3303.0.55.003 - Changing Patterns of Mortality in Australia, 1968-2017 Quality Declaration 
Latest ISSUE Released at 11:30 AM (CANBERRA TIME) 30/11/2018  First Issue
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CHANGING PATTERNS OF MORTALITY IN AUSTRALIA

The release of the 2017 Causes of Death report marked half a century since 1968, the year that the heart disease epidemic in Australia reached its peak. In 1968, Ischaemic heart disease (IHD) accounted for almost one third of all deaths and half of those deaths were among people under 70 years of age.

After 1968 the death rate from IHD began to decline. Studies undertaken in response to the rapidly increasing mortality rates in the 1940s and 1950s began to highlight key risk factors and the earliest of interventions began to slow and reverse decades of increasing cardiovascular death rates.

Reductions in mortality over the past 50 years have seen life expectancy at birth increase by more than 10 years (increasing from 67.6 to 80.5 years for males, and from 74.2 to 84.6 years for females, when comparing 1965-67 with 2015-17 (ABS, 2014; ABS, 2018)). Over this period our understanding of diseases and ability to prevent and treat them has steadily grown.

This report examines changes in death rates over the past 50 years, focussing on cardiovascular diseases. It also provides information on advancements in understanding and treatment of cardiovascular diseases which have contributed to reductions in mortality and corresponding increases in life expectancy. Other key changes in patterns of mortality will be covered in subsequent releases.

CHANGES IN LEADING CAUSES OF DEATH

One of the simplest and most commonly used measures of mortality is the leading cause of death tabulation. The ABS bases leading cause tabulations on the Bulletin of the World Health Organization, Volume 84, Number 4, April 2006, 297-304. While there have been classification changes since 1968, correspondences have been used to construct a tabulation of leading causes for 1968 based on the same groups of conditions used in the present day. This is shown in the table below.


Top 10 leading causes of death, 1968, and corresponding 2017 data (a)(b)(c)(d)(e)(f)(g)

Leading causes of death
Rank

1968

Rank

2017

Deaths (no.)

1968

Deaths (no.)

2017

Deaths (%)

1968

Deaths (%)

2017


Ischaemic heart diseases
1
1
33 411
18 590
30.5
11.6
Cerebrovascular diseases
2
3
15 363
10 186
14.0
6.3
Chronic lower respiratory diseases
3
4
3 706
8 357
3.4
5.2
Land transport accidents
4
28
3 609
1 318
3.3
0.8
Influenza and pneumonia
5
9
3 275
4 269
3.0
2.7
Malignant neoplasm of trachea, bronchus and lung
6
5
2 893
8 262
2.6
5.1
Atherosclerosis
7
57
2 574
81
2.3
0.1
Malignant neoplasm of colon, sigmoid, rectum and anus
8
6
2 533
5 325
2.3
3.3
Certain conditions originating in the perinatal period
9
42
2 358
582
2.2
0.4
Diabetes
10
7
1 955
4 839
1.8
3.0

