Causes of Death, Australia methodology

This publication contains statistics on causes of death for Australia, together with selected statistics on perinatal deaths.

Statistics on perinatal deaths for the 2007-2009 reference years were published separately in Perinatal Deaths, Australia, 2009 (cat. no. 3304.0).

Information in Causes of Death, Australia is not comparable with deaths data published in the monthly Provisional Mortality Statistics reports which provides preliminary counts of doctor certified deaths by date of occurrence in 2020.

In order to complete a death registration, the death must be certified by either a doctor using the Medical Certificate of Cause of Death, or by a coroner. In 2020, 87.4% of deaths were certified by a doctor. The remaining 12.6% were certified by a coroner. There are variations between jurisdictions in relation to the proportion of deaths certified by a coroner, ranging from 7.5% of deaths certified by a coroner and registered in Queensland, to 26.5% of deaths certified by a coroner and registered in the Northern Territory.

In order to complete a perinatal death registration, the death must be certified by either a doctor, using the Medical Certificate of Cause of Perinatal Death, or by a coroner. In 2020, 97.7% of perinatal deaths were certified by a doctor, with the remaining 2.3% certified by a coroner.

It is the role of the coroner to investigate the circumstances surrounding all reportable deaths and to establish, wherever possible, the circumstances surrounding the death, and the cause(s) of death. Although there is variation across jurisdictions in what constitutes a death that is reportable to a coroner, they are generally reported in circumstances such as:

• where the person died unexpectedly and the cause of death is unknown
• where the person died in a violent or unnatural manner
• where the person died during, or as a result of an anaesthetic
• where the person was 'held in care' or in custody immediately before they died
• where the identity of the person who has died is unknown.

The registration of deaths is the responsibility of the eight individual state and territory Registries of Births, Deaths and Marriages. As part of the registration process, information about the cause of death is supplied by the medical practitioner certifying the death or by a coroner. Other information about the deceased is supplied by a relative or other person acquainted with the deceased, or by an official of the institution where the death occurred. The information is provided to the Australian Bureau of Statistics (ABS) by individual registries for coding and compilation into aggregate statistics. In addition, the ABS supplements this data with information from the National Coronial Information System (NCIS). The following diagram shows the process undertaken in producing causes of death statistics for Australia.

The diagram below outlines the Australian Causes of Death Statistics System. Each death is certified by either a doctor or coroner and the resultant information is provided to the Australian Bureau of Statistics (ABS) through the Registrar of Births, Deaths and Marriages in each state or territory. Information is also provided via the National Coronial Information System for those deaths certified by a coroner. The ABS processes, codes and validates this information, which is then provided in statistical outputs.

Ideally, for compiling annual time series, the number of deaths should be recorded and reported as those which occurred within a given reference period, such as a calendar year. However, there can be lags in the registration of deaths with the state or territory registries and so not all deaths are registered in the year that they occur. There may also be further delays to the ABS receiving notification of the death from the registries due to processing or data transfer lags. Therefore, every death record will have:

• a date on which the death occurred (the date of occurrence)
• a date on which the death is registered with the state and territory registry (date of registration); and
• a date on which the registered death is lodged with the ABS and deemed in scope.

With exception to the statistics published by Year of Occurrence (Data Cube 14), all deaths referred to in this publication relate to the number of deaths registered, not those which actually occurred, in the years shown.

The scope for each reference year of the death registrations includes:

• deaths registered in the reference year and received by the ABS in the reference year;
• deaths registered in the reference year and received by the ABS in the first quarter of the subsequent year; and
• deaths registered in the years prior to the reference year but not received by ABS until the reference year or the first quarter of the subsequent year, provided that these records have not been included in any statistics from earlier periods.

From 2007 onwards, data for a particular reference year includes all deaths registered in Australia for the reference year that are received by the ABS by the end of the March quarter of the subsequent year. Death records received by the ABS during the March quarter of 2021 which were initially registered in 2020 (but for which registration was not fully completed until 2021) were assigned to the 2020 reference year. Any registrations relating to 2020 which were received by the ABS from April 2021 will be assigned to the 2021 reference year. Approximately 5% to 8% of deaths occurring in one year are not registered until the following year or later. 

Prior to 2007, the scope for the reference year of the Death Registrations collection included:

• deaths registered in the reference year and received by the ABS in the reference year;
• deaths registered in the reference year and received by the ABS in the first quarter of the subsequent year; and
• deaths registered during the two years prior to the reference year but not received by the ABS until the reference year.

The ABS Causes of Death collection includes all deaths that occurred and were registered in Australia, including deaths of persons whose usual residence was overseas. Deaths of Australian residents that occurred outside Australia may be registered by individual registries, but are not included in ABS deaths or causes of death statistics.

The current scope of the statistics includes:

• all deaths being registered for the first time;
• deaths in Australia of temporary visitors to Australia;
• deaths occurring within Australian Territorial waters;
• deaths occurring in Australian Antarctic Territories or other external territories (including Norfolk Island);
• deaths occurring in transit (i.e. on ships or planes) if registered in the Australian state or territory of 'next port of call';
• deaths of Australian Nationals overseas who were employed at Australian legations and consular offices (i.e. deaths of Australian diplomats while overseas) where able to be identified; and
• deaths that occurred in earlier reference periods that have not been previously registered (late registrations).

The scope of the statistics excludes:

• repatriation of human remains where the death occurred overseas;
• deaths of foreign diplomatic staff in Australia (where these are able to be identified); 
• stillbirths/fetal deaths (these are included in perinatal death statistics (see Perinatal deaths, below)). In 2007-2009 these were published separately in Perinatal Deaths, Australia (cat. no. 3304.0) but are now included in this publication.

Deaths registered on Norfolk Island from 1 July 2016 are included in this publication. This is due to the introduction of the Norfolk Island Legislation Amendment Act 2015. Norfolk Island deaths are included in statistics for "Other Territories" as well as totals for all of Australia. Deaths registered on Norfolk Island prior to 1 July 2016 were not in scope for death statistics. Prior to 1 July 2016, deaths of people that occurred in Australia with a usual residence of Norfolk Island were included in Australian totals, but assigned a usual residence of 'overseas'. With the inclusion of Norfolk Island as a territory of Australia in the Australian Statistical Geography Standard (ASGS) 2016, those deaths which occurred in Australia between January and June 2016 with a usual residence of Norfolk Island were allocated to the Norfolk Island SA2 code instead of the 'overseas' category.  

This publication draws extensively on information provided freely by the state and territory Registries of Births, Deaths and Marriages, and the Victorian Department of Justice who manage the National Coronial Information System (NCIS). Their continued cooperation is very much appreciated: without it, the wide range of vitals statistics published by the ABS would not be available. Information received by the ABS is treated in strict confidence as required by the Census and Statistics Act 1905.

From the Causes of Death Australia, 2015 publication, data has been released approximately six months earlier than previous issues (2014 and prior). This was due to a number of improvements in the processing of demographic and cause of death information.

In compiling causes of death statistics, the ABS employs a variety of measures to improve quality, which include:

• providing certifiers with certification booklets for guidance in reporting causes of death on medical certificates, see Information Paper: Cause of Death Certification Australia, 2008;
• seeking detailed information from the National Coronial Information System (NCIS); and
• editing checks at the individual record and aggregate levels.

In response to the COVID-19 pandemic, the World Health Organization (WHO) issued the ICD emergency codes U07.1 COVID-19, virus identified and U07.2 COVID-19, virus not identified. These codes are used when assigning causes to confirmed or suspected COVID-19 deaths.

Due to the public health importance of COVID-19, the WHO directed that the new coronavirus strain be recorded as the underlying cause of death, i.e. the disease or condition that initiated the train of morbid events, when it is recorded as having caused death.

The number of deaths registered in 2020 (161,300) decreased by 8,001 deaths compared to 2019, but is similar to the average number of deaths recorded for 2015-2019 (161,252). All jurisdictions except the Australian Capital Territory recorded a decrease in deaths in 2020. The national decrease was influenced by two known factors. In 2019, Victoria provided an additional 2,739 deaths that were registered in 2017 and 2018. These deaths were within scope of the 2019 reference year and resulted in a higher-than-usual number of deaths in 2019. Following this, there were 2,781 fewer deaths registered in Victoria in 2020 (-6.3%), accounting for 34.8% of the national decrease. 

Additionally, fewer deaths due to respiratory diseases (including influenza) were recorded in the winter months of 2020, as a result of social distancing measures introduced in response to the COVID-19 pandemic. Influenza is a highly seasonal virus with the majority of cases typically occurring in cooler months. In 2020, 55 deaths were caused by influenza, the majority of which occurred between January and March. This compares to 1,080 influenza deaths in 2019, which was considered to be a severe influenza season.   

Lockdowns due to the COVID-19 pandemic influenced the number of birth registrations in Australia, with fewer births registered in 2020 compared to recent years. Births are used in the calculation of infant mortality rates, which are are presented per 1,000 live births.

As a result of joint investigations between the ABS and the Victorian Registry of Births Deaths and Marriages (Victorian RBDM) 2,812 death registrations from 2017, 2018 and 2019 were identified that had not previously been provided to the ABS. Of the 2,812 deaths, 40.4% were registered in 2017, 57.0% in 2018 and the remainder in 2019 (2.6%). An issue associated with the Registry's previous processing system (replaced in 2019) resulted in some death registrations not being delivered to the ABS in the year they were registered. The 2,812 Victorian deaths were in scope of the 2019 reference year and were therefore included in that issue for total deaths. 

Of the 2,739 deaths that were registered in 2017 and 2018 and submitted to the ABS for the 2019 reference year 63% were certified by a coroner with the remaining 37% certified by a doctor. This has led to an increase across a number of causes of death, with those more likely to be referred to a coroner (i.e. external causes of death) experiencing larger effects from the delayed delivery of registrations. 

A time series adjustment has been applied to deaths due to suicide, assault and accidental drug overdose to enable a more accurate comparison of mortality over time for these causes. See Technical note: Victorian additional registrations and time series adjustments in Causes of Death, Australia, 2019 for detailed information on this issue. 

In February 2019, the Victorian RBDM implemented a new registration system, with this also leading to a change in the way coroner referred deaths are reported to the ABS. Previously there were a range of factors that would determine the point at which a coroner referred death was reported to the ABS, often leading to significant delays in reporting. From 2019, this has changed and interim registrations (open cases) have been submitted to the ABS. This procedural change has resulted in an additional delay to registrations in 2018 and previous years, but the change to procedure led to more timely delivery of death registration information to the ABS.

In 2016 and 2017 there were lower than expected registration counts for New South Wales. The ABS worked with the NSW Registry of Births, Deaths and Marriages (NSW RBDM) to investigate these counts, highlighting that changes to identity requirements in 2016 had prevented some registrations from being finalised. The NSW RBDM worked with parents to finalise these registrations, enabling many to be included in 2018 counts. Other initiatives also contributed to the higher count of births in NSW in 2018, including the implementation of an online birth registration system and a campaign aimed at increasing registrations among Aboriginal and Torres Strait Islander parents.

In 2018, the Northern Territory Registry of Births, Deaths and Marriages identified a processing issue that led to delays in completing the registration of some births that occurred in previous years. These births have since been registered, resulting in 355 additional births being included in 2018 data, the majority of which (339) were of Aboriginal and Torres Strait Islander children. Care should be taken when interpreting changes in birth counts, infant death rates and fertility rates for the Northern Territory in recent years.

