvular heart disease among Aboriginal and Torres Strait Islander people in this period. After age-adjustment, potentially avoidable deaths from rheumatic and other valvular heart disease were 12.4 times more common for Aboriginal and Torres Strait Islander people than for non-Indigenous people.

In 2010-12, there were 61 deaths of Aboriginal and Torres Strait Islander people in NSW, Qld, WA, SA and the NT due to RHD/ARF, which accounted for 3% of CVD deaths for Aboriginal and Torres Strait Islander people, compared to less than 1% for non-Indigenous CVD deaths [18]. More detailed RHD data are available for the period 2006-2010, when RHD was responsible for the deaths of 90 Aboriginal and Torres Strait Islander people in the same jurisdictions [22]. The age-adjusted death rate for Aboriginal and Torres Strait Islander people was 4.7 times that of non-Indigenous people. Both Aboriginal and Torres Strait Islander males and females were more likely to die from RHD than their non-Indigenous counterparts (3.5 and 5.3 times respectively).

The striking difference between Aboriginal and Torres Strait Islander people and non-Indigenous people in CVD mortality is the much greater impact among young and middle-aged Aboriginal and Torres Strait Islander adults. In 2010-12 in NSW, Qld, WA, SA and the NT, the death rate for CHD (the leading cause of CVD-related deaths) was 10 times higher for Aboriginal and Torres Strait Islander men and women in the 35-44 years age-group than for their non-Indigenous counterparts [18].

