1301.0 - Year Book Australia, 2003

ARCHIVED ISSUE Released at 11:30 AM (CANBERRA TIME) 24/01/2003

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Cardiovascular disease: 20th century trends

Behavioural changes and medical advances have reduced the likelihood of people dying from cardiovascular disease over the last 30 years. Yet cardiovascular disease was still the leading cause of death in Australia in 2000, accounting for 49,687 deaths (39% of all deaths registered in that year). Because much illness and premature death from cardiovascular disease is preventable, it has been a focus of public attention and health policy, and in 1996 was designated a National Health Priority Area (AIHW 2000c).

Although cardiovascular disease can be a disease and cause of death at younger ages, a much higher proportion of older people are affected by cardiovascular disease. In 2000 the majority of deaths from cardiovascular disease occurred among those aged 50 years and over. Early in the 20th century, Australia's population had a young age structure and the proportion of deaths from cardiovascular disease was relatively low (15% in 1907). However, as the century progressed and fewer people died from infectious diseases, this proportion increased markedly, peaking at 56% in 1968, before steadily declining.

Even when the effect of age is allowed for, the pattern of rising then falling death rates from cardiovascular disease remains. The age-standardised death rate for men increased from 376 to 843 per 100,000 persons between 1907 and 1968, before falling to 256 per 100,000 persons at the close of the 20th century (graph 9.15). For women, the rate increased from 328 to 583 per 100,000 persons between 1907 and 1952, then fell to 173 in 2000.

Graph - 9.15 Death rates(a) for cardiovascular disease

Cardiovascular disease

Cardiovascular disease, or disease of the circulatory system, comprises all diseases and conditions involving the heart and blood vessels including ischaemic heart disease, cerebrovascular disease (stroke), peripheral vascular disease and heart failure. In Australia, these diseases mostly result from impeded or diminished supply of blood to the heart, brain or leg muscles (d'Espaignet 1993).
All causes of death are classified according to the International Classification of Diseases (ICD). There have been a number of revisions of the ICD since it first came into effect in 1898. The most recent revision (ICD-10) was introduced in 1999. The chapter on circulatory disease comprises the following:

acute rheumatic fever and chronic rheumatic heart diseases (I00-I09)

hypertensive diseases (I10-I15)

ischaemic heart diseases (I20-I25)

pulmonary heart disease and diseases of pulmonary circulation (I26-I28)

other forms of heart disease (I30-I52)

cerebrovascular diseases (I60-I69)

diseases of arteries, arterioles and capillaries (I70-I79)

diseases of veins, lymphatic vessels and lymph nodes, not elsewhere classified (I80-I89)

other and unspecified diseases of the circulatory system (I95-99).

Standardised death rates enable the comparison of death rates between populations with differing age structures by relating them to a standard population. Death rates in this article have been standardised to the 1991 total population, and are expressed per 100,000 of the population.

Trends in death rates

There were three main changes in the pattern of deaths from cardiovascular disease between the beginning and end of the 20th century (see graphs 9.16 and 9.17):

Cardiovascular death rates are notably lower than they were at the beginning of the 20th century for all age groups except the very oldest (80 years and over).

The decline in cardiovascular death rates across the 20th century was greater for younger than for older age groups. For example, in 1907 the death rate for both males and females aged 0-24 years from cardiovascular diseases was more than 17 times larger than in 2000.

The age-specific death rates were substantially higher for males than for females in almost all age groups in 2000. In particular, the death rates for men aged 35-69 years were around two to three times the rates for women in those ages. There was no such systematic pattern in 1907.

Graph - 9.16 Age-specific death rates(a) for cardiovascular disease, Age groups 0-54 years

Graph - 9.16 Age-specific death rates(a) for cardiovascular disease, Age groups 50 years and over

Indigenous death rates

There is a lack of national health-related data on Aboriginal and Torres Strait Islander peoples. Based on the most reliable state and territory data (from Western Australia, South Australia and the Northern Territory), in 1996-98, Indigenous Australians died from cardiovascular disease at twice the rate of other Australians (AIHW 2001). In 2000 it was the leading cause of death among Indigenous persons (28% of Indigenous deaths). In 1998-2000, the median age at death from cardiovascular disease for Indigenous males was 57 years compared with 78 years for the non-Indigenous male population. For females, the median age for deaths from this cause was 64 years for Indigenous females and 84 years for the non-Indigenous female population. As well as from cardiovascular disease, Indigenous people have low median ages at death from all causes of death combined, and this is reflected in the lower life expectancy of Indigenous peoples.

