Past, Present and Future of Cardiovascular Disease in Australia

This paper used official mortality data for Australia; data on incidence of coronary events and levels of risk factors from the World Health Organization's MONICA Project (to MONItor trends and determinants of CArdiovascular disease) in Newcastle, New South Wales, Australia; and national data on coronary procedures and medications to show the past trends and present situation of cardiovascular disease (CVD) in Australia. There are well-established trends of declining rates of deaths from all causes, CVD, coronary heart disease and stroke and of non- fatal coronary events (which are also becoming less severe). The three major risk factors of cigarette smoking, high blood pressure and high blood cholesterol have also been declining for some time. Despite this picture, which is encouraging from a population perspective, the medical costs of CVD are rising. This is due to increases in medical and surgical procedures and the use of increasingly expensive drugs. The challenge for public health is to keep the focus on prevention, including attention to the increasing prevalence of overweight and obesity. J Epidemiol, 1996 ; 6 : S209-S213.


Past, Present
and Future of Cardiovascular Disease in Australia Annette J. Dobson This paper used official mortality data for Australia; data on incidence of coronary events and levels of risk factors from the World Health Organization's MONICA Project (to MONItor trends and determinants of CArdiovascular disease) in Newcastle, New South Wales, Australia; and national data on coronary procedures and medications to show the past trends and present situation of cardiovascular disease (CVD) in Australia. There are well-established trends of declining rates of deaths from all causes, CVD, coronary heart disease and stroke and of nonfatal coronary events (which are also becoming less severe). The three major risk factors of cigarette smoking, high blood pressure and high blood cholesterol have also been declining for some time. Despite this picture, which is encouraging from a population perspective, the medical costs of CVD are rising. This is due to increases in medical and surgical procedures and the use of increasingly expensive drugs. The challenge for public health is to keep the focus on prevention, including attention to the increasing prevalence of overweight and obesity. J Epidemiol,1996 ; 6 : S209-S213.
WHO MONICA Project, trends, cardiovascular disease, Australia The purpose of this paper is to review past trends and the present situation of cardiovascular disease (CVD) in Australia and to predict future patterns of disease, risk factor levels and costs.

MATERIALS AND METHODS
Data on mortality are produced annually by the Australian Bureau of Statistics based on death certificates. They include demographic information and the primary cause of death, coded according to the 9th revision of the International Classification of Diseases (ICD-9) or earlier revisions. Numbers of deaths from specific causes are tabulated by sex and 5-year age group by the National Heart Foundation of Australia and these, together with the corresponding population estimates for each year, were used to calculate mortality rates. The causes of death considered here are: all causes; all CVD (ICD-9 codes 390-459) ; ischaemic or coronary heart disease (CHD) (ICD-9 codes 410-414) ; and cerebrovascular disease or stroke (ICD-9 codes 430-438). For this paper directly age-standardized rates were calculated using the World Standard Population weights for 5-year age groups for 35-69 years1).
To illustrate trends in fatal and non-fatal coronary events, data from the World Health Organization's MONICA Project (to MONItor trends and determinants of CArdiovascular disease) were used. These data were collected in the Newcastle area (Hunter Region) of New South Wales, Australia during 1985-1993 for all people aged under 70 years in a geographically defined population. Event registration was conducted by continuous monitoring of all suspected heart attacks or coronary deaths through hospital admissions and death registrations. This paper includes all events classified as i) fatal cases meeting the criteria for definite acute myocardial infarction (MI), possible MI or unclassifiable coronary deathswhether hospitalised or not2); ii) non-fatal definite MI 2); iii) non-fatal probable MI -cases with typical symptoms and electrocardiogram or enzyme changes suggesting cardiac ischaemic but not severe enough to fulfil the criteria for nonfatal definite MI 3) ; iv) prolonged chest pain -cases meeting the MONICA criteria for non-fatal possible MI but not the criteria for non-fatal probable MI; these are mainly cases of stable or unstable angina 2,3).
Details of the study methods have been published previously 4). For non-fatal events, almost all patients were hospitalized. Annual event rates were calculated using direct standardization with the World Standard Population weights for 5-year age groups for 35 -69 years 1) and are presented on a logarithmic scale.
Trends in risk factors are also illustrated by data from the Newcastle collaborating centre of the WHO MONICA Project. Risk factor surveys were conducted in the study population in 1983, 1988-9 and 1994. The standardized protocol for the Project was used 5) and the survey methods have been described previously 6). For this paper data are shown on prevalence of regular cigarette smoking (%) and mean levels of diastolic blood pressure (mmHg) , total cholesterol (mmol/L) and body mass index (kg/m2). The risk factor data refer to the age group 35-64 years and are directly age-standardized using the World Standard Population weights for 5 year age groups 1).
Data on numbers of coronary procedures in Australia are collected by the National Heart Foundation from all the specialist units providing the services. As the data are not disaggregated by age or sex they are presented here as crude rates calculated by dividing the numbers of procedures by the national population aged 35 -74 years for the same calendar year. For coronary artery bypass graft (CABG) operations data are presented for 1970-1994 and for coronary angioplasty for 1980 -1993; before these times very few of these procedures were performed.
Recent changes in the use of pharmaceuticals are illustrated by data for 1990/1-1994. These were obtained through the Australian Institute of Health and Welfare from the Drug Utilization Sub-Committee data base of the Commonwealth Department of Health and Family Services. They are estimates obtained by combining data on prescription counts from the Pharmacy Guild survey and prescriptions submitted for payment of a subsidy through the Health Insurance Commission 7). The data are presented in terms of defined daily dose per 1,000 population per day.

