Causes of Death, Australia methodology

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

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 2022, 87.8% of deaths were certified by a doctor. The remaining 12.2% were certified by a coroner. There are variations between jurisdictions in relation to the proportion of deaths certified by a coroner, ranging from 6.0% of deaths certified by a coroner and registered in Queensland, to 29.1% of deaths certified by a coroner and registered in the Northern Territory.

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 2022, 97.0% of perinatal deaths were certified by a doctor, with the remaining 3.0% 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). As a voluntary collaboration between the Australian States and Territories and New Zealand, the NCIS is independent of the coronial system and does not form any part of the coronial investigation process. The NCIS enables access to some documents from the coronial investigation, however it is not intended to be a full replica of the coronial brief.

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.

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
• 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 can be identified) 
• stillbirths/fetal deaths (these are included in perinatal death statistics (see Perinatal deaths)). In 2007-2009 these were published separately in Perinatal Deaths, Australia, 2009 (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.

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. In Australia, a death cannot be registered until a burial or cremation has occurred. This requirement can result in delays in the registration of deaths and 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)
• a date on which the registered death is lodged with the ABS and deemed in scope (reference date).

Data can be presented in different ways based on these dates.

Year of registration

For the 2022 Causes of Death publication data is presented by year of registration (based on date of registration). This represents a change from previous years where data was presented by reference year. This change has been applied across all years to enable consistency of time series for comparable analysis. For some years, the number of deaths registered in that year is the same as the number that fall within scope of the reference year, but for other years, the numbers are quite different.

In recent years, there have been occasions where the ABS has received a large number of deaths which were registered in earlier years. These death registrations fell within scope of the reference year in which they were received. Therefore presenting deaths data by reference year is not necessarily representative of mortality patterns in that year and can have a greater impact on specific causes of death. For examples of where the ABS has received late registrations and the impact on mortality patterns, see Technical Note: Victorian additional registrations and time series adjustment and Technical Note: Victorian additional registrations (2013-2016).

Reference year

Prior to 2022, Causes of Death data was presented by reference year (based on reference date). The scope for reference year 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
• 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.

Data for the ABS Deaths, Australia publication will continue to be presented by reference year. Therefore total numbers of deaths for each year in the Causes of Death publication will not necessarily match total numbers of deaths in the Deaths publication. The table below shows the differences in numbers over the last 10 years.

Year of occurrence

Data can also be presented by year of occurrence (based on date of occurrence). Approximately 5% to 8% of deaths occurring in one year are not registered until the following year or later. 

A small number of tables in the Causes of Death publication are published by year of occurrence, ie. Table 11.21 in the '11. Intentional self-harm (suicide)' data cube; all tables in the '14. Causes of Death by year of occurrence' data cube; and Table 15.25 in the '15. Perinatal deaths' data cube.

Information in the Causes of Death and Deaths publications is not comparable with deaths data published in the monthly Provisional Mortality Statistics reports which provides preliminary counts of deaths by date of occurrence.

Causes of Death data by reference year or year of occurrence is available on request.

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 vital statistics published by the ABS would not be available. Additionally, the ABS would like to acknowledge assistance provided by the Coroners Court of New South Wales. 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 editing checks at the individual record and aggregate levels, seeking detailed information from the National Coronial Information System (NCIS), and undertaking a revisions process for open coroner certified deaths.

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 2022 preliminary data, 2021 preliminary revised data and 2020 revised data. For more details of the early preliminary revision of 2021 data refer to Technical Note: Causes of death revisions, 2021 preliminary revision. Data for reference years up to and including 2019 are considered final and no longer subject to the revisions process. Final data for 2020, revised data for 2021, and preliminary revised data for 2022 will be released in early 2024. 

Excess mortality

The number of deaths registered in 2022 (190,939) increased by 19,470 (11.4%) compared to 2021 registrations, with a similar percentage increase across doctor and coroner certified deaths. Since the start of the Omicron wave of COVID-19 in Australia (from January 2022), excess mortality has been recorded for all jurisdictions. For more information, including official excess mortality estimates, refer to the article Measuring Australia’s excess mortality during the COVID-19 pandemic until the first quarter 2023.

Coroner certified deaths data

Deaths that are referred to a coroner can take time to be fully investigated, which subsequently affects the availability of data to the ABS for cause of death coding. Each year, some coroner cases are coded by the ABS before the coronial proceedings are finalised. Coroner 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.

Over recent years, for some jurisdictions, there has been an increasing delay in information flowing between the coroner court and the National Coronial Information Service (NCIS), including uploading autopsy reports, toxicology reports and coronial findings, and updating the closure status. Some jurisdictions are more affected than others. For statistics on case closure and document attachment for each jurisdiction, refer to the Operational Statistics published on the NCIS website.