In November 2010, the Queensland Registrar of Births, Deaths and Marriages advised the ABS of an outstanding deaths registration initiative undertaken by the registry. This initiative resulted in the November 2010 registration of 374 previously unregistered deaths which occurred between 1992 and 2006 (including a few for which a date of death was unknown). Of these, around three-quarters (284) were deaths of Aboriginal and Torres Strait Islander Australians. A data adjustment is made for tables which include Aboriginal and Torres Strait Islander data for Queensland for 2010. For further information refer to Technical Notes, Registration of Outstanding Deaths, Queensland, 2010 in Deaths, Australia, 2010 and Retrospective Deaths by Causes of Death, Queensland, 2010, in Causes of Death, Australia, 2010.

In September quarter 2011 the high number of death registrations in New South Wales was queried with the New South Wales Registry of Births, Deaths and Marriages. Information provided by the Registry indicates that these fluctuations may be the result of changes in processing rates. This may have contributed to the increase in the number of deaths registered in New South Wales in 2011. New South Wales deaths in 2011 (50,182) were 5.8% higher than in 2010 (47,453).

For coroner certified deaths, the specificity of cause of death coding can be affected by the length of time for the coronial process to be finalised and the coroner case closed. To improve the quality of ICD coding, all coroner certified deaths registered after 1 January 2006 are subject to a revisions process.

Up to and including deaths registered in 2005, ABS Causes of Death processing was finalised at a point in time. At this point, not all coroners' cases had been investigated, the case closed and relevant information loaded into the National Coronial Information System (NCIS). The coronial process can take several years if an inquest is being held or complex investigations are being undertaken. In these instances, the cases remain open on the NCIS and relevant reports may be unavailable. Coroners' cases that have not been closed or had all information made available can impact on data quality as less specific ICD codes often need to be applied.

The revisions process to date has focused on cases that remain open on the NCIS database. ABS coders investigate and use additional information from police reports, toxicology reports, autopsy reports and coroners' findings to assign more specific causes of death. The use of this additional information occurs at either 12 or 24 months after initial processing and the specificity of the assigned ICD-10 codes increase over time. As 12 or 24 months pass after initial processing, many coronial cases are closed, with the coroner having dispensed a cause of death and relevant reports have been made available. This allows ABS coders to assign a more specific cause of death.

These published outputs include 2020 and 2019 preliminary data, 2018 revised data and 2017 final data. Final data for 2018 and revised data for 2019 will be released in early 2022.

Data cells with small values have been randomly assigned to protect confidentiality. As a result some totals will not equal the sum of their components. Cells with 0 values have not been affected by confidentialisation.

Where figures have been rounded, discrepancies may occur between totals and sums of the component items.

ABS published outputs are available free of charge from the ABS website. Click on 'Statistics' to gain access to the full range of ABS statistical and reference information. For details on products scheduled for release in the coming week, click on the Future Releases link on the ABS homepage.

A range of socio-demographic data is available from the ABS Causes of Death collection including age, sex, and Aboriginal and Torres Strait Islander origin. This data has been coded and presented on standard classifications developed by the ABS. Where these are not released in the Causes of Death published outputs, they can be sourced on request from the ABS. 

The Aboriginal and Torres Strait Islander origin is captured through the death registration process and coded and presented in this publication based on the ABS Indigenous Status classification, see Indigenous Status Standard, 2014.

Since the publication of Causes of Death, Australia, 2011, the ABS has released data based on the Australian Statistical Geography Standard (ASGS). The ASGS is a hierarchical classification system that defines more stable, consistent and meaningful areas than those of the Australian Standard Geographical Classification (ASGC), which was used to define geographical areas for output prior to the release of 2011 reference year data. Under the ASGS, causes of death statistics are coded to Statistical Area 2 (SA2) level, and are presented at the state/territory and national level in this publication. For further information, refer to the Australian Statistical Geography Standard (ASGS): Volume 1 - Main Structure and Greater Capital City Statistical Areas, July 2016.

Causes of death statistics for states and territories in this publication have been compiled based on the state or territory of usual residence of the deceased, regardless of where in Australia the death occurred and was registered. Deaths of persons usually resident overseas which occur in Australia are included in the state/territory in which their death was registered.

The country of birth of the deceased is coded and presented based on the Standard Australian Classification of Countries (SACC). This classification groups neighbouring countries into progressively broader geographic areas on the basis of their similarity in terms of social, cultural, economic and political characteristics. For further information, refer to the Standard Australian Classification of Countries (SACC).

The International Classification of Diseases (ICD) is the international standard classification for epidemiological purposes and is designed to promote international comparability in the collection, processing, classification, and presentation of causes of death statistics. The classification is used to classify diseases and causes of disease or injury as recorded on many types of medical records as well as death records. The ICD has been revised periodically to incorporate changes in the medical field. Currently the ICD 10th revision is used for Australian causes of death statistics.

The ICD-10 is a variable-axis classification meaning that the classification does not group diseases only based on anatomical sites, but also on the type of disease. Epidemiological data and statistical data is grouped according to:

• epidemic diseases;
• constitutional or general diseases;
• local diseases arranged by site;
• developmental diseases; and
• injuries.

For example, a systemic disease such as sepsis is grouped with infectious diseases; a disease primarily affecting one body system, such as a myocardial infarction, is grouped with circulatory diseases; and a congenital condition, such as spina bifida, is grouped with congenital conditions.

For further information about the ICD refer to WHO International Classification of Diseases (ICD).

The versions of the ICD 10th Revision are available online.

The Update and Revision Committee (URC), a WHO advisory group on updates to ICD-10, maintains the cumulative and annual lists of approved updates to the ICD-10 classification. The updates to ICD-10 are of numerous types including the addition and deletion of codes, changes to coding instructions and modification and clarification of terms.

From the 2013 reference year, the ABS implemented a new automated coding system called Iris. The 2013-2020 data coded in the Iris system applied updated versions of the ICD-10 when coding multiple causes of death, and when selecting the underlying cause of death. The 2020 reference year causes of death data presented in this publication was coded using version 5.8.0 of Iris software. Version 5.8.0 applied the WHO ICD-10 updates (2020 version) which have resulted in minor changes to output. More information on Iris and ICD-10 versioning can be found in the table below. For details of further impacts of this change from 2013 data onwards, see the ABS Implementation of the Iris Software: Understanding Coding and Process Improvements Technical Note, in the Causes of Death, Australia, 2013 publication.

In response to the COVID-19 pandemic, the World Health Organization (WHO) issued the ICD emergency codes U07.1 COVID-19, virus identified and U07.2 COVID-19, virus not identified. These codes are used when assigning causes to confirmed or suspected COVID-19 deaths.

Due to the public health importance of COVID-19, the WHO directed that the new coronavirus strain be recorded as the underlying cause of death, i.e. the disease or condition that initiated the train of morbid events, when it is recorded as having caused death.

With the introduction of 2019 ICD-10 updates there was a change to the code for deaths due to poisoning by and exposure to carbon monoxide and other gases and vapours. This change was applied to poisoning across multiple intents including accident (X47), intentional (X67), assault (X88) and undetermined intent (Y17). There are now multiple fourth-digit options for X47, X67, X88 and Y17. Previously, when a death occurred as a result of poisoning by and exposure to carbon monoxide and other gases and vapours, there was no option to further identify carbon monoxide from other gases and vapours as well as to specify the source of the carbon monoxide. ABS mortality coders are now required to choose from multiple fourth-digit options to further specify the death:

• X470/X670/X880/Y170 carbon monoxide from combustion engine exhaust 
• X471/X671/X881/Y172 carbon monoxide from utility gas
• X472/X672/X882/Y172 carbon monoxide from other domestic fuels
• X473/X673/X883/Y173 carbon monoxide from other sources
• X474/X674/X884/Y173 carbon monoxide from unspecified sources 
• X478/X678/X888/Y178 other specified gases and vapours 
• X479/X679/X889/Y179 unspecified gases and vapours 

Prior to the 2013 reference year, the 2006 version of the ICD-10 was the most recent version used for coding deaths, with the exception of two updates that were applied after the 2006 reference year. The first update was implemented in 2007 and related to the use of mental and behavioural disorders due to psychoactive substance use, acute intoxication (F10.0, F11.0...F19.0) as an underlying cause of death. If the acute intoxication initiated the train of morbid events it is now assigned an external accidental poisoning code (X40-X49) corresponding to the type of drug used. For example, if the death had been due to alcohol intoxication, the underlying cause before the update was F10.0, and after the update the underlying cause is X45, with poisoning code T51.9. The second update implemented from the 2009 reference year was the addition of Influenza due to certain identified virus (J09) to the Influenza and Pneumonia block. This addition was implemented to capture deaths due to Swine flu and Avian flu, which were reaching health epidemic status worldwide.

The cumulative list of ICD-10 updates can be found online.

Conditions on the medical certificate of cause of death are coded to the International Classifications of Diseases, 10th revision (see Classifications section of the methodology for more information). All causes of death can be grouped to describe the type of death, whether it be from a disease or condition, or from an injury, or whether the cause is unknown. These are generally described as:

• Natural Causes - deaths due to diseases (for example diabetes, cancer, heart disease etc.) (A00-Q99, R00-R98)
• External Causes - deaths due to causes external to the body (for example intentional self-harm, transport accidents, falls, poisoning etc.) (V01-Y98)
• Unknown Causes - deaths where it is unable to be determined whether the cause was natural or external (R99).

Where an accidental or violent death occurs, the underlying cause is classified according to the circumstances of the fatal injury, rather than the nature of the injury, which is coded separately. For example, a motorcyclist may crash into a tree (V27.4) and sustain multiple fractures to the skull and facial bones (S02.7), which leads to death. The underlying cause of death is the crash itself (V27.4), as it is the circumstance which led to the injuries that ultimately caused the death.

From the 2013 reference year, the ABS implemented a new automated coding system called Iris. The 2013-2020 data coded in the Iris system applied updated versions of the ICD-10 when coding multiple causes of death, and when selecting the underlying cause of death. The 2020 reference year causes of death data presented in this publication was coded using version 5.8.0 of Iris software. Version 5.8.0 applied the WHO ICD-10 updates (2020 version) which have resulted in minor changes to output. More information on Iris and ICD-10 versioning can be found in the table below. For details of further impacts of this change from 2013 data onwards, see the ABS Implementation of the Iris Software: Understanding Coding and Process Improvements Technical note, in the Causes of Death, Australia, 2013 publication and Updates to Iris coding software: Implementing WHO updates and improvements in coding processes Technical note, in the Causes of Death, Australia, 2018 publication.

The quality of causes of death coding can be affected by changes in the way information is reported by certifiers, by lags in completion of coroner cases and the processing of the findings. While changes in reporting and lags in coronial processes can affect coding of all causes of death, those coded to Chapter XVIII: Symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified and Chapter XX: External causes of morbidity and mortality are more likely to be affected because the code assigned within the chapter may vary depending on the coroner's findings (in accordance with ICD-10 coding rules).