Footnotes:
(a) Causes listed are based on the World Health Organization's recommended tabulation of leading causes, created on codes for Version 10 of the International Classification of Disease (ICD-10). For a correspondence of ICD-10 causes to ICD-8, see 'Correspondence of selected causes of death between versions of the International Classification of Diseases' (Appendix) in this publication. See Explanatory Notes 36-39 in Causes of Death, Australia, 2017 (cat. no. 3303.0) for further information on leading causes.
(b) Groupings of deaths coded to Symptoms, signs and ill-defined conditions (780-796 in ICD-8 and R00-R99 in ICD-10) are not included in analysis, due to the unspecific nature of these causes. Furthermore, many deaths coded to this chapter are likely to be affected by revisions (which applies to data for 2006 onwards), and hence re-coded to more specific causes of death as they progress through the revisions process.
(c) In this publication, the ABS includes C26.0 (malignant neoplasm of the intestinal tract, part unspecified) in the WHO leading cause grouping for Malignant neoplasm of colon, sigmoid, rectum and anus (now C18-C21, C26.0) for ICD-10 data (1998-2017). This differs to the suggested WHO tabulation of leading causes for these cancers. For further details on the reasoning behind the inclusion of C26.0 in this leading cause grouping, see Complexities in the measurement of bowel cancer in Australia, in Causes of Death, Australia, 2015 (cat. no. 3303.0). As the certification trend which has led to the inclusion of C26.0 in the leading cause grouping does not apply to earlier cause of death data, the corresponding ICD-8 code has not been included in the leading cause grouping.
(d) The ABS now includes Y87.0 (Sequelae of intentional self-harm), Y87.1 (Sequelae of assault) and Y85 (Sequelae transport accidents) in the WHO leading cause grouping for Intentional self-harm (now X60-X84, Y87.0), Assault (now X85-Y09, Y87.1) and Land transport Accidents (V01-V89, Y85). This differs to the suggested WHO tabulation of leading causes, but has been applied to harmonise data between the WHO leading cause grouping and subject-specific data cubes for intentional self-harm, assault and transport accidents which is published as part of the ABS Causes of Death collection (cat. no. 3303.0). The corresponding sequelae codes have also been included in the relevant cause groupings for ICD-8 data (E959, Late effect of self-inflicted injury; E969, Late effect of injury purposefully inflicted by other person and; E940, Late effect of motor vehicle accident). See Correspondence of Selected Causes of Death Between Versions of the International Classification of Diseases (Appendix) for the leading cause correspondence.
(e) Deaths where the underlying cause of death was coded to the 'heart failure and ill-defined heart disease' leading cause grouping have been excluded from the above tabulation. Heart failure is a common outcome of long-term ischaemic heart disease, and when coded as the underlying cause of death is likely due to gaps in medical information at the time of certification of death. There were 4,336 deaths assigned as due to heart failure in 1968 and 3,487 deaths in 2017.
(f) Caution should be used in comparing leading cause rankings between 1968 and 2017. Three more leading causes exist for 2017 data than for 1968 data. This is due to the inability to adequately correspond HIV and respiratory failure to ICD-8, and due the exclusion of Heart failure and complications and ill-defined heart disease in ICD-8 (see above).
(g) The International Classification of Diseases (ICD) undergoes periodic revisions by the World Health Organization to reflect changes in medical terminology, medical knowledge and death certification. Although large disease groups can be mapped between different versions of the ICD there may be slight differences in disease groupings between versions. ICD-8, ICD-9 and ICD-10 codes are included in this publication.



The leading causes of death in 1968 were characterised by high numbers of IHD and cerebrovascular disease deaths. In 1968 these conditions accounted for nearly 49,000 deaths and 44.5% of all deaths. In 2017 these conditions accounted for only 17.9% of all deaths. IHD accounted for almost 10 times the number of deaths as the 3rd ranked condition (Chronic lower respiratory diseases), highlighting an order of magnitude difference between deaths from IHD and other common causes of death.

Aside from IHD and stroke, two other key differences in leading causes between 1968 and 2017 were the ranking of Land transport accidents (4th in 1968 compared with 28th in 2017) and Certain conditions originating in the perinatal period (9th in 1968 compared with 42nd in 2017). These changes highlight the long term and cumulative effects of progressive road safety policies and mechanical/manufacturing advancements, as well as the wide ranging educational, medical and scientific advances which have reduced perinatal mortality rates.

The below table shows the leading causes ranked according to their order in 2017. Seven of the top ten leading causes remain the same conditions as those in 1968, but despite this, differences are quite profound.


Top 10 leading causes of death, 2017, and corresponding 1968 data (a)(b)(c)(d)(e)(f)

Leading causes of death
Rank

2017

Rank

1968

Deaths (no.)

2017

Deaths (no.)

