The decline in coronary heart disease mortality is slowing in young adults (Australia 1976–2006): A time trend analysis

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Abstract

Background

To examine whether the recent flattening of mortality rates for coronary heart disease (CHD) observed among young adults in the UK and the US is also occurring in the Australian population.

Methods

Mortality data from 1976 to 2006 were used to calculate overall age-adjusted and age-specific mortality rates for Australian adults aged ≥ 25 years. Joinpoint regression was fitted to estimate the annual change and detect points in time where significant changes in the trends occur.

Results

Between 1976 and 2006 age-adjusted CHD mortality rates declined by 73% in men and 70% in women. A steady decline continued in older groups. Beginning in 1991, a slowing of the fall in mortality rates was observed in younger men, and CHD mortality rates were essentially flat in men 25–34 years. Among men aged 35–44, a reduction of the decline in CHD mortality was observed from 1992, and likewise in men aged 45–54 years from 1994. Very similar patterns were observed in women with significant slowdowns starting in 1980, 1988 and 1991 for those aged 25–34 years, 35–44 years and 45–54 years respectively.

Conclusions

In Australian men and women aged 25–54 years, the CHD mortality decline has slowed since the early 1990s. The most likely explanations for reduction of the CHD mortality decline are attenuations or reversal of the earlier declines in major traditional risk factors (tobacco smoking, serum cholesterol, blood pressure) and diabetes mellitus.

Introduction

In the last four decades, coronary heart disease mortality has been continuously decreasing in many countries [1], with approximately 2/3 of the decline attributable to changes in risk factors and 1/3 to evidence based treatments [2], [3], [4], [5], [6]. In Australia and New Zealand, even more of the decline, around 80% has been attributable to changes in risk factors [7], [8].

Nevertheless, because of population ageing, coronary heart disease will continue to exert a heavy burden for both developed and developing countries [9], [10].

Furthermore, there is increasing evidence that these hard won gains could now be in jeopardy. A slowing of the decline in coronary heart disease mortality is now occurring in young adults in the US and in the UK. These changes almost certainly reflect attenuation of declines, arrest or reversal of trends in major risk factors, since dramatic deterioration of medical care in this age group appears unlikely [11], [12], [13].

In Australia, age-adjusted coronary heart disease mortality rates have also been declining over the last three decades. However, there is some evidence that the rate of decline for the most recent birth cohorts (aged 25–40 years in 1992) slowed or even ceased around the 1990s [14].

Our aim is therefore to examine more recent age and gender specific trends in CHD mortality between 1976 and 2006.

Section snippets

Methods

Vital statistics data including population numbers were obtained from the General Record of Incidence of Mortality (Australian Institute of Health and Welfare) for the period 1976 to 2006[15]. The underlying cause of death from coronary heart disease was determined using the International Classification of Diseases (ICD) 8 and 9 codes 410–414 for 1976–1996 and ICD-10 codes I20–I25 for 1996–2006. Age-adjustment was performed using the direct method to the estimated Australian population of the

Results

From 1976 to 2006, the overall age-adjusted mortality rate for coronary heart disease declined by 73% in men and 70% in women (Fig. 1). The average annual rate of decline over the entire period was 4.3% for men and 3.9% for women. The last ten years showed a slightly higher average annual rate of decline 5.8% for men and women.

The age-adjusted rates concealed striking differences in the age-specific rates (Fig. 2 and Table 1a, Table 1b). The decline in mortality continued for men and women

Discussion

The overall decline in age-adjusted CHD mortality rates in Australia since 1980 conceals an important change in younger adults. This recent slowing in the rate of mortality decline is occurring in both men and women aged below 45 years. This mortality flattening first occurred in the 1980s in the very youngest groups, and started later around 1991–1994 for those aged 45 to 54 years.

The attenuation in CHD mortality decline probably started in the early 1990s among male cohorts born between 1955

Funding

AP is a recipient of a VicHealth Fellowship and receives funds from NHMRC project grant 465130.

Ethical approval

Not required.

Competing interest

None declared.

Contributorship

MOF, SC, AP, RT, SA and CS conceived the idea of the manuscript. MOF procured the data. MOF and SC conducted the main analyses and drafted the manuscript. All authors contributed to the final manuscript. SC is the guarantor.

Acknowledgments

We wish to thanks the Australian Institute of Health and Welfare for kindly provide us with the updated General Record of Incidence of Mortality workbook.

The authors of this manuscript have certified that they comply with the Principles of Ethical Publishing in the International Journal of Cardiology [29].

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