Where a case remains open on the NCIS at the time the ABS ceases processing, and insufficient information is available to code a cause of death (e.g. a coroner certified death was yet to be finalised by the coroner), less specific ICD codes are assigned, as required by the ICD coding rules.

The specificity with which open cases are able to be coded is directly related to the amount and type of information available on the NCIS. The amount of information available for open cases varies considerably from no information to detailed police, autopsy and toxicology reports. There may also be interim findings of 'intent'.

The manner or intent of an injury which leads to death, is determined by whether the injury was inflicted purposefully or not. When it was inflicted purposefully (intentional), a determination should be made as to whether the injury was self-inflicted (suicide) or inflicted by another person (assault). However, intent cannot be determined in all cases.

ICD-10 codes are assigned to all conditions on a medical certificate of cause of death and rules applied to select an underlying cause of death. The WHO defines the underlying cause of death as the disease or injury that initiated the train of morbid events leading directly to death. Accidental and violent deaths are classified according to the external cause, that is, to the circumstances of the accident or violence which produced the fatal injury rather than to the nature of the injury. The majority of data presented in the datacubes in this publication is tabulated according to the underlying cause of death. 

Multiple causes of death include all causes and conditions reported on the death certificate (i.e. both underlying and associated causes; see the Glossary for further details). As all entries on the death certificate are taken into account, multiple causes of death statistics are valuable in recognising the impact of conditions and diseases which are less likely to be an underlying cause, highlighting relationships between concurrent disease processes, and giving an indication of injuries which occur as a result of specific external events. These features of multiple causes of death data provide a more in depth picture of mortality in Australia.

When analysing data on multiple causes of death, data can be presented in two ways: by counts of deaths or by counts of mentions. When analysis is conducted by counts of death, the figures are describing the number of people who have died with a particular disease or disorder. Multiple Causes of Death data derived from counts of mentions is the total number of incidences of a particular disease or disorder on the death certificate. For example, an individual may have had Breast cancer (C50) and then developed Secondary lung cancer (C78.0). This individual would be counted once if counts were by the number of deaths from cancer, but twice if the counts were by the number of mentions of cancer. Care should be taken to differentiate between counts and mentions when analysing multiple causes of death data.

Changes in patterns of mortality are studied by policy makers and researchers to improve health outcomes for all Australians. However, changes in patterns of mortality can occur for many reasons. Changes can reflect a real increase or decrease in the prevalence of a disease or disorder, or a change in medical treatment. Mortality data changes can also be a result of administrative processes which can potentially impact on the data, for example, International Classification of Disease (ICD) coding classification changes and updates, and differences in how deaths are certified. Analysis of the multiple causes of death data can give a deeper understanding of how the complete dataset may be affected by both real and administrative changes. For example, in 2009, the World Health Organization (WHO) recommended introducing code J09 (Influenza due to certain identified influenza virus) to the ICD-10 in response to the worldwide epidemics of swine flu and avian flu. There were 98 people who died as a direct consequence of contracting these strains of the flu across 2009 and 2010. In addition there were 51 people who had this flu when they died and for whom this would have been a complicating factor. Additional health risk factors may also be identified. When swine or avian flu was the underlying cause of death, multiple causes data shows obesity and respiratory problems as a common associated cause. In this way, multiple causes data provides policy makers and researchers a greater insight beyond the underlying cause of death. 

As part of a collection-wide initiative by the ABS to improve specificity of cause of death coding in the 2008 and 2009 reference years, doctor certified deaths due to Pneumonia, organism unspecified (J18) reduced substantially. This was as a result of the ABS manually interrogating conditions located in Part 2 of the Medical Certificate Cause of Death (MCCD), reallocating them to a more specific cause of death code.

In 2010 there was a shift in this pattern. The number of doctor certified deaths assigned to J18 increased by 690 deaths, or 49.5%. The reason for the 2010 data movement was a more consistent use of coding software decision tables throughout both coding and quality assurance processes. These decision tables provide clear rules for when Pneumonia can be selected as an underlying cause of death, in relation to the information listed in Part 2 of the MCCD.

The 2010 increase represented a return to counts observed prior to 2008. In 2007, 2,293 doctor certified deaths were assigned to J18, therefore the 2010 count for this cause of death (2,085) is considered a return to the trend which existed prior to the coding of 2008 and 2009 data. The data from 2011 onwards has been consistent with this trend.

There were 1,239 deaths attributed to road crashes (V01-V79, V892, X82, Y32) in 2020. Of these, 60 were of suicidal intent (X82) and there were a further 16 where the intent could not be determined (Y32). When making comparisons between road deaths from the ABS Causes of Death collection and road deaths from other sources, the scope and coverage rules applying to each collection should be considered. It should be noted that the number of road-traffic-related deaths attributed to transport accidents for 2020 is expected to change as data is subject to the revisions process.

There were 77 transport accidents (V00-V99) that were registered in Victoria in 2017 and 2018 but not supplied to the ABS as an official death registration until 2019. These 77 deaths are included in the 2019 reference year data for Victoria and Australia totals of transport accidents. For more information refer to Technical note: Victorian additional registrations and time series adjustments in Causes of Death, Australia, 2019. 

The number of deaths attributable to Accident to watercraft causing drowning and submersion (V90) increased from 26 in 2010 to 75 in 2011. This increase is primarily due to deaths resulting from an incident in December 2010 when a boat collided with cliffs on Christmas Island. These deaths were registered with the Western Australian Registry of Births, Deaths and Marriages in January 2011, resulting in an increase in the number of deaths coded to V90 in Western Australia.

The number of deaths recorded as Assault (X85-Y09, Y87.1) i.e. murder, manslaughter and their sequelae, published in the ABS Causes of Death publication, differ from those published by the ABS in Recorded Crime - Victims, Australia. Reasons for the different counts include differences in scope and coverage between the two collections, as well as legal proceedings that are pending finalisation. It is important to note that the number of deaths attributed to assault for 2020 is expected to change as data is subject to the revisions process. See Causes of Death Revisions, 2017 Final Data (Technical Note) and 2018 Revised Data (Technical Note) in Causes of Death, Australia, 2019.

There were 28 deaths due to assault that were registered in Victoria in 2017 (13 deaths) and 2018 (15 deaths) that were not submitted to the ABS until the 2019 reference year. These deaths are included in the total number of all cause deaths for 2019 in line with ABS scope of mortality data. When analysing assaults as an individual cause of death a time series adjustment has been applied and these 28 deaths have been reassigned to their respective registration years in the data cubes of this publication. 

Ranking causes of death is a useful method of describing patterns of mortality in a population and allows comparison over time and between populations. However, different methods of grouping causes of death can result in a vastly different list of leading causes for any given population. A ranking of leading causes of death based on broad cause groupings such as 'cancers' or 'heart disease' does not identify the leading causes within these groups, which is needed to inform policy on interventions and health advocacy. Similarly, a ranking based on very narrow cause groupings or including diseases that have a low frequency, can be meaningless in informing policy.

Tabulations of leading causes presented in this publication are based on research presented in the Bulletin of the World Health Organization, Volume 84, Number 4, April 2006, 297-304. The determination of groupings in this list is primarily driven by data from individual countries representing different regions of the world. Other groupings are based on prevention strategies, or to maintain homogeneity within the groups of cause categories. Since the aforementioned bulletin was published, a decision was made by WHO to include deaths associated with the H1N1 influenza strain (commonly known as swine flu) in the ICD-10 classification as Influenza due to certain identified influenza virus (J09). This code has been included with the Influenza and Pneumonia leading cause grouping in the Causes of Death publication since the 2009 reference year.

Since 2015, 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 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. This change has been applied in this publication to data for all reference years that appear in tables involving leading cause tabulations. This differs to publications prior to 2015, for which C26.0 was not included in this leading cause grouping, and also differs to the suggested WHO tabulation of leading causes for these cancers. Comparisons with data for this leading cause, and associated leading cause rankings, as they appear in previous publications should therefore be made with caution. Time-series data by leading causes has been published in Australia's leading causes of death in this publication.

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 change has been applied to harmonise data between the WHO leading cause grouping and subject specific datacubes for intentional self-harm, assault and transport accidents which is published as part of the ABS Causes of Death collection. This change applies to publication data for all reference years that appear in tables involving leading cause tabulations. This differs to previous publications, where Y87.0, Y87.1 and Y85 were not included in these leading cause groupings, and also differs to the suggested WHO tabulation of leading causes. Comparisons with data for these leading causes, and associated leading cause rankings, as they appear in previous publications should therefore be made with caution. Time-series data by leading causes has been published in Australia's leading causes of death in this publication.

Age-standardised death rates enable the comparison of death rates over time and between populations of different age-structures. Along with adult, infant and child mortality rates, they are used to determine whether the mortality rate of the Aboriginal and Torres Strait Islander population is declining over time, and whether the gap between Aboriginal and Torres Strait Islander and non-Indigenous populations is narrowing. However, there have been inconsistencies in the way different government agencies have calculated age-standardised death rates in the past. The ABS uses the direct method of age-standardisation as it allows for valid comparisons of mortality rates between different study populations and across time. This method was agreed to by the ABS, Australian Institute of Health and Welfare (AIHW) and other stakeholders. For further information see: AIHW (2011) Principles on the use of direct age-standardisation in administrative data collections: for measuring the gap between Indigenous and non-Indigenous Australians. Cat. no. CSI 12. Canberra: AIHW.

The direct method has been used throughout the publication and data cubes for age-standardised death rates. Age-standardised death rates for specific causes of death with fewer than a total of 20 deaths have not been published due to issues of robustness.

For further information, see Appendix: Principles on the use of direct age-standardisation, from Deaths, Australia, 2010.

In this publication, age-standardised and age-specific death rates for Aboriginal and Torres Strait Islander persons for the 2010-2020 reference years have been calculated using 2016-Census-based population estimates (projections and backcasts). Non-Indigenous estimates have been derived by subtracting the 2016-census based Aboriginal and Torres Strait Island population estimates from the total 2016-Census-based estimated resident population (ERP). Rates calculated from population denominators derived from different Censuses may cause artificially large rate differences. Rate comparisons should not be made with previous publications for Aboriginal and Torres Islander data. See Estimates and Projections, Aboriginal and Torres Strait Islander Australians for more information.

There are standard ways for listing causes of death and there are formal recommendations concerning lists for tabulation to assist international comparisons. The World Health Organization (WHO) provides a number of standard tabulation lists for presentation of causes of death statistics, that assist international comparability. WHO also recommend that when there is not a need for international comparability then lists should be designed to reflect local requirements. These special lists can be developed, for example, to monitor progress of local health programs.

Causes of death attributable to firearm mortality include ICD-10 codes:

W32-W34, Accidental discharge of firearms; 
X72-X74, Intentional self-harm (suicide) by discharge of firearms; 
X93-X95, Assault (homicide) by discharge of firearms; 
Y22-Y24, Discharge of firearms, undetermined intent; and 
Y35.0, Legal intervention involving firearm discharge.

Deaths from injury by firearms exclude deaths due to explosives and other causes indirectly related to firearms.

The data presented for drug-induced deaths in this publication is based upon tabulation created by the United States Centers for Disease Control and Prevention (CDC).