References

  1. Baker IDI (2012) Cardiovascular disease. Retrieved 2012 from http://www.bakeridi.edu.au/health_fact_sheets/cardiovascular_disease/
  2. Steering Committee for the Review of Government Service Provision (2014) Overcoming Indigenous disadvantage: key indicators 2014. Canberra: Productivity Commission
  3. Australian Bureau of Statistics (2014) Australian Aboriginal and Torres Strait Islander health survey: updated results, 2012–13. Canberra: Australian Bureau of Statistics
  4. Australian Institute of Health and Welfare (2011) Cardiovascular disease: Australian facts 2011. Canberra: Australian Institute of Health and Welfare
  5. World Heart Federation (2012) Cardiovascular disease risk factors. Retrieved 2012 from http://www.world-heart-federation.org/cardiovascular-health/cardiovascular-disease-risk-factors/
  6. Australian Institute of Health and Welfare (2013) Rheumatic heart disease and acute rheumatic fever in Australia: 1996-2012. Canberra: Australian Institute of Health and Welfare
  7. Rheumatic Heart Disease Australia, National Heart Foundation of Australia, Cardiac Society of Australia and New Zealand (2012) The Australian guideline for prevention, diagnosis and management of acute rheumatic fever and rheumatic heart disease: 2nd edition. Winnellie, NT: Menzies School of Health Research
  8. Maguire GP, Carapetis JR, Walsh WF, Brown ADH (2012) The future of acute rheumatic fever and rheumatic heart disease in Australia [editorial]. Medical Journal of Australia; 197(3): 133-134
  9. Murdoch J, Davis S, Forrester J, Masuda L, Reeve C (2015) Acute rheumatic fever and rheumatic heart disease in the Kimberley: using hospitalisation data to find cases and describe trends. Australian and New Zealand Journal of Public Health; 39(1): 38–43
  10. Australian Bureau of Statistics (2014) Australian Aboriginal and Torres Strait Islander health survey: updated results, 2012-13 - Australia: table 21.3 [data cube]. Retrieved 6 June 2014 from http://www.abs.gov.au/AUSSTATS/subscriber.nsf/log?openagent&472705500621.xls&4727.0.55.006&Data%20Cubes&166861F2585F8D85CA257CEE0010DAE7&0&2012%9613&06.06.2014&Latest
  11. Australian Bureau of Statistics (2014) Australian Aboriginal and Torres Strait Islander health survey: updated results, 2012-13 - Australia: table 5.3 [data cube]. Retrieved 6 June 2014 from http://www.abs.gov.au/AUSSTATS/subscriber.nsf/log?openagent&472705500605.xls&4727.0.55.006&Data%20Cubes&A95A701E3429A625CA257CEE0010D780&0&2012%9613&06.06.2014&Latest
  12. Australian Bureau of Statistics (2014) Australian Aboriginal and Torres Strait Islander health survey: updated results, 2012-13 - Australia: table 6.3 [data cube]. Retrieved 6 June 2014 from http://www.abs.gov.au/AUSSTATS/subscriber.nsf/log?openagent&472705500606.xls&4727.0.55.006&Data%20Cubes&7F2DBD07A515E7A2CA257CEE0010D7BF&0&2012%9613&06.06.2014&Latest
  13. Australian Bureau of Statistics (2014) Australian Aboriginal and Torres Strait Islander health survey: updated results, 2012-13 - Australia: table 2.3 [data cube]. Retrieved 6 June 2014 from http://www.abs.gov.au/AUSSTATS/subscriber.nsf/log?openagent&472705500602.xls&4727.0.55.006&Data%20Cubes&A0A5C6AE5F15C5DECA257CEE0010D6DC&0&2012%9613&06.06.2014&Latest
  14. Australian Bureau of Statistics (2014) Australian Aboriginal and Torres Strait Islander health survey: biomedical results, 2012-13. Canberra: Australian Bureau of Statistics
  15. Australian Health Ministers' Advisory Council (2015) Aboriginal and Torres Strait Islander health performance framework 2014 report. Canberra: Department of the Prime Minister and Cabinet
  16. Australian Institute of Health and Welfare (2015) Aboriginal and Torres Strait Islander health performance framework 2014: data tables. Retrieved 11 June 2015 from http://www.aihw.gov.au/indigenous-data/health-performance-framework/
  17. Australian Institute of Health and Welfare (2015) Admitted patient care 2013–14: Australian hospital statistics. Canberra: Australian Institute of Health and Welfare
  18. Australian Institute of Health and Welfare (2015) Cardiovascular disease, diabetes and chronic kidney disease - Australian facts: Aboriginal and Torres Strait Islander people. Canberra: Australian Institute of Health and Welfare
  19. Australian Bureau of Statistics (2015) Causes of death, Australia, 2013. Canberra: Australian Bureau of Statistics
  20. Australian Bureau of Statistics (2015) Causes of death, Australia, 2013: Deaths of Aboriginal and Torres Strait Islander Australians [data cube]. Retrieved 31 March 2015 from http://www.abs.gov.au/ausstats/subscriber.nsf/log?openagent&3303_12%20%20deaths%20of%20aboriginal%20and%20torres%20strait%20islander%20australians.xls&3303.0&Data%20Cubes&4D9A9ADDB3C2F0ACCA257E18000F913C&0&2013&31.03.2015&Latest
  21. Australian Institute of Health and Welfare (2014) Trends in coronary heart disease mortality: age groups and populations. Canberra: Australian Institute of Health and Welfare
  22. Australian Institute of Health and Welfare (2013) Aboriginal and Torres Strait Islander health performance framework 2012: detailed analyses. Canberra: Australian Institute of Health and Welfare

Endnotes

1. Some research suggests that ARF might also be caused by a streptococcal skin infection.

2. The effects of social determinants on Indigenous health are described in the section ‘The context of Aboriginal and Torres Strait Islander health’.

3. Includes hypertensive disease; ischaemic heart diseases; other heart diseases; tachycardia; cerebrovascular diseases; oedema; diseases of the arteries; arterioles and capillaries; diseases of the veins, lymphatic vessels, etc; other diseases of the circulatory system; and symptoms and signs involving the circulatory system.

4. People of Aboriginal origin only.

5. People of Torres Strait Islander origin only or both Aboriginal and Torres Strait Islander origin.

6. Which include ischaemic heart disease, stroke and other cerebrovascular disease, odema, heart failure, and disease of the arteries, arterioles and capillaries.

7. For Aboriginal and Torres Strait Islander people aged 15 years and over.

8. For Aboriginal and Torres Strait Islander people aged 18 years and over

9. It is not possible to directly compare data from the NT, WA and Qld as the registers are at different stages of establishment and coverage.

10. Ischaemic heart diseases include angina, blocked arteries of the heart and heart attacks.

11. Cerebrovascular diseases include haemorrhages, strokes, infarctions and blocked arteries of the brain.

12. Mortality data associated with potentially preventable and treatable conditions for people aged less than 75 years.

 
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