The higher death rate from cardiovascular disease for the Indigenous population is consistent with a number of risk factors being more common among Indigenous peoples than the total population. In 1995 Indigenous Australians were about twice as likely to smoke. Indigenous adults were also about twice as likely to consume alcohol to a high risk level, despite a lower proportion of Indigenous adults consuming alcohol, compared to non-Indigenous adults (ABS 2001). In 1994, 25% of Indigenous males aged 18 years and over and 29% of Indigenous females aged 18 years and over were obese, compared to about 19% of all Australians aged 19 years and over in 1995 (ABS 2001).

Leading causes of cardiovascular deaths

The two leading categories of causes of death from cardiovascular disease are ischaemic heart diseases (also called coronary heart disease) and cerebrovascular disease (stroke). Table 9.18 presents cardiovascular deaths data for selected years over the last century. Over the last three decades, ischaemic heart diseases have been the leading cause of cardiovascular death for men and women. In 2000, they accounted for 59% of men's deaths and 48% of women's deaths from cardiovascular disease. This was despite a rapid decline in death rates from ischaemic heart diseases over the last three decades. Between 1968 and 2000, the death rate for ischaemic heart diseases fell from 498 to 150 deaths per 100,000 for men, and from 250 to 84 deaths per 100,000 for women.

Stroke has been the second most common cause of cardiovascular death since 1968, accounting for 21% of men's and 28% of women's deaths from cardiovascular disease in 2000. Throughout most of the 20th century, women were more likely to die from stroke than men. This pattern was reversed by 1968. Between 1968 and 2000, the standardised male death rate from stroke fell from 184 to 54 deaths per 100,000 population, while the female rate fell from 168 to 48. This represents a fall of 71% for both men and women over the period.

9.18 DEATH RATES(a) FOR SELECTED TYPES OF CARDIOVASCULAR DISEASE
	1907	1931(b)	1950(b)	1968(b)	2000
Cause of death (ICD-9) codes	rate	rate	rate	rate	rate

MALES

Ischaemic heart diseases (410-414)	n.a.	n.a.	n.a.	497.5	150.2
Cerebrovascular diseases (430-438)	107.1	106.3	144.3	183.5	53.5
Hypertension (401-405)	n.a.	n.a.	59.1	20.2	4.9
Chronic rheumatic heart diseases (393-398)	n.a.	59.8	9.6	9.7	1.0
All circulatory diseases (390-459)	375.6	479.2	743.4	842.7	255.5

FEMALES

Ischaemic heart diseases (410-414)	n.a.	n.a.	n.a.	249.5	84.0
Cerebrovascular diseases (430-438)	109.2	117.1	166.1	168.4	48.3
Hypertension (401-405)	n.a.	n.a.	53.5	20.6	5.0
Chronic rheumatic heart diseases (393-398)	n.a.	53.0	9.3	10.1	1.3
All circulatory diseases (390-459)	328.1	413.0	562.5	548.3	172.6

(a) Age-standardised rate per 100,000 persons. (b) 1931, 1950 and 1968 were years in which ICD revisions were implemented.
Source: AIHW Mortality Database.

Morbidity

While the death rate from cardiovascular disease has declined, its prevalence in the population has increased. According to results from three successive national health surveys, prevalence has risen from 8% (1.1 million) in 1977-78 to 17% (2.2 million) in 1989-90 and to 21% (2.8 million) in 1995 (ABS 1995). This could be partly associated with a broad range of improvements in medical interventions, which have increased the survival rate following acute cardiovascular events and among people living with cardiovascular disease. Improved techniques for diagnosing cardiovascular disease and better public information have increased the prevention and early detection of cardiovascular disease. The introduction of specialist ambulance services and better public knowledge of rescue-emergency management techniques have better enabled people affected by cardiovascular disease to receive rapid and effective treatment when required. Moreover, with the establishment of coronary care units and developments in surgery and drugs, the in-hospital care of patients has greatly improved.

The costs of cardiovascular disease are greater than for any other disease. In 1993-94, it accounted for $3.7b or 12% of total health costs (AIHW 2000c). In 1996, cardiovascular disease accounted for 22% of all disease burden in Australia (AIHW 1999). However, it should be recognised that the impact of cardiovascular disease is complex due to its association and co-morbidity with other conditions, particularly diabetes.