Causes of death attributable to drug-induced mortality include ICD-10 codes:

D52.1, Drug-induced folate deficiency anaemia;
D59.0, Drug-induced haemolytic anaemia;
D59.2, Drug-induced nonautoimmune haemolytic anaemia;
D61.1, Drug-induced aplastic anaemia;
D64.2, Secondary sideroblastic anaemia due to drugs and toxins;
E06.4, Drug-induced thyroiditis;
E16.0, Drug-induced hypoglycaemia without coma;
E23.1, Drug-induced hypopituitarism;
E24.2, Drug-induced Cushing’s syndrome;
E27.3, Drug-induced adrenocortical insufficiency;
E66.1, Drug-induced obesity;
F11.0-F11.5, Use of opioids causing intoxication, harmful use (abuse), dependence, withdrawal or psychosis
F11.7-F11.9, Use of opioid causing late onset psychosis, other mental and behavioural disorders and unspecified behavioural disorders.
F12.0-F12.5, Use of cannabis causing intoxication, harmful use (abuse), dependence, withdrawal or psychosis
F12.7-F12.9, Use of cannabis causing late onset psychosis, other mental and behavioural disorders and unspecified behavioural disorders. 
F13.0-F13.5, Use of sedative or hypnotics causing intoxication, harmful use (abuse), dependence, withdrawal or psychosis
F13.7-F13.9, Use of sedative or hypnotics causing late onset psychosis, other mental and behavioural disorders and unspecified behavioural disorders.
F14.0-F14.5, Use of cocaine causing intoxication, harmful use (abuse), dependence, withdrawal or psychosis
F14.7-F14.9, Use of cocaine causing late onset psychosis, other mental and behavioural disorders and unspecified behavioural disorders.
F15.0-F15.5, Use of caffeine causing intoxication, harmful use (abuse), dependence, withdrawal or psychosis
F15.7-F15.9, Use of caffeine causing late onset psychosis, other mental and behavioural disorders and unspecified behavioural disorders.
F16.0-F16.5, Use of hallucinogens causing intoxication, harmful use (abuse), dependence, withdrawal or psychosis
F16.7-F16.9, Use of hallucinogens causing late onset psychosis, other mental and behavioural disorders and unspecified behavioural disorders.
F18.0-F18.5, Use of volatile solvents causing intoxication, harmful use (abuse), dependence, withdrawal or psychosis
F18.7-F18.9, Use of volatile solvents causing late onset psychosis, other mental and behavioural disorders and unspecified behavioural disorders.
F19.0-F19.5, Use of multiple drugs and other psychoactive substances causing intoxication, harmful use (abuse), dependence, withdrawal or psychosis
F19.7-F19.9, Use of multiple drugs and other psychoactive substances causing late onset psychosis, other mental and behavioural disorders and unspecified behavioural disorders.
G21.1, Other drug-induced secondary Parkinsonism;
G24.0, Drug-induced dystonia;
G25.1, Drug-induced tremor;
G25.4, Drug-induced chorea;
G25.6, Drug-induced tics and other tics of organic origin;
G44.4, Drug-induced headache, not elsewhere classified;
G62.0, Drug-induced polyneuropathy;
G72.0, Drug-induced myopathy;
I95.2, Hypotension due to drugs;
J70.2, Acute drug-induced interstitial lung disorders;
J70.3, Chronic drug-induced interstitial lung disorders;
J70.4, Drug-induced interstitial lung disorder, unspecified;
L10.5, Drug-induced pemphigus;
L27.0, Generalized skin eruption due to drugs and medicaments;
L27.1, Localized skin eruption due to drugs and medicaments;
M10.2, Drug-induced gout;
M32.0, Drug-induced systemic lupus erythematosus;
M80.4, Drug-induced osteoporosis with pathological fracture;
M81.4, Drug-induced osteoporosis;
M83.5, Other drug-induced osteomalacia in adults;
M87.1, Osteonecrosis due to drugs;
R78.1, Finding of opiate drug in blood;
R78.2, Finding of cocaine in blood;
R78.3, Finding of hallucinogen in blood;
R78.4, Finding of other drugs of addictive potential in blood;
R78.5, Finding of psychotropic drug in blood;
X40-X44, Accidental poisoning by and exposure to drugs, medicaments and biological substances;
X60-X64, Intentional self-poisoning (suicide) by and exposure to drugs, medicaments and biological substances;
X85, Assault (homicide) by drugs, medicaments and biological substances; and
Y10-Y14, Poisoning by and exposure to drugs, medicaments and biological substances, undetermined intent.

Drug-induced causes exclude accidents, homicides, and other causes indirectly related to drug use. Also excluded are newborn deaths associated with mother’s drug use.

The data presented for opioid-induced deaths in this publication is a modified version of the drug-induced deaths tabulation created by the United States Centers for Disease Control and Prevention (CDC). To capture opioid-induced deaths, the following poisoning codes present at the multiple causes of death level were used in combination with the CDC drug-induced underlying cause of death tabulation.

Causes of death attributable to opioids include ICD-10 codes present at the multiple causes of death level:

T40.0, Opium;
T40.1, Heroin;
T40.2, Other opioids (e.g. Codeine, Morphine);
T40.3, Methadone;
T40.4, Other synthetic narcotics (e.g. Pethidine); and
T40.6, Other and unspecified narcotics.

Causes of death attributable to alcohol-induced mortality include ICD-10 codes:

E24.4, Alcohol-induced pseudo-Cushing’s syndrome; 
F10, Mental and behavioural disorders due to alcohol use; 
G31.2, Degeneration of nervous system due to alcohol; 
G62.1, Alcoholic polyneuropathy; 
G72.1, Alcoholic myopathy; 
I42.6, Alcoholic cardiomyopathy; 
K29.2, Alcoholic gastritis; 
K70, Alcoholic liver disease; 
K85.2 Alcohol-induced acute pancreatitis;
K86.0, Alcohol-induced chronic pancreatitis; 
R78.0, Finding of alcohol in blood; 
X45, Accidental poisoning by and exposure to alcohol; 
X65, Intentional self-poisoning by and exposure to alcohol; and 
Y15, Poisoning by and exposure to alcohol, undetermined intent.

Alcohol-induced causes exclude accidents, homicides, and other causes indirectly related to alcohol use. This category also excludes newborn deaths associated with maternal alcohol use.

1. Miniño AM, Heron MP, Murphy SL, Kochankek, KD. Deaths: Final Data for 2004. National vital statistics reports; vol 55 no 19. Hyattsville, MD: National Center for Health Statistics. 2007.

Causes of death attributable to Non-Communicable Diseases include ICD-10 codes:

C00-C97, D45-D46, D47.1, D47.3-D47.5, Cancers;
I00-I99, Cardiovascular diseases;
E10-E14, Diabetes; and
J30-J98, Chronic lower respiratory diseases.

2. World Health Organization (WHO). Non-Communicable Diseases Global Monitoring Framework: Indicator Definitions and Specifications. Note: The WHO Cancer tabulation for NCDs includes only C00-C97. To be consistent with ABS Causes of Death reporting additional cancer codes (D45-D46, D47.1, D47.3-D47.5) are recommended for inclusion when analysing cancer related NCDs.

The ABS accesses the National Coronial Information System (NCIS) to obtain causes of death information for coroner referred deaths including suicides. Information regarding the causes of death and associated factors is obtained from various reports including police, toxicology, autopsy and coronial findings.

The number of deaths attributed to intentional self-harm for 2020 is expected to increase as data is subject to the revisions process. For further information, see the Revisions section in Data quality of the methodology and the Causes of Death Revisions, 2017 Final Data (Technical Note) and 2018 Revised Data (Technical Note) in Causes of Death, Australia, 2019.

From 2006 onwards, the ABS implemented a revisions process for coroner certified deaths (such as suicides), which has enabled additional suicide deaths to be identified beyond initial processing. It is recognised that in the four years prior to the implementation of the revisions process (2002-2005), suicide deaths may have been understated as the ABS began using the National Coronial Information System as the sole source for coding coroner referred deaths.

In addition to the revisions process, new coding guidelines were applied for deaths registered from 1 January 2007. The new guidelines improve data quality by enabling deaths to be coded to suicide if evidence indicates the death was from intentional self-harm. Previously, coding rules required a coroner to determine a death as intentional self-harm for it to be coded to suicide. However, in some instances the coroner does not make a finding on intent. The reasons for this may include legislative or regulatory barriers around the requirement to determine intent, or sensitivity to the feelings, cultural practices and religious beliefs of the family of the deceased. Further, for some mechanisms of death it may be very difficult to determine suicidal intent (e.g. single vehicle incidents, drowning). In these cases the burden of proof required for the coroner to establish that the death was as a result of intentional self-harm may make a finding of suicide less likely.

Under the new coding guidelines, in addition to coroner-determined suicides, deaths may also be coded to suicide following further investigation of information on the NCIS. Further investigation of a death would be initiated when the mechanism of death indicates a possible suicide and the coroner does not specifically state the intent as accidental or homicidal. Information that would support a determination of suicide includes indications by the person that they intended to take their own life, the presence of a suicide note, or knowledge of previous suicide attempts. The processes for coding open and closed coroner cases are illustrated in the below diagrams (open/closed case coding decision trees).

Over time, the NCIS has worked with jurisdictions to improve the timeliness and completeness of information flowing from the coronial systems to the NCIS database. These improvements lead to changes in the information available to ABS coding staff. It is therefore important that data users are aware of any significant improvements in the management of coronial data to enable better interpretation of data within, and between, reference periods.

Coronial cases are more likely to be affected by a lag in registration time, especially those which are due to external causes, including suicide, homicide and drug-related deaths. Due to small numbers these lagged coroner referred registrations can create large yearly variation in some causes of deaths of Aboriginal and Torres Strait Islander people. Caution should be taken when making year to year analysis.

More broadly, change in administrative systems highlights how various factors (including administrative and system changes, certification practices, classification updates or coding rule changes) can impact on the mortality dataset. Data users should note this particular change and be cautious when making comparisons between reference periods. The change does not explain away differences between years, but is a factor to consider. It should also be noted as a factor that may influence the magnitude of any increases in suicide numbers as revisions are applied.

The two flow charts below highlight the guidelines used by the ABS when coding a death to intentional self-harm for open and closed coroner cases, where the intent status at the time of coding is neither intentional self-harm nor assault. In these cases, the ABS considers additional information available on NCIS, such as the mechanism and other available data (e.g. the presence of a suicide note or previous suicide attempts) when determining the intent of such deaths for coding purposes.

There were 180 suicides that were registered in Victoria in 2017 (88 suicides) and 2018 (92 suicides) but not supplied to the ABS until 2019. Whilst these are included in overall total numbers of all cause deaths for 2019 in line with ABS scope rules, a time series adjustment has been made to Victorian suicides to more accurately reflect the pattern of registration of suicides deaths. See Technical note: Victorian additional registrations and time series adjustment in Causes of Death, Australia, 2019 for more information. 

In 2012, the implementation of JusticeLink in the NSW coronial system significantly changed how information is exchanged between the NSW coroners courts and the NCIS. This system enables nightly uploads of all new information to the NCIS, and as a result information pertaining to NSW coronial cases is available earlier in the investigation process and the information is more complete for the purposes of coding causes of death.