At the time of coding 2022 data, there was a high proportion of open coroner cases (65.2%), similar to the proportion at the time of preliminary coding of 2021 (67.2%). This is higher than previous years (5-year average for 2015-2019 of 56.2%). This is reflected in the 2022 dataset by a higher proportion of deaths due to Other ill-defined and unspecified causes of mortality (R99). Cases coded to R99 made up 10.7% of the coroner certified deaths dataset in 2022. The proportion in 2021 was 9.8%. This compares with a historical average of 6.3%.

Causes of death data for 2021 would have ordinarily been revised in early 2024. Due to the high number of deaths coded to ill-defined and unspecified conditions, an early revision of 2021 data was conducted during the 2023 causes of death revisions cycle. This revision targeted open cases coded to Other ill-defined and unspecified causes of mortality (R99), Exposure to unspecified factor (X59) and Unspecified event, undetermined intent (Y34), with the aim of enhancing the specificity of the codes applied to these cases by capturing additional coronial information made available since initial coding. Of deaths in scope for the 2021 revisions period, 498 were able to be assigned to more specific causes of death. For more details of this early revision refer to Technical Note: Causes of death revisions, 2021 preliminary revisions.

Based on the success of the preliminary revision of 2021, an early revision of 2022 will be conducted during the upcoming revisions cycle in 2024. Similar to the 2021 exercise, it will target specific codes including Other ill-defined and unspecified causes of mortality (R99, Exposure to unspecified factor causing other and unspecified injury (X59.9), and Event of undetermined intent (Y10-Y34).

Causes of death with a high proportion of coroner certified deaths (e.g., suicide, assault, drug-induced deaths) should be interpreted with caution due to the expectation that this data will change during revisions.

Drug-induced deaths

Drug-induced deaths are those which are directly attributable to drug use. They include deaths due to acute drug toxicity (e.g. overdose) and chronic drug use (e.g. drug-induced cardiac conditions).

On average, 97% of drug-induced deaths are certified by a coroner. 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. 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. 

Numbers of drug-induced deaths for 2021 and 2022 are likely influenced by the higher proportion of open cases for these years. It is expected these numbers will increase when the ABS revisions process is applied. Caution should be used when interpreting drug-induced deaths data until numbers are final.

Victorian additional registrations

As a result of two reconciliation exercises conducted jointly between the ABS and the Victorian Registry of Births Deaths and Marriages (Victorian RBDM), additional historical death registrations have been added to the mortality dataset. This was due to an issue associated with the Registry's previous processing system (replaced in 2019) which resulted in some death registrations not being delivered to the ABS in the year they were registered. 

The first exercise (conducted in the first quarter of 2020) resulted in the identification of an additional 2,812 death registrations from 2017 to 2019 that had not previously been provided to the ABS. Of these, 40.4% were registered in 2017, 57.0% in 2018 and the remainder in 2019 (2.6%). The 2,812 Victorian deaths were in scope of the 2019 reference year and therefore included in 2019 counts of total deaths in both the Deaths, Australia, 2019 and Causes of Death, Australia, 2019 datasets.

Of the 2,739 deaths that were registered in 2017 and 2018 and submitted to the ABS for the 2019 reference year 62.9% were certified by a coroner with the remaining 37.1% certified by a doctor. This 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. See Technical note: Victorian additional registrations and time series adjustments in Causes of Death, Australia, 2019 for detailed information on this issue. 

A subsequent exercise (conducted in the first quarter of 2022) identified a further 1,864 death registrations from 2013 to 2016 that had not previously been provided to the ABS. Of these, 31.7% were registered in 2013, 24.6% in 2014, 7.7% in 2015 and the remainder in 2016 (36.1%). As these deaths occurred more than five years prior to the 2021 reference year, they were not considered to be representative of mortality in 2021 and were excluded from the 2021 reference year counts. In the Deaths, Australia publication these additional registrations are included in tables that are presented by year of occurrence of death only. See Technical note: Victorian additional registrations (2013-2016) for more details on these registrations and how they are reflected in published data. 

For the 2022 publication, these additional Victorian registrations obtained by the ABS during both reconciliation exercises are presented by year of registration. This ensures the number of deaths for a particular year is more representative of the deaths that were registered in that year.

Additionally, as part of the implementation of the new registration system in Victoria in February 2019, there was a change in the way coroner referred deaths are reported to the ABS. Previously there was 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 changed and interim registrations (open cases) have been submitted to the ABS resulting in more timely delivery of death registration information to the ABS.

