*Medical Student, ANU
Ischaemic heart disease (IHD) and diabetes are chronic conditions contributing substantially to the total burden of disease and injury in Australia. They are associated with significant morbidity and mortality requiring complex and expensive treatment plans. The Australian Aboriginal and Torres Strait Islander (Indigenous) population have higher prevalence rates for both diseases and have significantly worse disease outcomes than non-Indigenous Australians. The discrepancy in disease outcomes is partly due to the lower uptake of procedure rates and the higher rates of early discharge from hospital against medical advice by Indigenous Australians. Risk factors for IHD and diabetes overlap significantly and are mostly modifiable at the individual, community or population level. Prevention strategies for IHD and diabetes would largely be focussed on mitigating risk factors and would involve prevention strategies at multiple levels. One such strategy would focus upon the following factors: transport, housing, food provision and affordability, education, access to health care, implementation of screening programs and employment of Aboriginal health workers to help bridge the gap between Indigenous and non-Indigenous cultures.
The Aboriginal and Torres Strait Islander (Indigenous) population suffer the highest prevalence of ischaemic heart disease (IHD) and diabetes in Australia (figures 1 and 2) and some of the highest levels of morbidity in the world1. IHD is the most common form of cardiovascular pathology and the leading cause of death for Australians (both Indigenous and non-Indigenous)2. However Indigenous Australians have twice the risk of having IHD3 and five to ten times the risk of having type 2 diabetes compared to non-Indigenous Australians1, 4. IHD refers to conditions in which the blood supply to parts of the heart is compromised. The major clinical manifestations of IHD are angina pectoris, myocardial infarction (MI) and heart failure5. In angina pectoris, the blockage to the blood supply is only temporary, resulting in chest pain on exertion. In the case of acute MI, the interrupted blood supply is due to complete blockage of one of the coronary arteries6. Diabetes is a chronic disease characterised by inadequate glucose homeostasis resulting in hyperglycaemia, caused by insufficient insulin secretion and/or insulin resistance7. If not managed effectively, the macrovascular, microvascular and metabolic complications of diabetes can be a major cause of morbidity and mortality.
Figure 1. Prevalence of cardiovascular disease by age and Indigenous status, 2004-20053
|Figure 2. Prevalence of cardiovascular disease by age and Indigenous status, 2004-20053
Source: Adapted from Australian Institute of Health and Welfare 20083
Epidemiology and Burden of Disease
The “Burden of Disease and Injury in Australia 2003” study conducted by the Australian Institute of Health and Welfare found that IHD was responsible for 3.3% of years of ‘healthy’ life lost due to disability (YLD), 17.1% of years of life lost due to mortality (YLL) and 10% of disability-adjusted life years (DALYs)5. Diabetes was found to be responsible for 6.6% of YLD, 2.5% of YLL and 4.6% of DALYs. Together, these two diseases represent a significant contribution to the total burden of disease and injury in Australia. In the Indigenous Australian population however, IHD and diabetes represent an even larger contribution to the total burden of disease and injury with IHD accounting for 10.4% of DALYs and diabetes accounting for 8.2% of DALYs8. This disparity is further demonstrated by a study conducted in three remote communities in the Northern Territory that found the prevalence of diabetes to be 17-30% among Indigenous Australians4. According to the 2004-05 National Health Survey ~3.2% of the Australian population have IHD with the prevalence for males three times greater than that for females9. The prevalence was also found to increase with age: 7.6% of people aged 55-64 reported having IHD while 20.3% of those 75 and above reported having a diagnosis of IHD. The age-standardised prevalence rate for IHD is twice as high for Indigenous as it for non-Indigenous Australians3. Indigenous Australians are also three times more likely to have a major coronary event than non-Indigenous Australians, largely due to the earlier age of onset2.
Complications arising from diabetes can be grouped into macrovascular conditions (e.g. IHD, peripheral vascular disease, hypertension and stroke)10-13, microvascular damage (e.g. nephropathy, retinopathy and neuropathy)14-15 and metabolic complications of glucose homeostasis (e.g. diabetic coma)16. Managing these diabetic complications can be very expensive for the healthcare system. The DiabCost Australia study found that an average of $11,000 was being spent on each diabetic per year, amounting to ~3 billion dollars per year17. Complex disease management using a multidisciplinary team is needed to treat diabetes effectively, partly explaining the high costs (figure 2). Multidisciplinary care for diabetes ideally includes regular consultations with a diabetic educator, GP, optometrist or ophthalmologist, podiatrist, and if necessary, a cardiologist. However, the high costs involved in the effective management of diabetes are easy to justify when considering the huge financial burden that arises from poorly managed diabetes. For example, dialysis is the treatment for chronic renal failure (a common complication from poorly controlled diabetes), which costs ~$100,000 per year18. This reinforces the necessity of preventative health care.