Risk factors

Studies have also attributed proportions of the total burden of disease to a range of health-related risk factors. The leading risk factors in 1996 (in terms of their contribution towards total disease burden) were tobacco smoking (10%), physical inactivity (7%), high blood pressure (5%), obesity (4%) and a lack of fruit and vegetables (3%) (AIHW 1999). All of these influence the prevalence of cardiovascular disease in particular. Smoking, physical inactivity and poor nutrition are risk factors that are associated with lifestyle choices, and these can increase the likelihood of, for example, high blood pressure, high cholesterol and obesity for an individual.

In 1998, it was estimated that 13% of all cardiovascular deaths were attributable to tobacco smoking (AIHW 2001). There has been only a slight decline in smoking rates in recent years. While 26% of Australians over 14 years old reported smoking in 1998 compared to 27% in 1995, there has been a steady trend in reduction of smoking rates since the 1970s, when smoking levels in the Australian population were around 37%.

In 1999, it was estimated that 44% of Australians aged 18-75 years (5.8 million people) did not undertake physical activity at the level recommended to obtain a health benefit. Between 1997 and 1999 there was a significant decline in the number of people reaching sufficient levels of physical exercise (from 62% to 56%) (AIHW 2001).

Good nutrition is the outcome of a complex range of dietary habits, including eating significant quantities of fruit and vegetables, and reducing intakes of saturated fat and salt. Among Australian adults, the consumption of saturated fat as a proportion of total energy intake has fallen over the past decade, and overall consumption of fats and of red meat (a source of saturated fat and dietary cholesterol) has been declining since the late 1960s. In contrast, consumption of fruit and vegetables has increased (ABS 2000).

In 1999-2000 it was estimated that almost three million Australian adults (aged 25 years and over) had high blood pressure, or were on treatment for the condition. More than six million Australian adults had high cholesterol levels (AIHW 2001). There has been a significant decline in the proportion of people with high blood pressure (and/or receiving treatment) since the 1980s, yet there is thought to have been little change in blood cholesterol levels in the Australian population since the 1980s. This is despite the apparent trend in declining intake of saturated fats and dietary cholesterol (AIHW 2001). In the last 20 years there has also been a significant increase in the proportions of overweight and obese Australians. Of those people living in capital cities, the proportion of overweight or obese women aged 25-64 years has increased from 27% in 1980 to 45% in 1999-2000. For men the proportion increased from 48% to 65% (AIHW 2001).

Overall trends in the prevalence of risk factors

Public health promotion programs have encouraged Australians to improve their health and reduce their risk factors. One of the results of the public response is that there have been several trends in the reduction of behavioural risk factors directly associated with cardiovascular disease over the last 30 years. This includes the reduction in smoking rates, reduction in saturated fat intake and increase in fruit and vegetable consumption. This has coincided with an overall reduction in cardiovascular death rates over this period. However, the increased prevalence of overweight and obese Australians seems likely to be related to the increase in physical inactivity. As overweight and obesity are also related to diabetes, high cholesterol and high blood pressure, a continuing increase in the prevalence of these conditions/risk factors within the Australian population is likely to influence the prevalence of cardiovascular disease.

References

AIHW (Australian Institute of Health and Welfare) 1999, The burden of disease and injury in Australia, AIHW Cat. No. PHE17, AIHW, Canberra.

AIHW 2000a, Australia's Health 2000, AIHW Cat. No. 19, AIHW, Canberra.

AIHW 2000b, Australian long term trends in mortality, AIHW, Canberra.

AIHW 2000c, First Report on National Health Priority Areas 1996, AIHW Cat. No. PHE1, AIHW, Canberra.

AIHW 2001, Heart, Stroke and Vascular Diseases: Australian Facts 2001, AIHW Cat. No. CVD14, AIHW, Canberra.

ABS (Australian Bureau of Statistics) 1979, Australian Health Survey, 1977-78: Chronic Conditions, cat. no. 4314.0, ABS, Canberra.

ABS 1995, National Health Survey: Cardiovascular and Related Conditions, Australia, cat. no. 4372.0, ABS, Canberra.

ABS 2000, Apparent Consumption of Foodstuffs, Australia, 1997-98 and 1998-99, cat. no. 4306.0, ABS, Canberra.

ABS 2001, The Health and Welfare of Australia's Aboriginal and Torres Strait Islander Peoples, cat. no. 4704.0, ABS, Canberra.

d'Espaignet ET 1993, Trends in Australian Mortality - Diseases of the Circulatory System: 1950-1991, Australian Government Publishing Service, Canberra.