RESULTS
Death rates from stroke in Australia have been falling fol over 30 years (Figure 1). Death rates from CHD increased during the 1950's and early 1960's, peaked around 1966 and since then have declined. As a result the fall in death rates for men aged 35 -69 years between 1966 and 1994 was 49% for at causes and 71% for CHD. The corresponding falls in death rates for women were 48% for all causes and 74% for CHD. A consequence of these changes in mortality from the major categories of cardiovascular diseases is that in the last 25 years life expectancy has increased by 7 years for both men and women.
Data on rates of CHD in the Newcastle area show a pattern of decreasing severity (Figure 2). During 1985-1993 death rates fell for men and women, in line with the national trends. Rates of non-fatal definite MI also fell but more slowly than death rates, especially for women. In contrast for milder disease, rates of non-fatal probable MI initially increased and then slightly declined while rates of hospitalization for episodes of prolonged chest pain increased.
The long-term declines in death rates and severity of CHD are consistent with changes in the major risk factors. Data from the Newcastle area illustrate the main trends ( Figure 3). Prevalence of cigarette smoking declined from 36% to 23% among men between 1983 and 1994. For women the decline was smaller, from 24% to 21%. Blood pressure levels and prevalence of hypertension also declined; over the study period mean diastolic blood pressure fell by 2.5mmHg for men and 3mmHg for women. These data from the WHO MONICA Project also show reductions in mean levels of total cholesterol of 0.2 -0.3mmol/L. Despite these improvements, a potential future problem is the increase in mean body mass index (BMI) and prevalence of overweight and obesity.
Medical treatment of coronary disease is increasing substantially in Australia. Figure 4 shows the national rates for coronary artery bypass grafts and angioplasty. Pharmaceutical treatment has also increased, especially the use of more expensive drugs. Figure 5 gives national data showing marked increases in angiotensin converting enzyme (ACE) inhibitors and differing trends for other antihypertensives. Figure 6 shows the corresponding trends for lipid lowering drugs. Drugs for CVD, including antihypertensives, calcium channel blockers, beta blockers, diuretics and lipid lowering drugs, now make up 27% of the total costs of government subsidized drugs used in the community. In particular, the anti-hyperlipidaemic agent Simvastatin was the drug which cost the government the most in 1994 -$95 million.

DISCUSSION
In summary, there are two important aspects of the CVD epidemic in Australia at present.
On one hand the disease has been diminishing for more than 25 years. Over a long period cigarette smoking has been declining 8). There have also been substantial dietary changes, with lower consumption of meat and dairy products and increases in fruit and vegetables 9,10). Biological risk factors such as blood pressure and cholesterol levels have declined 11,12) In line with these improvements in risk levels, first death rates and then rates of major, non-fatal coronary events declined.  The increase in less severe events is also consistent with the risk factor changes being important determinants of the decrease in disease. As the favourable trends in risk factors are well-established and show no signs of slowing down, it seems reasonable to expect that disease rates and severity will decline for some years, at least. The only worrying factor is the increase in body weight.
On the other hand, against this background of declining disease, there are substantial increases in medical and surgical investigations and procedures related to CVD and increasing use of pharmaceuticals, especially newer, much more expensive drugs. These changes in medical care have occurred after the reductions in CVD were already underway. They are directed at the minority of the population with identifiable disease. While part of the more recent improvement in mortality and morbidity rates probably is attributable to medical interventions, the costs are great. Cardiovascular medicine accounts a growing proportion of the health care budget. This epitomises the high risk strategy which Rose described as "no more than an expensive rescue operation, offering disappointingly little towards solving the overall problem " 13).
The population approach to prevention offers greater potential benefits at less cost. The continuing targets are reductions in cigarette smoking, improvements in diet and increases in physical activity. To these is now added a new target -to combat overweight and obesity. An additional challenge for public health is to maintain the focus on primary prevention for everyone, against a background of a rising wave of medical interventions and costs for those people with established disease.