Management of IHD is also costly and consumes a relatively large proportion of the Australian health budget. Direct healthcare expenditure on IHD was $894 million (2.8% of total health expenditure) in 1993-199419. The age-adjusted rate ratio for percutaneous coronary interventions (PCI), also known as angioplasty, is 40% lower for Indigenous than non-Indigenous Australians while that for coronary artery bypass graft (CABG) procedures is 20% lower2. Possible reasons for the difference in procedure rates is that Indigenous people are more likely to discharge themselves prematurely from hospital20 and perceived lack of compliance by Indigenous individuals2. Suggestions to rectify this issue include a greater respect for cultural appropriateness of services, better communication and explanation of treatment options21.
|Figure 3. Cost Breakdown of Factors Associated with Management of Type 2 diabetes17
Source: Adapted from Diabetes Australia 200317
Risk factors for IHD overlap significantly with those for diabetes; indeed diabetes is itself a risk factor for IHD3, 22. A non-exhaustive list of non-modifiable risk factors for both conditions include: genetic predisposition3, 23-25, increased age3, 22, 26, low birth weight (LBW)25, 27 and gestational diabetes mellitus (GDM)28, 29. If addressed early, LBW and GDM become partially modifiable risk factors. If the mother maintains good health during pregnancy, eating a healthy diet and not engaging in substance abuse; the probability that her child will have a LBW is significantly reduced30. Thus the child’s risk of developing IHD and diabetes is decreased. Similarly, there are a number of management strategies to reduce morbidity of GDM31 that decrease the mother and child’s future risk of disease.
There are also many modifiable risk factors for IHD and diabetes, the most important of which being increased body mass index (BMI)3, 32, 33. In 1999-2000, it was found that 60% of Australians were overweight or obese, representing a more than two-fold increase over two decades34. Amongst Indigenous Australians 29% were found to be overweight, and 31% obese35. The two main causes of high BMI are low levels of physical activity3, 36-38 and poor nutrition3, 38-40. Furthermore, the risk of developing these diseases has been found to be reduced through light to moderate exercise; for example, walking around the house36,38,40. Smoking has long been established as another modifiable risk factor for IHD3,22 and diabetes41. While it has been posited that moderate consumption of alcohol may decrease the risk of developing type 2 diabetes42 and IHD43, several studies have found that high consumption of alcohol increases the risk for both diseases22, 42, 44. Low socio-economic status has been established as another independent risk factor for IHD3 and diabetes within the Indigenous Australian population45. Contributing factors include poverty, inadequate housing, low income and difficulty establishing employment3, 46.
Prevention Strategies and Practical Application
Table 1. Strategies at the four levels of prevention to minimise morbidity and mortality from IHD and diabetes among Indigenous Australians.
|Diabetes & IHD||Primordial||Transport||Transport providing access to: health care, healthy food, educational institutions & areas providing employment is of high priority54.|
|Appropriate housing & sanitation||Only 33% of permanent houses were found to have a septic system in a study conducted in discreet Indigenous communities46. Other studies have found houses to be kept in a state of disrepair and overcrowding to be an issue55. These factors pose considerable health risks.|
|Healthy foods||Community-centred approaches involving increasing supply and demand for healthy foods have achieved positive outcomes in Indigenous communities49.|
|Education||Positive correlations between life expectancy and level of education have been established, with life expectancy increasing by 5-15 years for people who have completed higher education56,57. Health education including healthy eating should also be addressed.|
|Exercise programs||Community-based exercise programs would provide a means for individuals to become more active, contributing to lower BMI. This could be provided through the school setting58.|
|Access to health care||For any primary, secondary or tertiary prevention strategy to work, easy access to health care is required.|
|Culture gap||Aboriginal health workers can help Indigenous patients to provide informed consent, have better understanding of medical procedures and have knowledge of community rehabilitation programs52.|
|Access to medication||Access to medications is vital for primary, secondary and tertiary prevention of IHD (e.g. statins, ACE inhibitors, anti-platelet agents, anti-hypertensive agents)59 and diabetes (e.g. sulfonylureas, metformin, insulin).|
|Health education||Health education regarding: nutrition, when to seek medical assistance, risk factors and self-management of IHD and diabetes are vital60.|
|Lifestyle changes||↑ physical activity and eating healthier foods (↓ energy foods with ↑ nutritious value) will ↓ the risk of IHD37, 40 and diabetes61.|
|Health care||As above|
|Culture gap||As above|
|Screening programs||Providing free urine dipstick testing, glucose tolerance testing and access to an ECG machine to Indigenous Australians. These could be provided through the GP setting, ensuring that skilled personnel are available to interpret results. Efficacy of such programs is reliant on communities being aware that such facilities are available.|
|Health care||Access to health care is very important for tertiary prevention. In the case of diabetes, regular consultations with the GP, podiatrist, optometrist and other allied health professionals is required to reduce the risk of diabetes-associated complications. This is equally important in IHD as early intervention can halt the progression from angina pectoris to MI.|
|Culture gap||As above|
In order to implement a cost-effective, practical prevention strategy that could be used in Northern Queensland to minimise morbidity and mortality from IHD and diabetes, a multidisciplinary approach would ideally be used, first looking at primordial prevention. Due to the large number of remote communities in this area, an immediate area of priority is transport. Transport should be put in place to provide better access to health care facilities, nutritious food, educational institutions and areas offering employment. This infrastructure would also make it easier for health professionals to visit remote communities, making health care more accessible.