There is evidence that the system change in NSW has improved the quality of preliminary coding in relation to deaths due to intentional self-harm. There has been an increase in the number of preliminary intentional self-harm deaths registered in NSW when comparing counts for 2012 onwards with those of 2011, coupled with fewer cases of deaths of undetermined intent (Y10-Y34).

The Aboriginal and Torres Strait Islander origin of a deceased person is captured through the death registration process. It is noted on the Death Registration Form and the Medical Certificate of Cause of Death. However it is recognised that not all such deaths are captured through these processes, leading to under-identification. While data is provided to the ABS for the Aboriginal and Torres Strait Islander origin of the deceased for around 99% of all deaths, there are concerns regarding the accuracy of the data.

The ABS Death Registrations collection identifies a death as being of an Aboriginal and Torres Strait Islander person where the deceased is recorded as Aboriginal, Torres Strait Islander, or both on the Death Registration Form (DRF). The Aboriginal and Torres Strait Islander origin is also derived from the Medical Certificate of Cause of Death (MCCD) for South Australia, Western Australia, Tasmania, the Northern Territory and the Australian Capital Territory from 2007. From 2015 data onwards, the Queensland Registry of Births, Deaths and Marriages also used MCCD information to derive the Aboriginal and Torres Strait Islander origin. For New South Wales and Victoria, the Aboriginal and Torres Strait Islander origin of the deceased is derived from the DRF only. If the Aboriginal and Torres Strait Islander origin reported in the DRF does not agree with that in the MCCD, an identification from either source that the deceased was an Aboriginal and/or Torres Strait Islander person is given preference over non-Indigenous or an unknown status.

There are several data collection forms on which people are asked to state whether they are of Aboriginal and Torres Strait Islander origin. Due to a number of factors, the results are not always consistent. The likelihood that a person will identify, or be identified, as an Aboriginal and Torres Strait Islander person on a specific form is known as their propensity to identify.

Propensity to identify as an Aboriginal and Torres Strait Islander person is determined by a range of factors, including:

• how the information is collected (e.g. census, survey, or administrative data);
• who provides the information (e.g. the person in question, a relative, a health professional, or an official);
• the perception of why the information is required, and how it will be used;
• educational programs about identifying as an Aboriginal and Torres Strait Islander person; and
• cultural aspects and feelings associated with identifying as Aboriginal and Torres Strait Islander Australian.

In addition to those deaths where the deceased is identified as an Aboriginal and Torres Strait Islander person, a number of deaths occur each year for which the Aboriginal and Torres Strait Islander origin is not stated on the death registration form. In 2020, there were 1,195 deaths registered in Australia for whom the Aboriginal and Torres Strait Islander origin was not stated, representing 0.7% of all deaths registered, a slight decrease from 2019 (0.8%). This difference was largely driven by fewer deaths with a not stated Aboriginal and Torres Strait Islander origin registered in New South Wales (from 728 in 2019 to 538 in 2020). 

Data presented in this publication may therefore underestimate the level of Aboriginal and Torres Strait Islander deaths and mortality in Australia. Caution should be exercised when interpreting data for Aboriginal and Torres Strait Islander Australians presented in this publication, especially with regard to year to year changes. 

Information on causes of death relating to Aboriginal and Torres Strait Islander persons is included in articles throughout this publication. Data cube 12 also provides information on causes of death for Aboriginal and Torres Strait Islander Australians. In Data cube 12, numbers and rates of death are reported by jurisdiction of usual residence for New South Wales, Queensland, South Australia, Western Australia and the Northern Territory only. Data for Victoria, Tasmania and the Australian Capital Territory has been excluded in line with national reporting guidelines. 

Individual state/territory disaggregations of deaths of Aboriginal and Torres Strait Islander Australians by WHO Leading Causes for the 2020 reference year are presented for New South Wales, Queensland, Western Australia and the Northern Territory only. No data is presented for South Australia, due to the small number of deaths by WHO leading causes - most causes have a count of fewer than 20 deaths, which is too small for the production of robust age-standardised death rates (SDRs). 

In this publication, age-standardised and age-specific death rates for Aboriginal and Torres Strait Islander persons for the 2011-2020 reference years have been calculated using 2016 Census-based population estimates (projections and backcasts). Non-Indigenous estimates have been derived by subtracting the 2016 Census-based Aboriginal and Torres Strait Islander population estimates from the total 2016 Census-based estimated resident population (ERP). Rates calculated from population denominators derived from different Censuses may cause artificially large rate differences. Rate comparisons should not be made with previous publications for Aboriginal and Torres Islander data. See Estimates and Projections, Aboriginal and Torres Strait Islander Australians, 2006 to 2031 for more information.

Coronial cases are more likely to be affected by a lag in registration time, especially those which are due to external causes, including suicide, homicide and drug-induced deaths. Due to small numbers these lagged coroner-referred registrations can create large yearly variation in some causes of deaths of Aboriginal and Torres Strait Islander people. Caution should be taken when making year to year comparisons.

The ABS undertakes significant work aimed at improving Aboriginal and Torres Strait Islander identification. The ABS works closely with the state and territory RBDMs through the Civil Registration and Vital Statistics Australasia committee (CRVSA) to progress strategies aimed at improving Indigenous identification in a nationally consistent way.

Quality studies conducted as part of the Census Data Enhancement (CDE) project have investigated the levels and consistency of Aboriginal and Torres Strait Islander identification between the 2011 Census and death registrations. See Information Paper: Death registrations to Census linkage project - Methodology and Quality Assessment, 2011-2012 (cat. no. 3302.0.55.004).

An assessment of various methods for adjusting incomplete Aboriginal and Torres Strait Islander death registration data for use in compiling Aboriginal and Torres Strait Islander life tables and life expectancy estimates is presented in Discussion Paper: Assessment of Methods for Developing Life Tables for Aboriginal and Torres Strait Islander Australians, 2006 (cat. no. 3302.0.55.002), released on 17 November 2008. Final tables based on feedback received from this discussion paper, using information from the Census Data Enhancement (CDE) study, can be found in Life Tables for Aboriginal and Torres Strait Islander Australians, 2010-2012 (cat. no. 3302.0.55.003).

The scope of the perinatal death statistics includes all registered fetal deaths (at least 20 weeks' gestation or at least 400 grams' birth weight) and all registered neonatal deaths (all live born babies who die within 28 completed days of birth, regardless of gestation or birth weight). The ABS scope rules for fetal deaths are consistent with the legislated requirement for all state and territory Registries of Births, Deaths and Marriages to register all fetal deaths which meet the above-mentioned gestation and birth weight criteria. Based on this legislative requirement, in the case of missing gestation and/or birth weight data, the fetal record is considered in scope and included in the dataset. A record is only considered out of scope if both gestation and birth weight data are present, and both fall outside the scope criteria (i.e. gestation of 19 weeks or less and birth weight of 399 grams or fewer). This scope was adopted for the 2007 Perinatal Deaths collection, and was applied to historical data for 1999-2006. For more information on the changes in scope rules see Perinatal Deaths, Australia, 2007 (cat. no. 3304.0) Explanatory Notes 18-20. These rules have been applied to all perinatal data presented in this publication.

The World Health Organization (WHO) definition of a perinatal death differs to that used by the ABS. The WHO definition includes all neonatal deaths, and those fetuses weighing at least 500 grams or having a gestational age of at least 22 weeks. A summary table based on the WHO definition of perinatal deaths is included in the Perinatal data cube in this release. See Coding of perinatal deaths below for more details on the interpretation of this table.

Fetal deaths are registered only as a stillbirth, and are not in scope of either the Births, Australia or Deaths, Australia collections. Fetal deaths are part of the Perinatal collection, but not the Causes of Death collection. Neonatal deaths are in scope of the Deaths, Causes of Death and Perinatal collections.

Given the small number of perinatal deaths which occur in some states and territories, some data provided on a state/territory basis in this publication has been aggregated for South Australia, Western Australia, the Northern Territory, the Australian Capital Territory and Other Territories.

This publication only includes information on registered fetal and neonatal deaths. Registered deaths are sourced through jurisdictional Registries of Births, Deaths and Marriages. This scope differs from other Australian data sources on perinatal deaths. For this reason alternative datasets are not directly comparable and caution should be taken when using multiple sources for analysis.

Perinatal death data reported by the ABS is not comparable with the National Perinatal Mortality Data Collection (NPMDC) coordinated by the AIHW. The ABS data is sourced from state and territory Registries of Births, Deaths and Marriages. This differs from the NPMDC whose data is sourced from health systems, including clinical records. The table below was published in the AIHW Stillbirths and neonatal deaths in Australia report. The table shows that the ABS perinatal dataset is affected by delayed registrations which results in an under count of perinatal deaths, especially those of stillbirths. Caution should be taken when interpreting these data.

For perinatal data output in the Causes of Death, Australia, 2013 publication, the ABS began a review of its method of coding perinatal deaths, which resulted in an interim change to how this data was output. One significant change was that neonatal deaths were not assigned an underlying cause of death when output in tables of all ages, as had previously occurred. (Details of this change can be found in the Changes to Perinatal Death Coding Technical Note in Causes of Death, Australia, 2013 (cat. no. 3303.0)). Further review and consultation has now been undertaken with the national and international coding community, and has resulted in the ABS applying a new method of coding perinatal deaths. The new method creates a sequence of causes on a Medical Certificate of Cause of Perinatal Death which allows for an underlying cause of death to be assigned to a neonatal death. This aligns the output for neonatal deaths to deaths of the general population which are certified using the Medical Certificate of Cause of Death. The change in coding method reinstates the condition arising in the mother being assigned as an underlying cause of death. This method has been applied to the 2014 data onwards, and has also been applied retrospectively to the 2013 neonatal data that is output in tables of all ages in this publication, thus enabling a consistent time-series. Please see the Changes to Perinatal Death Coding Technical Note in Causes of Death, Australia, 2014 (cat. no. 3303.0) for further details.

From the 2013 reference year onwards, process changes have led to a reduction in the number of both stillbirths and neonatal deaths where a 'main condition in mother' was recorded, compared to previous years. This has led to a reduction in the number of records assigned within the code block P00-P04: Fetus and newborn affected by maternal factors and by complications of pregnancy, labour and delivery, as main condition in the mother. These changes will affect data output in the Perinatal data cube of this publication only.

Doctor certified neonatal deaths with no causes of death information are coded to Conditions originating in the perinatal period, unspecified (P969). As these deaths have been certified by a doctor, the assumption is made that the neonate died of natural causes. Where a neonatal death is referred to a coroner, but no causes of death information is available, these deaths are coded to Other ill-defined and unspecified causes of mortality (R99). As a reportable death, it cannot be determined whether the neonate died of natural or external causes, in the absence of further information.

The count of fetal deaths in scope for the World Health Organization (WHO) definition of perinatal deaths differs to those previously published for 2012 and 2015. This is due to an enhancement to birth weight and gestation information, which resulted in some deaths no longer meeting the World Health Organization definition of a fetal death (that is, a gestational age of at least 22 weeks or weighing at least 500 grams). For 2012, there are two fewer fetal deaths than previously published (1 male and 1 female). For 2015, there are 38 fewer fetal deaths than previously published (18 males, 19 females, 1 death where sex was not specified). Some corresponding death rates have also been affected. Table 14.21 in the Perinatal data cube presents fetal and neonatal data according to the WHO scope. No other tables in the Perinatal data cube are affected by these changes.