1968

Deaths (%)

2017

Deaths (%)

1968


Ischaemic heart diseases
1
1
18 590
33 411
11.6
30.5
Dementia, including Alzheimer disease
2
40
13 729
198
8.5
0.2
Cerebrovascular diseases
3
2
10 186
15 363
6.3
14.0
Chronic lower respiratory diseases
4
3
8 357
3 706
5.2
3.4
Malignant neoplasm of trachea, bronchus and lung
5
6
8 262
2 893
5.1
2.6
Malignant neoplasm of colon, sigmoid, rectum and anus
6
8
5 325
2 533
3.3
2.3
Diabetes
7
10
4 839
1 955
3.0
1.8
Malignant neoplasms of lymphoid, haematopoietic and related tissue
8
14
4 499
1 621
2.8
1.5
Influenza and pneumonia
9
5
4 269
3 275
2.7
3.0
Diseases of the urinary system
10
11
3 565
1 929
2.2
1.8

Footnotes:
(a) Causes listed are based on the World Health Organization's recommended tabulation of leading causes, created on codes for Version 10 of the International Classification of Disease (ICD-10). For a correspondence of ICD-10 causes to ICD-8, see 'Correspondence of selected causes of death between versions of the International Classification of Diseases' (Appendix) in this publication. See Explanatory Notes 36-39 in Causes of Death, Australia, 2017 (cat. no. 3303.0) for further information on leading causes.
(b) Groupings of deaths coded to Symptoms, signs and ill-defined conditions (780-796 in ICD-8 and R00-R99 in ICD-10) are not included in analysis, due to the unspecific nature of these causes. Furthermore, many deaths coded to this chapter are likely to be affected by revisions (which applies to data for 2006 onwards), and hence re-coded to more specific causes of death as they progress through the revisions process.
(c) In this publication, the ABS includes C26.0 (malignant neoplasm of the intestinal tract, part unspecified) in the WHO leading cause grouping for Malignant neoplasm of colon, sigmoid, rectum and anus (now C18-C21, C26.0) for ICD-10 data (1998-2017). This differs to the suggested WHO tabulation of leading causes for these cancers. For further details on the reasoning behind the inclusion of C26.0 in this leading cause grouping, see Complexities in the measurement of bowel cancer in Australia, in Causes of Death, Australia, 2015 (cat. no. 3303.0). As the certification trend which has led to the inclusion of C26.0 in the leading cause grouping does not apply to earlier cause of death data, the corresponding ICD-8 code has not been included in the leading cause grouping.
(d) Deaths where the underlying cause of death was coded to the 'heart failure and ill-defined heart disease' leading cause grouping have been excluded from the above tabulation. Heart failure is a common outcome of long-term ischaemic heart disease, and when coded as the underlying cause of death is likely due to gaps in medical information at the time of certification of death. There were 4,336 deaths assigned as due to heart failure in 1968 and 3,487 deaths in 2017.
(e) Caution should be used in comparing leading cause rankings between 1968 and 2017. Three more leading causes exist for 2017 data than for 1968 data. This is due to the inability to adequately correspond HIV and respiratory failure to ICD-8, and due the exclusion of Heart failure and complications and ill-defined heart disease in ICD-8 (see above).
(f) The International Classification of Diseases (ICD) undergoes periodic revisions by the World Health Organization to reflect changes in medical terminology, medical knowledge and death certification. Although large disease groups can be mapped between different versions of the ICD there may be slight differences in disease groupings between versions. ICD-8, ICD-9 and ICD-10 codes are included in this publication.


In 2017, the decreased number and proportional contributions of IHD and stroke compared to 1968 are significant. However, as the remainder of this report will highlight, they provide only a small indication of the magnitude of change over time.

Another key difference between mortality in 2017 and 1968 is the emergence of Dementia, including Alzheimer disease, now the second leading cause. While increased life expectancy is the main reason for this increase, there are also death certification changes and classification changes which have contributed to the emergence of dementia as a leading cause.

Other changes in leading causes include the increased rank of Diabetes (7th in 2017 compared with 10th in 1968) and Malignant neoplasms of lymphoid, haematopoietic and related tissue (ranked 8th in 2017 compared with 14th in 1968).

While leading cause rankings give some indication of changes in patterns of mortality, other measures, such as standardised death rates, age-specific death rates, and years of potential life lost (as a measure of premature mortality), provide a more in-depth view of how changes have occurred across different population cohorts. The initial analysis in this report focuses on these measures for cardiovascular diseases, with other key changes in patterns of mortality to be covered in subsequent releases.