Next, resources should be allocated to establishing culturally and environmentally appropriate housing for Indigenous Australians. Sewerage and irrigation must also be considered. There is a strong correlation between poor housing quality and negative health outcomes such as chronic disease, infectious diseases, poor nutrition, mental disorders and increased rates of injury47. Hallmarks of inadequate housing include “lack of safe drinking water, absence of hot water for washing, ineffective waste disposal, intrusion by disease vectors (e.g., insects and rats) and inadequate food storage”47.
After transport and housing have been addressed, methods of providing affordable and healthy foods should be considered. In order to provide culturally-acceptable, nutritious foods, it has been suggested that the food systems of Indigenous peoples should be investigated48. Community-centred approaches that have been effective involved increasing supply of and demand for healthy foods. This was achieved through community education about the health benefits of a balanced diet and stock management49.
Finally, education should be addressed. Education programs that have been found to be extremely effective in Indigenous communities take a holistic approach incorporating multiple school bus runs, provision of food, provision of clothing if required and a curriculum incorporating conventional and Indigenous education50. The school environment would provide an effective platform to promote health education including hygiene, nutrition, food preparation and when to seek medical assistance. It is also possible that children could pass this knowledge on to other members of the community. At the community level, lifestyle modification initiatives should also be devised focussing on healthy eating, becoming more active, smoking cessation and alcohol cessation. This could be in the form of posters, free information sessions and advertising campaigns. One strategy to increase the level of activity could be to provide pedometers to Indigenous individuals and set a goal of achieving a certain number of steps per day.
While primordial prevention is based on preventing risk factors at the community or population level, primary prevention strategies can be aimed at the individual level. At this level, the main focus is still on mitigation of risk factors but a greater emphasis should be placed upon access to health care and medications. One strategy that has been found to be invaluable in bridging the cultural gap between Indigenous and non-Indigenous culture is the use of Aboriginal health workers (AHW)51,52. Under supervision, and with the appropriate training, AHWs can administer vaccinations, perform venepuncture, perform Pap smears and perform basic health checks51. The appointment of an AHW to a cardiac ward in a tertiary hospital in Western Australia was found to deliver more effective health education and care, reduce rates of discharge against medical advice, increase time for Indigenous patient contact and generally create a more comfortable hospital environment for Indigenous Australians52.
Secondary prevention strategies rely on the early detection of disease. As such, screening programs are highly useful. Ideally, these would be conducted through the GP setting with the presence of an AHW to assist with communication. These screening programs would involve: measurement of height, weight and blood pressure, urine dipstick testing and spot blood glucose testing. A targeted history should also be conducted, focussing upon eliciting symptoms of IHD and peripheral vascular disease such as chest pain and claudication. If diabetes is suspected, oral glucose tolerance testing should be available. Similarly, if IHD is suspected, an ECG machine should be available. If early signs of either disease are found, management should start immediately. Information regarding the importance of compliance to treatment regimens should also be provided to prevent disease progression.
Tertiary prevention strategies rely heavily upon health professionals and could be facilitated through the use of an AHW. In order to effectively manage IHD and diabetes, regular consultations with a range of health professionals are required. This reinforces the importance of access to primary health care and health education.
IHD and diabetes represent a substantial percentage of the total burden of disease and injury in Australia. In the total Australian population, these two diseases represented approximately 15% of DALYs in 2003. When looking at the Indigenous population alone, these diseases were responsible for closer to 19% of DALYs. Effective management of these diseases is costly and requires a high degree of compliance with treatment plans. While prevalence is higher among the Indigenous Australian population, uptake of procedure rates is considerable lower than in non-Indigenous populations. Reasons for the discrepancy in procedure rates have been attributed to perceived lack of compliance, which may be the result of inadequate health education regarding the condition, and premature discharge from hospital against medical advice. Employment of an AHW has been shown to provide better outcomes regarding both of these factors. Prevention strategies have been discussed above and there is much opportunity to implement change at multiple levels.