Updates to Western Australian doctor certified causes of death data 2016 to 2020

An issue was identified with cause of death data for doctor certified deaths registered between 2016-2020 in Western Australia. Information originating from Part II of the Medical Certificate of Cause of Death (MCCD) or Medical Certificate of Cause of Perinatal Death (MCCPD) was not uploaded into the ABS Mortality processing system. The main impact was on the associated causes, both in terms of the capture of conditions listed and the number of causes listed as contributing to death. Updated data was released as part of the Revisions to causes of death release and is reflected in this publication. For more detailed information, refer to Technical note: Updates to doctor certified causes of death data, Western Australia, 2016 to 2020.

Updates to Queensland doctor certified causes of death data 2016 to 2021

An issue was identified with cause of death data for doctor certified deaths registered between 2016-2021 in Queensland. Information originally provided to the ABS in Part II of the Medical Certificate of Cause of Death (MCCD) was moved to Part I of the MCCD when uploaded into the ABS Mortality processing system. As a consequence, some cause information did not align with the original certificate and the change in sequence altered the application of the ICD-10 coding rules when assigning the underlying cause of death. This impacted approximately 300 to 600 records each year, representing less than 2% of doctor certified deaths in Queensland. Updated data was released as part of the Revisions to causes of death release and is reflected in this publication.

Change in reporting of Tasmanian birth registrations

A change in processing has affected the number of births registered in Tasmania in 2022. This change has contributed to a decrease of 529 births (or 8.8%) in Tasmania compared to 2021.

Birth registrations are assigned to a reference year based on their date of registration. Up to the 2022 reference year, a legacy reporting issue meant that Tasmanian births were assigned to a reference year based on the date they were first entered into the registry system (the insertion date), rather than the date on which the registration was finalised (the registration date). From the 2023 reference year, the registration date has been used, aligning reporting for all jurisdictions. As the registration date is generally a few days after the insertion date, 336 births that would previously have been recorded in Tasmania in the 2022 reference year will now appear in 2023. This change accounts for nearly two-thirds (63.5%) of Tasmania's decrease. Had this processing change not been applied, Tasmania's birth decrease would have been 3.2% (or 193 births), which is similar to the national decrease of 3.0%. This change has introduced a break in series in birth statistics for Tasmania. 

All Tasmanian births continue to be registered and reported to the ABS. Detailed births data for 2022 will be released in Births, Australia, 2022.

Impacts of COVID-19 pandemic lockdowns

In 2020, 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. 

Victoria recorded a decrease in birth registrations in 2022 compared to 2021 (down 0.3%). This was much less than the national decrease of 3.0%, and follows a smaller increase in births registered in Victoria in 2021 (2.4%) when nationally births increased by 5.3%. When compared to other jurisdictions, Victoria had a higher proportion of births registered in 2022 that occurred in 2021 (16.4%) and this may have contributed to both the smaller increase in 2021 and the smaller decrease in 2022. Detailed births data for 2022 will be released in Births, Australia, 2022.

Other historical considerations

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 2016 and 2017 there were lower than expected birth 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 birth 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.

The Census and Statistics Act 1905 provides the authority for the ABS to collect statistical information, and requires that statistical output shall not be published or disseminated in a manner that is likely to enable the identification of a particular person or organisation. This requirement may restrict access to data at a very detailed level.

Some 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. Refer to the footnotes for the tables where confidentialisation has been applied.

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.

Customised tables based on the data available in this publication is available through a paid data consultancy. Provide details through a Consultancy Request Form to find out more information. 

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. 

Sex and gender

The 'sex' variable has traditionally been interpreted as reflecting the sex of the deceased, as reported at birth. In recent years, some states and territories have amended their jurisdictional-based Births, Deaths and Marriages legislation to allow for gender identity to be reported or updated on birth and death registrations. For a death registration, the change in legislation means that a person’s gender identity may be recorded. The terms 'sex' and 'gender' are interrelated and often used interchangeably, however they are two distinct concepts, and a person's sex may differ to their gender identity. Data for 'sex' in this publication may refer to:

• the person's sex reported at birth. This is currently how the vast majority of deaths are captured.
• the person's gender identity.

Data for sex is output in tables as ‘males’ and ‘females’ only. Sex not stated may be included in totals.

With the legislative changes, there are now instances in the data where a person has died from a cause of death that is not traditionally considered to be consistent with their reported sex. For example, prostate cancer may be recorded for a female, or ovarian cancer may be recorded for a male. While the number of such deaths is very small for 2022, they are expected to increase over time.