Live births and the number of fetal deaths are used as the denominator in the calculation of mortality rates for perinatal deaths. See the 'Data Used in Calculating Death Rates' Appendix for details of the number of live births registered which have been used to calculate the fetal, neonatal and perinatal death rates shown in this publication. This Appendix also provides data on fetal deaths used in the calculation of fetal and perinatal death rates. These also enable further rates to be calculated.

In 2019 an issue was identified with the derivation of the Aboriginal and Torres Strait Islander origin for fetal deaths registered in South Australia. As a consequence, there was an undercount of Aboriginal and Torres Strait Islander fetal deaths in South Australia in ABS outputs over a number of years. The ABS worked with the SA RBDM to revise the Aboriginal and Torres Strait Islander origin of all fetal deaths for the years 2014 to 2018. Data for these years presented in Tables 19 and 20 of the Perinatal data cube in this publication was revised in the 2019 issue. 

There are a very small number of stillbirth (fetal deaths) registrations provided to the ABS each year where the sex of the infant has not  been specified as male or female. This can be due to administrative processes where the sex of the stillbirth has not been supplied to the ABS. Additionally, in a small number of births a clinical determination of sex may not be able to be clearly determined. This may be due to a number of reasons and may include extreme prematurity or some congenital conditions. Where the sex of an infant has not been specified for a stillbirth, these deaths are included in total person counts only for tabulations by fetal deaths and all perinatal deaths (both fetal and neonatal deaths). There were 19 stillbirths registered in 2020 where the sex of the infant was not specified.

1. Deaths that are referred to a coroner can take time to be fully investigated. To account for this, the ABS has implemented a revisions process for those deaths where coronial investigations remained open at the time a preliminary cause of death was assigned. Data are deemed preliminary when first published, revised when published the following year and final when published after a second year. This technical note focusses specifically on final data for 2018 causes of death.
2. The revisions process has been applied to all reference periods from 2006 onwards. Revisions are one of two measures implemented to enable timely data to be released on coroner-certified deaths (see 'Revisions process' under the Data quality section of methodology for further information). The second measure, referred to as 'open coding', ensures that all available documentation is taken into account when assigning a cause of death to coronial cases that are yet to be finalised. The combination of these two measures, along with ongoing enhancements in the timeliness and completeness of documentation available on the National Coronial Information System (NCIS), have resulted in significant improvements to the quality of preliminary Causes of Death data. 
3. There are three main improvements to the Causes of Death data which are gained through the revisions process:

• For deaths from natural causes a more specified condition may be identified. For example, a death may be coded to a condition such as Heart disease, unspecified (I51.9) at preliminary coding, but with the later addition of an autopsy report, an underlying ischaemic heart condition could be identified; 
• For deaths from external causes (accidents, assaults and suicides) more information might be provided on mechanism. For example, a death coded to an unspecified accident with a fracture of hip, may later be found to have been caused by a fall down steps;
• External causes may also have the intent of death updated through revisions. For example, a drug overdose where the intent of death was not determined at preliminary coding, may be updated to an intentional (i.e. suicide) drug overdose when a coronial finding has been made.

4. Included in the scope of revisions are 2018 coroner-certified reference year records with an open case status, those which have closed since the last revisions cycle, those coded to an unspecified cause of death, or records where there has been additional information added to NCIS since last coded. Some doctor-certified deaths may also be in scope for revisions. Records in the 2018 reference year include:

• deaths registered in, and received by the ABS, in 2018;
• deaths registered in the 2018 and received by the ABS in the first quarter of 2019; and
• deaths registered in the years prior to 2018 but not received by ABS until 2018 or the first quarter of 2019, provided that these records have not been included in any statistics from earlier periods.

5. In the 2019 reference period an additional 2,812 registered Victorian deaths were identified as not being previously provided to the ABS. Of those additional deaths, 57.0% (1,603) were registered in 2018. While these 1,603 death registrations are in scope for the 2019 revisions process (see Technical note: Victorian additional registrations and time series adjustment in the Causes of Death, Australia, 2019 publication for more information), deaths due to suicide, accidental drug poisoning and assault are included in 2018 tabulations to enable consistency of time series.
6. In 2022 the ABS received updates to the causes of death for some doctor-certified neonatal deaths registered in New South Wales between 2018-2020. These updates meant that neonatal deaths with an unspecified underlying cause of death (P969) were able to be assigned to a more specified underlying cause. These updates are presented in this technical note and the revisions data cube 15 in this publication.
7. In the 2017 reference period, the ABS piloted the coding of information on psychosocial risk factors relating to coroner-referred deaths in Australia. This work has since been extended through a collaboration between the ABS, the Australian Institute of Health and Welfare and the Department of Health as part of the Suicide and Self-Harm Monitoring Project. Data on psychosocial risk factors are now routinely captured as part of the national mortality dataset and are considered in scope for revisions, alongside other information on associated causes of death.

For further information surrounding scope of cause of death statistics, see Scope and coverage in the Methodology section of this publication.

8. Until the 2014 reference period, the ABS released the annual Causes of Death dataset 15 months after the end of each reference period (i.e. data for the 2014 reference period was published in March 2016). The 2015 release of Causes of Death, Australia was released 6 months earlier, representing a significant change in processing of the national mortality dataset. 
9. Bringing forward the release of Causes of Death data meant that preliminary coding of coroner-certified deaths occurred approximately 6 months earlier than in previous years. Given that the timeliness of report availability on the NCIS is critical to the ABS's ability to assign specific cause of death codes, considerable analysis was undertaken to ensure the preliminary dataset would be of sufficient quality to be fit for purpose. See Technical Note 1 A More Timely Annual Collection: Changes to ABS Processes in the 2015 publication.
10. The earlier release of data resulted in a higher number of deaths assigned to R99 at preliminary coding. Subsequently, since 2015 the revisions process has seen a larger proportional decrease in deaths coded to the Symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (Symptoms and signs) (R00-R99) chapter. The 27.6% decrease in this chapter for 2018 is in line with the 2015-2017 reference years. The table below shows the impact of this changed revisions process at the ICD-10 chapter level.

11. The table below provides the counts of deaths by ICD-10 chapter for the 2018 reference period across the revisions process. Revisions are most likely to result in decreases in the number of deaths assigned to Symptoms and signs (R00-R99) with corresponding increases in other chapters.
12. Deaths which are originally coded to the Symptoms and signs (R00-R99) chapter can be reassigned to specific natural or external causes of death. The majority of those reassigned are subsequently found to be deaths from natural causes (76.7%), with Diseases of the circulatory system (I00-I99) being the most common natural cause chapter for deaths to be reassigned to. Of those reassigned from Symptoms and signs (R00-R99) chapter to external causes of death: 19 were due to Falls (W00-W19); 10 were deaths due to Intentional self-harm (suicide) (X60-X84, Y870); and 80 were due to Accidental drug poisoning (X40-X44). 

13. The purpose of the revisions process is to improve data quality. Enhancements to underlying cause of death data quality may include updates to either mechanism or intent or identifying an underlying cause where not previously possible. While the revisions process has a minimal impact at the chapter level (with the exception of R00-R99), data improvements become more apparent when considering movements within individual chapters.
14. The table below shows data for coroner-certified deaths only at the sub-chapter level. There were key data improvements for specification of mechanism for external causes of deaths over the 2018 revisions period. There were 273 deaths where a specified intent was coded but mechanism was unspecified at preliminary coding. Through the revisions process a mechanism was identified for 173 of these deaths. The majority of these records did not change across intent types. For example, a death due to suicide where the mechanism was unspecified at preliminary coding (Intentional self-harm by unspecified means (X84)) may be reassigned to a suicidal drowning (Intentional self-harm by drowning (X71)) during the revisions process when an autopsy becomes available for analysis.  
15. The table below shows that for deaths which are certified by a coroner, the reduction in the number of cases assigned to lll-defined and unspecified causes of mortality (R99) decreased by 49.5% over the full revisions process. 

16. The table below shows changes at the sub-chapter level for the 2018 reference period, with a focus on the External causes of morbidity and mortality (V01-Y98) chapter. Notable increases in deaths due to external causes over the full revisions process include: 

• Accidental drug poisoning (X40-X44) increased by 164 deaths. 40.0% of the deaths reassigned to an Accidental drug poisoning (X40-X44) were originally assigned to Ill-defined causes of mortality (R99). Drug-induced deaths require intensive investigations to accurately determine the cause and manner in which the death occurred. Over time, as investigations are finalised, more information on the NCIS becomes available allowing these deaths to be reassigned to Accidental drug poisonings (X40-X44).
• Intentional self-harm (X60-X84, Y870) increased by 67 deaths. The majority of Intentional self-harm (X60-X84, Y870) deaths reassigned over the revisions process were originally assigned to deaths from Undetermined intent (Y10-Y34) , Accidental drug poisoning (X40-X44), Exposure to unspecified factor (X59) or Ill-defined causes of mortality (R99).
• Specifically, Intentional self-harm by mechanism of drug poisoning (X60-X64) increased by 33 deaths. A large number of  Intentional self-harm by mechanism of drug poisoning (X60-X64) were reassigned due to updated intent information becoming available (especially with the addition of the final coronial finding). The highest number of Intentional self-harm by mechanism of drug poisoning (X60-X64) were reassigned from Accidental drug poisoning (X40-X44).
• Pedestrian injured in transport accident (V01-V09) and Car occupant injured in transport accident  (V40-V49) increased by 11 and 15 deaths respectively. The majority of these deaths were reassigned as more information surrounding the circumstances and intent of the death became available. Most deaths were reassigned from Exposure to unspecified factor (X59) and Crashing of motor vehicle, undetermined intent (Y32).

17. Various improvements to the availability and timeliness of national mortality information have been undertaken over several years. One major improvement undertaken by the NCIS is the more timely upload of reports and information for open coroner cases. This information can then be used at an earlier point by the ABS to improve the quality of open coding for coroner certified records. Earlier availability of reports can reduce the number of deaths from Ill-defined causes of mortality (R99) and Event of undetermined intent (Y10-Y34) present in the dataset at preliminary coding. The improved timeliness in report attachment on the NCIS was a key factor in enabling the ABS to bring forward the publication of annual causes of death data. 
18. There are some specific causes of death that may be more impacted by the changed revisions process. These include Accidental drug poisoning (X40-X44), Intentional self-harm by mechanism of drug poisoning (X60-X64) and Sudden Infant Death Syndrome (SIDS) (R95). Deaths from these causes require intensive investigations to accurately determine the cause and manner in which the death occurred. Therefore some key reports may not be available on the NCIS when preliminary coding of these deaths occur. These deaths are particularly sensitive to the revisions process in that more detailed information regarding the context of the death is often gained over time as information from investigations becomes available on the NCIS. 