The graph below presents standardised death rates for the top 5 leading causes in 1968 alongside rates for 2017. It provides a further insight into the magnitude of the decrease in death rates for IHD and strokes by taking account of the change in the population size and structure over the 50-year period.

Graph Image for Standardised death rates for top 5 leading causes in 1968, compared with 2017

Footnote(s): (a) Causes of death data for 2017 are preliminary and subject to a revisions process. See Explanatory Notes 57-60 in Causes of Death, Australia, 2017, and A More Timely Annual Collection: Changes to ABS Processes (Technical Note) Causes of Death, Australia, 2015 (cat. no. 3303.0). (b) Causes listed are based on the World Health Organization's recommended tabulation of leading causes, created on codes for Version 10 of the International Classification of Disease (ICD-10). For a correspondence of ICD-10 causes to ICD-8, see 'Correspondence of selected causes of death between versions of the International Classification of Diseases' (Appendix) in this publication. See Explanatory Notes 36-39 in Causes of Death, Australia, 2017 (cat. no. 3303.0) for further information on leading causes. (c) The ABS now includes Y85 (Sequelae transport accidents) in the WHO leading cause grouping for Land transport accidents (V01-V89, Y85). This differs to the suggested WHO tabulation of leading causes, but has been applied to harmonise data between the WHO leading cause grouping and subject-specific data for land transport accidents which is published as part of the ABS Causes of Death collection (cat. no. 3303.0). The corresponding sequelae codes have also been included in the relevant cause groupings for ICD-8 data (E940, Late effect of motor vehicle accident). (d) Deaths where the underlying cause of death was coded to the 'heart failure and ill-defined heart disease' leading cause grouping have been excluded from this graph. Heart failure is a common outcome of long-term ischaemic heart disease, and when coded as the underlying cause of death is likely due to gaps in medical information at the time of certification of death. There were 4,336 deaths assigned as due to heart failure in 1968 and 3,487 deaths in 2017. (e) Age-standardised death rates (SDRs) enable the comparison of death rates between populations with different age structures. The SDRs in this graph are presented on a per 100,000 population basis, using the estimated mid-year population (30 June). See Explanatory Notes 44-47 and the Glossary in Causes of Death, Australia, 2017 (cat. no. 3303.0) for further information. (f) See the 'Population Estimates Used in Calculating Rates, 1968 to 2017' data cube in this publication for information on the population estimates used in calculating rates. (g) The International Classification of Diseases (ICD) undergoes periodic revisions by the World Health Organization to reflect changes in medical terminology, medical knowledge and death certification. Although large disease groups can be mapped between different versions of the ICD there may be slight differences in disease groupings between versions. ICD-8, ICD-9 and ICD-10 codes are included in this publication.

Source(s): Standardised death rates for top 5 leading causes in 1968, compared with 2017-Standardised death rates for top 5 leading causes in 1968, compared with 2017



While the magnitude of changes in cardiovascular disease mortality are the focus of this report, these changes do not indicate that IHD is less of a concern for individuals now than it was in 1968. Cardiovascular health is critically important for individuals, and while medical advances may have helped reduce mortality rates, especially among younger people, the maintenance of cardiovascular health can have a huge impact on both length and quality of life.

The Heart Foundation website (https://www.heartfoundation.org.au/) provides a wealth of information and resources about cardiovascular diseases in Australia.


Acknowledgements

The ABS would like to thank Dr Tony Ireland for his co-authorship of this report. His medical knowledge, historical insights and advice have been invaluable in this project.

The ABS would also like to thank Professor Annette Dobson for her work in reviewing and advising on elements of this report.


References

ABS (Australian Bureau of Statistics) 2014, Australian Historical Population Statistics, 2014, cat. no. 3105.0.65.001, ABS, Canberra.

ABS (Australian Bureau of Statistics) 2018, Life Tables, States, Territories and Australia, 2015-2017, cat. no. 3302.0.55.001, ABS, Canberra.