Aboriginal and Torres Strait Islander origin

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. For details of how the Aboriginal and Torres Strait Islander origin is derived for each state and territory and changes to this derivation over time, refer to the Deaths of Aboriginal and Torres Strait Islander people section.

Statistical geographic areas

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, the usual residence of the deceased is coded to the meshblock level. For further information, refer to the Australian Statistical Geography Standard (ASGS) Edition 3, July 2021 - June 2026. 

Causes of death statistics are presented at the national, state/territory and greater capital city/rest of state levels in this publication. These statistics 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. Usual residence data at the sub-state level for 2001 to 2020 was revised for the 2021 publication to reflect the 2021 version of the ASGS. 

Socio-Economic Indexes for Areas

Socio-Economic Indexes for Areas (SEIFA) is an ABS product that ranks areas in Australia according to relative socio-economic advantage and disadvantage. The indexes are based on information from the five-yearly Census of Population and Housing. 

SEIFA quintiles used in this publication are based on the Index of Relative Socio-economic Disadvantage (IRSD). This index is a general socio-economic index that summarises a range of information about the economic and social conditions of people and households within an area.

A low score indicates relatively greater disadvantage. For example, many households with low income, or many people without qualifications, and many people in low skilled occupations.

A high score indicates a relative lack of disadvantage. For example, few households with low incomes, few people without qualifications, and few people in low skilled occupations. A high score is not an indicator of advantage; rather it is an indicator of the absence of disadvantage. 

SEIFA quintiles represent approximately 20% of the national population, but do not necessarily represent 20% of the population in each state and territory. Disaggregation by SEIFA is based on a person’s usual residence aligned to geography based on 2021 ASGS Remoteness Area structure. Correspondence files are sourced from the ASGS: Main Structure and Greater Capital City Statistical Areas. Data presented by SEIFA has been revised for 2001 to 2021 to reflect the 2021 version of the ASGS.

Country of birth

The country of birth of the deceased is coded and presented based on the Standard Australian Classification of Countries (SACC). Deaths coded according to the SACC reflect the country of birth of the deceased, as opposed to ancestry. 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
• 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 and access to versions of the ICD refer to WHO International Classification of Diseases (ICD).

Updates to the ICD

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 2013-2022 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 2022 reference year causes of death data presented in this publication was coded using version 5.8.0 of Iris software which applied the WHO ICD-10 updates (2020 version). For coding of 2021 data, the dictionary was updated to reflect new codes added including for vaccine deaths and long COVID-19. 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 technical notes ABS Implementation of the Iris Software: Understanding Coding and Process Improvements  in the Causes of Death, Australia, 2013 publication and Updates to Iris coding software: Implementing WHO updates and improvements in coding processes in the Causes of Death, Australia, 2018 publication.

Coding of COVID-19

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. A death directly due to COVID-19 is defined by the WHO as a death resulting from a clinically compatible illness, in a probable or confirmed COVID-19 case, unless there is a clear alternative cause of death that cannot be related to COVID disease (e.g. trauma). There should be no period of complete recovery from COVID-19 between illness and death. 

In 2021, COVID-19 vaccinations were introduced globally. The World Health Organization subsequently issued the ICD-10 emergency code U12.9 (COVID-19 vaccines causing adverse effects in therapeutic use, unspecified) to capture adverse effects of COVID-19 vaccines in therapeutic use. This code allows COVID-19 vaccine-related deaths to be identified separately from deaths involving adverse reactions to other vaccines and biological substances. 

In summary, the following new emergency codes have been issued by WHO since 2020 in response to the emergence of COVID-19 to be used when coding causes of death for statistical purposes: 

• U07.1 COVID-19 virus identified - This code is used when COVID-19 is confirmed by laboratory testing.
• U07.2 COVID-19 virus not identified - This code is used for suspected or clinical diagnoses of COVID-19 where testing is not completed or inconclusive.
• U08 Personal history of COVID-19 - This code is used when a person has recovered from COVID-19 and no long-term effects have been certified as contributing to an individual’s death and/or COVID-19 is listed on the death certificate but it did not contribute to the death. These deaths are not included in COVID-19 mortality tabulations.
• U09 Post COVID-19 condition - This code is used to link long-term conditions including chronic lung conditions that are the result of the virus. These deaths are included in COVID-19 mortality tabulations as associated causes of death. 
• U10 Multisystem inflammatory syndrome associated with COVID-19 - This code is used to identify people who have died from COVID-19 where the virus has led to a multi-inflammatory response syndrome. 
• U11 Need for immunization against COVID-19 - This code has been assigned to deaths where an incidental mention of a COVID-19 vaccine has been listed on the death certificate. An incidental mention is where the doctor has stated that a person recently received a vaccine but it did not have any contribution to death. 
• U12 COVID-19 vaccines causing adverse effects in therapeutic use - This code allows COVID-19 vaccine-related deaths to be identified separately from deaths involving adverse reactions to other vaccines and biological substances.