19. Over the revisions process there was an increase of 161 deaths due to drug poisoning (includes all intents: Accidental (X40-X44), Intentional (X60-X64), Assault (X85) and Undetermined (Y10-Y14)). Accidental drug poisoning (X40-X44) contributed the largest increase across intent types for drug poisonings over the 2018 revisions process, accounting for 83.2% of the increase. 
20. The process for determining that a death was caused by Accidental drug poisoning (X40-X44) is complex as multiple factors such as drug type, intent and presence of pre-existing natural disease need to be considered. Of the deaths reassigned to an Accidental drug poisoning (X40-X44), 40.0% were initially coded to Ill-defined causes of mortality (R99). These deaths typically did not have toxicology and/or pathology reports available on the NCIS at the time of preliminary coding. A further 22.5% of those reassigned to this category were initially coded to Undetermined drug poisoning (Y10-Y14). 
21. Determining deaths from Intentional self-harm by mechanism of drug poisoning (X60-X64) is similarly complex. Of the 33 deaths that were reassigned to an Intentional self-harm by mechanism of drug poisoning (X60-X64):

• 30.2% were coded at preliminary as Accidental drug poisoning (X40-X44).
• 18.9% were initially coded to Intentional self-harm by unspecified means (X84). Over time, as investigations are finalised, more information on the NCIS becomes available regarding mechanism and circumstances surrounding the death, which allows for more specific coding.
• 15.1% of deaths were initially coded to Undetermined drug poisoning (Y10-Y14).

22. The revisions process has traditionally focussed on improving specificity of the underlying cause of death. Timeliness of NCIS report attachment means preliminary underlying cause coding has improved over time, and less changes to underlying causes occur between revision iterations. As a result, the majority of changes that occur in the revisions process are additions to the associated cause dataset. Associated causes include the type of injuries sustained by a deceased person, drug type in a drug-induced death (e.g. heroin, cannabis), chronic disease (e.g. cancer), mental and behavioural disorders (e.g. depression, anxiety) and psychosocial risk factors. Associated cause statistics are used extensively in policy formulation. Revisions to associated causes typically focus on enhancements for three key areas - drug specification in drug-induced deaths and mental and behavioural disorders and psychosocial factors implicated in deaths from external causes.

23. There are multiple complex factors which need to be considered when a death is certified as a drug poisoning. The timing between the death and toxicology testing can influence the levels and types of drugs detected, making it difficult to determine the true level of a drug at the time of death. Individual tolerance levels may also vary considerably depending on multiple factors, including sex, body mass and a person’s previous exposure to a drug. Consideration of contextual factors around the death must also be considered such as pre-existing natural disease and reports from friends and families regarding the circumstances surrounding death. For these reasons, the certification of a death as a drug poisoning can take significant time to complete, making these deaths particularly sensitive to the revisions process.
24. Policies directed at reducing drug poisoning deaths employ a variety of strategies depending on drug type. Information regarding the type of drug(s) in a drug poisoning can often depend on the availability of an autopsy, toxicology or coronial finding report. When these reports are not available, the drug type is unknown and coded to Other and unspecified drugs, medicaments and biological substances (Unspecified drug) (T509). Importantly, deaths coded with an Unspecified drug (T509) are still counted as a drug poisoning death at preliminary output, but they may be enhanced with more specific information about drug type via the revisions process. 
25. From preliminary to final, the number of drug poisonings in 2018 where drug type was not specified (T509) decreased from 129 to 10. As a result there was an increase in the number of specified drug types (see table below) with Benzodiazepines (T424) recording the largest increase (159 mentions) when analysed by single drug type. This was followed by Other opioids (T402)  (103 mentions) and Psychostimulants with abuse potential (T436) with 77 additional mentions.

26. Associated causes of death can provide important contextual information for deaths due to Intentional self-harm (X60-X84, Y870). At preliminary coding, almost 88% of suicides in 2018 had associated causes, including psychosocial risk factors, mentioned as contributory factors to death. Through the revisions process, this proportion increased to almost 93%. The table below shows the most common associated causes of death added over the revisions process as they relate to Intentional self-harm (X60-X84, Y870). 

• Chronic substance use disorders were identified as an associated cause in an additional 104 deaths due to suicide over the revisions period;
• Mood disorders (including depression) were the most common associated cause in deaths by suicide and were mentioned in an additional 99 deaths due to suicide over the revisions period;
• Problems in spousal relationship circumstances was the most common psychosocial risk factor in deaths due to suicide, and was also the psychosocial risk factor which increased the most over the revisions period.

27. Associated causes of death may also provide critical insights into deaths due to Accidental drug poisoning (X40-X44). The table below shows the most common associated causes of death added over the revisions process as they relate to Accidental drug poisoning (X40-X44). 

• Chronic substance use disorders were identified as an associated cause of death in an additional 147 accidental drug poisoning deaths over the revisions process;
• Mood disorders (F30-F39) were identified as an associated factor in an additional 88 deaths;
• Personal history of self-harm (Z915) was the most commonly mentioned psychosocial risk factor associated with drug overdoses, as well as increased by the largest number from preliminary to final.

1. Deaths that are referred to a coroner can take time to be fully investigated. To account for this, the ABS has implemented a revisions process for those deaths where coronial investigations remained open at the time a preliminary cause of death was assigned. Data are deemed preliminary when first published, revised when published the following year and final when published after a second year. This technical note focusses specifically on revised cause of death data for 2019 deaths.
2. The revisions process has been applied to all reference periods from 2006 onwards. Revisions are one of two measures implemented to enable timely data to be released on coroner-certified deaths (see 'Revisions process' under the Data quality section of methodology for further information). The second measure, referred to as 'open coding', ensures that all available documentation is taken into account when assigning a cause of death to coronial cases that are yet to be finalised. The combination of these two measures, along with ongoing enhancements in the timeliness and completeness of documentation available on the National Coronial Information System (NCIS), have resulted in significant improvements to the quality of preliminary Causes of Death data. 
3. There are three main improvements to the Causes of Death data which are gained through the revisions process: 

• For deaths from natural causes a more specified condition may be identified. For example, a death may be coded to a condition such as an unspecified heart disease at preliminary coding, but with the later addition of an autopsy report, coronary artery disease could be identified;
• For deaths from external causes (accidents, assaults and suicides) more information might be provided on mechanism. For example, a death coded to an unspecified accident with a fracture of hip, may later be found to have been caused by a fall down steps;
• External causes may also have the intent of death updated through revisions. For example, a drug overdose where the intent of death was not determined at preliminary coding, may be updated to an Intentional self-harm by mechanism of drug poisoning when a coronial finding has been made.

4. Included in the scope of revisions are 2019 coroner-certified reference year records with an open case status, those which have closed since the last revisions cycle, or those coded to an unspecified cause of death. Some doctor-certified deaths may also be in scope for revisions. Records in the 2019 reference year include:

• deaths registered in, and received by the ABS, in 2019;
• deaths registered in the 2019 and received by the ABS in the first quarter of 2020; and
• deaths registered in the years prior to 2019 but not received by ABS until 2019 or the first quarter of 2020, provided that these records have not been included in any statistics from earlier periods.

5. In the 2019 reference period an additional 2,812 registered Victorian deaths were identified as not being previously provided to the ABS. Of those additional deaths, 40.4% were registered in 2017 and 57.0% were registered in 2018.  These death registrations are in scope for the 2019 revisions process (see Technical note: Victorian additional registrations and time series adjustment in the Causes of Death, Australia, 2019 publication for more information) and deaths due to suicide, accidental drug poisoning and assault are included in 2017 and 2018 tabulations to enable consistency of time series.
6. In 2022 the ABS received updates to the causes of death for some doctor-certified neonatal deaths registered in New South Wales between 2018-2020. These updates meant that neonatal deaths with an unspecified underlying cause of death (P969) were able to be assigned to a more specified underlying cause. These updates are presented in this technical note and the revisions data cube 16 in this publication.
7. In the 2017 reference period, the ABS piloted the coding of information on psychosocial risk factors relating to coroner-referred deaths in Australia. This work has since been extended through a collaboration between the ABS, the Australian Institute of Health and Welfare and the Department of Health as part of the Suicide and Self-Harm Monitoring Project. Data on psychosocial risk factors are now routinely captured as part of the national mortality dataset and are considered in scope for revisions, alongside other information on associated causes of death.

For further information surrounding scope of cause of death statistics, see Scope and coverage in the Methodology section of this publication.

8. Until the 2014 reference period, the ABS released the annual Causes of Death dataset 15 months after the end of each reference period (i.e. data for the 2014 reference period was published in March 2016). The 2015 release of Causes of Death, Australia was released 6 months earlier, representing a significant change in processing of the national mortality dataset. 
9. Bringing forward the release of Causes of Death data meant that preliminary coding of coroner-certified deaths occurred approximately 6 months earlier than in previous years. Given that the timeliness of report availability on the NCIS is critical to the ABS's ability to assign specific cause of death codes, considerable analysis was undertaken to ensure the preliminary dataset would be of sufficient quality to be fit for purpose. See Technical Note 1 A More Timely Annual Collection: Changes to ABS Processes in the 2015 publication.
10. The earlier release of data resulted in a higher number of deaths assigned to R99 at preliminary coding. Subsequently, since 2015 the revisions process has seen a larger proportional decrease in deaths coded to the Symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (Symptoms and signs) (R00-R99) chapter. The 19.8% decrease in this chapter for 2019 is in line with the 2015-2018 reference years. The table below shows the impact of this changed revisions process at the ICD-10 chapter level.

11. The table below provides the counts of deaths by ICD-10 chapter for the 2019 reference period from preliminary to revised. Revisions are most likely to result in decreases in the number of deaths assigned to the Symptoms and signs (R00-R99) chapter with corresponding increases in other chapters.  
12. Deaths which are originally coded to the Symptoms and signs (R00-R99) chapter can be reassigned to specific natural or external causes of death. The majority of deaths reassigned from Symptoms and signs (R00-R99) are subsequently found to be deaths from natural causes (78.2%) with Diseases of the circulatory system (I00-I99) being the most common natural cause. Of those reassigned to external causes of death, 61 were found to be accidental drug deaths (X40-X44).
     

13. The purpose of the revisions process is to improve data quality. Enhancements to underlying cause data quality may include improved understanding of either mechanism or intent or identifying an underlying cause where not previously possible. While the revisions process has a minimal impact on statistical output at the chapter level of the ICD-10 (with the exception of R00-R99), data improvements become more apparent when considering movements within individual chapters.
14. The table below shows data for coroner-certified deaths only at the sub-chapter level. There were data improvements for specification of mechanism for external causes of deaths over the 2019 revisions period. There were 223 deaths where a specified intent was coded but mechanism was unspecified at preliminary coding. Through the revisions process a mechanism was identified for 130 (55.8%) of these deaths. The majority of these records did not change across intent types. For example, a death due to suicide where the mechanism was unspecified at preliminary coding (Intentional self-harm by unspecified means (X84)) may be reassigned to a suicidal drowning (Intentional self-harm by drowning (X71)) during the revisions process when an autopsy becomes available for analysis.
15. The table below shows that for deaths which are certified by a coroner, the reduction in the number of cases assigned to lll-defined and unspecified causes of mortality (R99) decreased by 35.1% from preliminary to revised.

