Size of the problem

• CVD prevalence of approximately 750,000 Victorians aged 18+ (estimated from self-reported health surveys) with the most common condition being high blood pressure

• CVD is responsible for one-fifth of the total disease burden in Victoria (approximately 130,000 DALYs per annum out of 600,000 DALYs)

• Four-fifths of CVD burden is due to mortality (approximately 14,000 deaths and 110,000 YLL p.a. in Victoria) and CVD is responsible for about one third of the total YLL

• Ischaemic heart disease and stroke are the major contributors to CVD burden, (accounting for 58% and 26% of CVD respectively) and are the top two causes of burden of disease in both males and females in Victoria

Historical trends

• There has been a downward trend in coronary heart disease mortality in Australia in the past three decades (5% per year)

• The reason is uncertain but is likely to be due to a combination of improvements in levels of blood pressure, tobacco smoking and saturated fat, along with improvements in medical care, despite increase in obesity and little change in physical activity

• The gap in CVD death rates between indigenous and non-indigenous Australians, and between rural/remote and metropolitan residents has widened

• Stroke death rates have also decreased markedly over the past three decades

International comparisons

• Although decreasing, CHD death rates remain high compared with many other developed countries (five times that of Japan, twice that of France and higher than countries such as Greece, Italy and the Netherlands)

• While also decreasing, stroke death rates are still higher than in Canada, USA, Switzerland and France

Projections

• If past trends continue (by no means certain or even likely) then the incidence of CVD is predicted to fall, while mortality due to CVD is predicted to decline at an even faster rate

• Total burden of disease (measured in age-standardised DALY rates) in 2016 is predicted to be half that of 1996

• Nevertheless, ischaemic heart disease will continue to cause most years of life lost

• Hospital admissions rates for CVD have not fallen and cost per admission is rising

Special populations

CVD mortality is higher among:

• Males:
  Males are twice as likely to die from CHD than females, with males under 65 experiencing 3-5 times higher death rates than females
• Indigenous Australians:
  Indigenous Australians die from CHD at twice the rate of non-Indigenous Australians, and 6-9 times higher for adults of working age, with no decline occurring in CVD death rates for indigenous males, despite the dramatic decrease in death rates observed in the non-indigenous population
• Rural areas:
  Higher mortality from CVD is partly due to lower SES, but even after controlling for SES, rural residence is significantly associated with mortality from ischaemic heart disease
• Socioeconomically disadvantaged groups:
  • CVD death rates are approximately double in areas of residence with highest SES quintile compared with areas with lowest SES quintile
  • Clear and consistent gradient of increasing standardised CVD death rates (at both high and low ends of the SES scale)
  • CVD death rate gradient persists even when behavioural risk factors are accounted for

Evidence-based interventions

Achievable reductions (5-10 year timeframe) in coronary heart disease events and coronary deaths through more effective population and 'at-risk' group strategies:

• Group I: People with no history of hypertension, high blood pressure or coronary heart disease (72% of persons aged 35-79)
  • 21% of all coronary events occur in Group I
  • 37% reduction in CHD events in Group I estimated to be realistically achievable
    (implies an 8% reduction in CHD events and 7% reduction in CHD deaths in Victoria)

Appropriate strategies that would achieve these health gains in Group I:

• Population average level of cholesterol reduced by 0.5 mmo/L
• Population average level of diastolic blood pressure reduced by 4 mmH
• Prevalence of cigarette smoking halved
• Prevalence of physical inactivity reduced to 25%

• Group II: People with a history of high blood pressure or high blood cholesterol but no known coronary heart disease (23% of persons aged 35-79)
  • 48% of all coronary events occur in Group II
  • 31% reduction in CHD events in Group I estimated to be realistically achievable
    (implies a 15% reduction in CHD events and 13% reduction in CHD deaths)

Appropriate strategies that would achieve these health gains in Group II:

• Levels of cholesterol and blood pressure lowered by drug treatment ('high-risk' group strategy) and by other means (population strategy)
• Population average level of diastolic blood pressure reduced by 4 mmH
• Prevalence of cigarette smoking halved
• Prevalence of physical inactivity reduced to 25%

• Group III: People who have a history of coronary heart disease (5% of persons aged 35-79)
  • 31% of all coronary events occur in Group III
  • 47% reduction in CHD events in Group III estimated to be realistically achievable
    (implies a 15% reduction in CHD events and 17% reduction in CHD deaths

Appropriate strategies that would achieve these health gains in Group III:

• More extensive use of coronary bypass surgery and coronary angioplasty for revascularisation
• Lowering cholesterol and blood pressure, by drug treatment in half those with elevated levels but who are not already being treated
• By diet and other means in the rest
• Higher use of aspirin and other drugs, such as beta blockers and ACE inhibitors
• Reductions in levels of cigarette smoking and physical inactivity

Reductions in stroke events are also achievable through strategies such as:

• Primary prevention: Population health promotion efforts to lower average blood pressure (through reducing salt intake, alcohol consumption and body weight), reduction of smoking levels, alcohol abuse and saturated fat intake (particularly in the young)
• Acute management: Coordinated multidisciplinary team in a stroke unit
• Secondary prevention:
  • identification and anticoagulation therapy for those with atrial fibrillation (most important
  • blood pressure lowering drug therapy
  • smoking cessation
  • cholesterol lowering drug therapy with statin
  • carotid endarterectomy (least important)

CVD risk factors

1. Downstream (biomedical/physiological)
   • excess weight; high blood pressure
   • high blood cholesterol
   • release of stress hormone (e.g. cortisol)
   • "metabolic syndrome"
   • diabetes mellitus
   • non-valvular atrial fibrillation (stroke only)
   • transient ischaemic attack (stroke only)
2. Midstream
   • Behavioural: Poor diet; physical inactivity; tobacco use; alcohol misuse
   • Psychosocial: Low perceived control; isolation; lack of social support; loss of meaning or purpose
   • Demographic/socio-economic: Low SES; Indigenous; CALD; Rural/remote residence
   • Health services: Preventative services; access to effective and culturally appropriate primary health services
3. Upstream (physical/social environmental conditions; broader determinants of health)
   • Social capital
   • Civic engagement
   • Income inequality
   • Government policies

Related health issue – Metabolic Syndrome

A clustering of metabolic problems associated with insulin resistance, including elevated plasma glucose, lipid regulation problems (elevated triglycerides, increased small low-density lipoproteins, and decreased high-density lipoproteins), high blood pressure, a prothrombic state, and obesity (especially central obesity) occurs commonly together.

This combination is referred to as either "The Metabolic Syndrome" or "Syndrome X." Research suggests this cluster of metabolic disorders seems to interact to promote the development of type 2 diabetes, atherosclerosis, and cardiovascular disease.

The social gradient in prevalence of the metabolic syndrome is consistent with the 'allostatic load' hypothesis* which links the psychosocial environment to physical disease via neuroendocrine pathways.

* McEwen, B.S. (1998). Protective and damaging effects of stress mediators. N. Engl. J. Med. 338, 171-9

References