16. The table below provides information on changes at the sub-chapter level for the 2019 reference period, with a focus on the External causes of morbidity and mortality (V01-Y98) chapter. Deaths due to external causes often require investigations to accurately determine the cause, manner and intent of the death, and are often subject to change across the revisions cycles . As investigations are finalised, more information on the NCIS becomes available and coders can apply this information to further specify or update causes of death. 
17. Drug poisoning and intentional self-harm deaths are particularly susceptible to intent and mechanism changes over the revisions cycles. This is evidenced by the changes seen preliminary to revised, including:

• An increase of 86 deaths by Accidental drug poisoning (X40-X44) . Approximately half of those deaths were originally assigned to Ill-defined causes of mortality (R99).
• An increase of 40 deaths by Intentional self-harm (X60-X84, Y87.0).  Over half of these deaths were reassigned from Undetermined intent (Y10-Y34). 
• An increase of 19 deaths by Intentional self-harm by mechanism of drug poisoning (X60-X64). Approximately 30% of these deaths were reassigned from Intentional self-harm by unspecified mechanism (X84), and another 25% from Undetermined drug poisoning (Y10-Y14).

18. Various improvements to the availability and timeliness of national mortality information have been undertaken over several years. One major improvement undertaken by the NCIS is the more timely upload of reports and information for open coroner cases. This information can then be used at an earlier point by the ABS to improve the quality of open coding for coroner certified records. Earlier availability of reports can reduce the number of deaths from Ill-defined causes of mortality (R99) and Event of undetermined intent (Y10-Y34) present in the dataset at preliminary coding. The improved timeliness in report attachment on the NCIS was a key factor in enabling the ABS to bring forward the publication of annual causes of death data. 
19. There are some specific causes of death that may be more impacted by the changed revisions process. These include Accidental drug poisoning (X40-X44), Intentional self-harm by mechanism of drug poisoning (X60-X64) and Sudden Infant Death Syndrome (SIDS) (R95). Deaths from these causes require intensive investigations to accurately determine the cause and manner in which the death occurred. Therefore some key reports may not be available on the NCIS when preliminary coding of these deaths occurs. These deaths are particularly sensitive to the revisions process, in that more detailed information regarding the context of the death is often gained through revisions. 

20. From preliminary to revised there was an increase of 102 deaths due to drug poisoning (includes all intents: Accidental (X40-X44), Intentional (X60-X64), Assault (X85) and Undetermined (Y10-Y14)). Accidental drug poisonings (X40-X44) contributed the largest increase across intent types for drug poisonings for 2019, with an increase of 86 deaths.
21. The process for determining that a death was caused by an Accidental drug poisoning (X40-X44) is complex, as multiple factors such as drug type, intent and presence of pre-existing natural disease need to be considered. Of the deaths reassigned to Accidental drug poisoning (X40-X44) 50.4% were initially coded to Other ill-defined and unspecified causes of mortality (R99), while 19.0% were initially coded to Undetermined drug death (Y10-Y14). These deaths typically had only an initial police report available at preliminary coding, where circumstances surrounding death can be unclear and often similar to deaths from natural causes.
22. Determining deaths from Intentional self-harm by mechanism of drug poisoning (X60-X64) is similarly complex. Of the deaths that were reassigned to an Intentional self-harm by mechanism of drug poisoning (X60-X64):

• Almost 40% were coded at preliminary as suicide, but by a mechanism other than drug poisoning. With additional reports available the mechanism of death was updated.  
• Approximately a quarter were initially coded to an Undetermined drug death (Y10-Y34).
• A further 18.6% of these deaths coded to an Accidental drug poisoning (X40-X44) at preliminary. These deaths often only have police reports available on NCIS at the time of preliminary coding and may not provide information on mechanism and/or intent. 

23. The revisions process has traditionally focused on improving specificity of the underlying cause of death. Timeliness of NCIS report attachment means preliminary underlying cause coding has improved over time, and less changes to underlying causes occur between revision iterations. As a result, the majority of changes that occur in the revisions process are additions to the associated cause dataset. Associated causes include the type of injuries sustained by a deceased person, drug type in a drug-induced death (e.g. heroin, cannabis), chronic disease (e.g. cancer), mental and behavioural disorders (e.g. depression, anxiety) and psychosocial risk factors. Associated cause statistics are used extensively in policy formulation. Revisions to associated causes typically focus on enhancements for three key areas - drug specification in drug-induced deaths and mental and behavioural disorders and psychosocial factors implicated in deaths from external causes.

24. There are multiple complex factors which need to be considered when a death is certified as drug-induced. The timing between the death and toxicology testing can influence the levels and types of drugs detected, making it difficult to determine the true level of a drug at the time of death. Individual tolerance levels may also vary considerably depending on multiple factors, including sex, body mass and a person’s previous exposure to a drug. Consideration of contextual factors around the death must also be considered such as pre-existing natural disease and reports from informants (e.g. friends and families) regarding the circumstances surrounding death. For these reasons, the certification of a death as being drug-induced can take significant time to complete, making these deaths particularly sensitive to the revisions process.
25. Policies directed at reducing deaths due to drug poisoning employ a variety of strategies depending on drug type. Information regarding the type of drug(s) in a drug poisoning can often depend on the availability of an autopsy, toxicology or coronial finding report. When these reports are not available, the drug type is unknown and coded to Other and unspecified drugs, medicaments and biological substances (Unspecified drug) (T509). Importantly, deaths coded with an Unspecified drug (T509) are still counted as a drug-induced death at preliminary output, but they may be enhanced with more specific information about drug type via the revisions process. 
26. From preliminary to revised, the number of drug-induced deaths in 2019 where drug type was not specified (Unspecified drug (T509)) decreased from 87 to 14. As a result, there was an increase in the number of specified drug types (see table below), with Benzodiazepines (T424) recording the largest increase (110 additional mentions) when analysed by single drug type. This was followed by Other opioids (T402) (62 additional mentions) and Tricyclic and tetracyclic antidepressants (T430) (47 additional mentions).

27. Associated causes of death can provide important contextual information for deaths due to Intentional self-harm (X60-X84, Y870). At preliminary coding, approximately 88% of suicides in 2019 had associated causes, including chronic conditions and psychosocial risk factors, mentioned as contributory factors to death. Through revisions, this proportion increased to almost 93%. The table below shows the most common associated causes of death added over the revisions process as they relate to Intentional self-harm (X60-X84, Y870). For suicides, mental and behavioural disorders (F00-F99) and Psychosocial risk factors (Z00-Z99) are some of the most common associated cause additions across the revisions process, with:

• Mood disorders (F30-F39), including depression and bipolar affective disorder, were identified as being a factor in an additional 137 deaths;
• Previous suicide ideation was a factor in an additional 130 deaths;
• An additional 113 deaths identifying a chronic substance use disorder , which include abuse of, and dependency, on substances as an associated cause; and
• Personal history of self-harm and Problems in relationships (Z630, Z635), which includes relationship issues and separation, were identified as an associated causes in an additional 118 and 89 deaths due to suicide.

28. Associated causes may also provide critical insight into deaths due to Accidental drug poisoning (X40-X44). The table below shows the most common associated causes of death added over the revisions process as they relate to Accidental drug poisonings (X40-X44).

• 116 additional deaths where a Mental and behavioural disorders due to psychoactive substance use (F10-F19), such as addiction or chronic substance misuse, was identified; 
• Mood disorders (F30-F39) were identified as a contributing factor in an additional 71 deaths; and
• 60 additional deaths where Anxiety and stress-related disorders (F40-F49) were identified as a factor; 
• Problems related to legal circumstances (Z650-Z654) were the most commonly mentioned psychosocial risk factors associated with drug overdoses, as well as increasing by the largest number from preliminary to revised.

1. As part of the ABS's revisions process for Causes of Death, the ABS updates causes for coroner-certified deaths at 12 and 24 months after initial processing, to reflect the latest available information. Revisions have now been applied to 2018 and 2019 data. As coronial investigations regarding deaths due to suspected suicide can be extensive, it is a cause of death which may be more heavily impacted by revisions. It is important from a public health perspective to have accurate counts of suicides. As such, this technical note focusses on how the revisions process has changed suicide counts in 2018 and 2019. 
2. Over time there has been a reduction in the number of deaths that are reassigned to suicide through the revisions process. In 2006 and 2007, the first years for which revisions were applied, the number of deaths due to suicide increased by 17.7% and 18.5%, respectively. In 2018, the final suicide count was 2.1% higher than the preliminary count. A number of associated causes of death including more specified substances and risk factors such as mental health conditions, chronic diseases and psychosocial factors have also been updated during the revisions period. See Technical notes on revisions of 2018 and 2019 data (above) for further information. Several factors have impacted on the increased quality of preliminary data, including enhanced coding practices, enabling greater use of documents available on the National Coronial Information System (NCIS) and more timely report attachment.
3. There were 180 suicides that were registered in Victoria in 2017 (88 suicides) and 2018 (92 suicides) but not supplied to the ABS until 2019. The additional registrations are in scope for the 2019 reference period, and have been revised. The revised counts for these deaths due to suicide that were registered in 2017 and 2018 are published in their corresponding registration years in the tables below. See Technical note: Causes of death revisions, Victorian adjusted records for information on revisions updates to the additional registrations. 

4. The final number of deaths due to suicide recorded for 2018 is 3,205, a net increase of  67 deaths (2.1%) from the preliminary count of 3,138. There was an increase of 54 suicides over the first revision period and an increase of 13 suicides in the second revision period. 
5. Deaths which have been reassigned to suicide through the revisions process were most likely to be initially coded to an Event of undetermined intent (Y10-Y34) (45 deaths) or Accidental drug poisoning (X40-X44) (17 deaths). Additionally, of the deaths later identified as suicides through the revisions process: 

• 14 deaths were initially coded to Exposure to unspecified factor causing other and unspecified injury (X599);
• 10 deaths that were initially coded to Other ill-defined and unspecified causes of mortality (R99);
• There were also some minor changes in the recorded mechanism of death associated with additional information becoming available, especially toxicology and pathology reports. 

6. The revised number of suicides in 2019 is 3,358, a net increase of 40 suicide deaths (1.2%) over the first year of the revisions process. Most deaths reassigned to suicide were initially coded to Event of undetermined intent (Y10-Y34) (39 deaths). There were 8 deaths reassigned from Accidental drug poisoning (X40-X44) and 7 from Exposure to unspecified factor (X59). The table below shows the total redistributed suicide counts for Australia at each stage of the revisions process for 2017, 2018 and 2019. Deaths by suicide in 2017 are included in the table as the Adjusted Victorian additional registrations are in scope as part of the 2019 reference year revisions cycle. See Causes of death revisions, Victorian adjusted records below for information on revisions updates to additional registrations.

7. The number and age-standardised death rate of deaths due to intentional self-harm by state and territory from 2011 to 2020 are shown in the tables below. These tables provide an updated time series that includes the revisions for 2018 and 2019 and should now be used in preference to those published in September 2021. A more detailed table which includes revised suicide counts by mechanism (ICD-10 codes X60-X84 and Y87.0) are provided in the Revisions data cube 16 in the Downloads tab of this publication. Further tabulations are available on request. Please contact the National Information and Referral Service on 1300 135 070.

1. During the 2019 revisions cycle, updates were made to 5 records across 2017 and 2018 additional death registrations. Having received additional information on the National Coronial Information System (NCIS), 2 records have been reassigned to underlying causes of death that are not in scope for redistribution (i.e. are no longer an intentional self-harm, accidental drug poisoning, or assault death).
2. For further information on Victorian additional registrations, see Technical note: Victorian additional registrations and time series adjustment in the Causes of Death, Australia, 2019.