A further code ‘Z03.8 Examination for observation and other specified reasons’ can be used to record a negative test result in order to capture this information on the death certificate. These deaths are not tabulated as being due to COVID-19. 

Other significant historical updates

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 four-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 four-digit options to further specify the death:

• X47.0/X67.0/X88.0/Y17.0 carbon monoxide from combustion engine exhaust 
• X47.1/X67.1/X88.1/Y17.2 carbon monoxide from utility gas
• X47.2/X67.2/X88.2/Y17.2 carbon monoxide from other domestic fuels
• X47.3/X67.3/X88.3/Y17.3 carbon monoxide from other sources
• X47.4/X67.4/X88.4/Y17.3 carbon monoxide from unspecified sources 
• X47.8/X67.8/X88.8/Y17.8 other specified gases and vapours 
• X47.9/X67.9/X88.9/Y17.9 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 Official ICD-10 Updates can be found online.

Conditions on the medical certificate of cause of death are coded to the International Classification of Diseases, 10th revision (see Classifications section 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 2013-2022 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 2022 reference year causes of death data presented in this publication was coded using version 5.8.0 of Iris software which applied the WHO ICD-10 updates (2020 version). For coding of 2021 data, the dictionary was updated to reflect new codes added including for vaccine deaths and long COVID-19. 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 technical notes ABS Implementation of the Iris Software: Understanding Coding and Process Improvements in the Causes of Death, Australia, 2013 publication and Updates to Iris coding software: Implementing WHO updates and improvements in coding processes 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 influenced by 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.

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.

See Data Quality – Coroner certified deaths data for further information about quality considerations for coroner certified data.

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. Diseases and injuries which are listed on the death certificate and not selected as the underlying cause are referred to as associated causes of death. The majority of data presented in the data cubes 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. With an ageing population, people are more likely to die with multiple co-morbid conditions, many of which may be listed on the death certificate. The multiple cause of death data can provide more meaningful insights into relationships between diseases and how these may contribute to mortality. This information cannot be obtained from focussing on the underlying cause of death data alone.

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.

The table below provides selected examples of causes of death and their propensity to be reported as an underlying cause of death, compared to an associated cause of death. Numbers presented in the table are averages based on 2022 data.

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 2022 is expected to change as data is subject to the revisions process. See Data Quality – Revisions process for more information about the ABS revisions process.

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 2022 is expected to change as data is subject to the revisions process. See Data Quality – Revisions process for more information about the ABS revisions process.

The source of all cause of death data for the ABS is collected through the civil registration system either by the Medical Certificate of Cause of Death (MCCD) for doctor certified deaths or the pathology report or coronial findings for coroner referred deaths (accessed via the National Coronial Information System). This enables identification of the underlying cause of death and other associated causes and risk factors. Civil-registration-based data is not directly comparable with that released from disease surveillance systems which are designed to release information rapidly on both infections and mortality. Information about mortality sourced from the registration-based system takes longer to receive than information reported through the surveillance system, but it is more comprehensive and can provide important additional insights into deaths from COVID-19. 

COVID-19 vaccine-related deaths

The civil registration system also captures deaths which may be caused by COVID-19 vaccines. The World Health Organization issued the ICD-10 emergency code U12.9 (COVID-19 vaccines causing adverse effects in therapeutic use). This code allows COVID-19 vaccine-related deaths to be identified separately from deaths involving adverse reactions to other vaccines and biological substances.

Independent analysis and interpretation of deaths data by authorities such as the Therapeutic Goods Administration (TGA) is not conveyed to the ABS or reflected in coding outputs. Due to the scope of the ABS deaths collection, data received and published by the ABS may differ from data collected through the TGA's independent investigations into COVID-19 vaccine-related deaths. The ABS and the TGA have communicated and understand that there are differences in how a death may be categorised as being related to a COVID-19 vaccine. These differences may include scope (as described) and the timing of coding and investigations (the TGA regularly updates data in relation to vaccines, whereas the ABS is reporting on coded data at a point in time). The ABS and the TGA will continue to work together to ensure that datasets remain consistent as possible whilst taking into account the known differences in each agency’s reporting scopes.

• There have been 16 deaths in Australia for which the information provided to the ABS indicated that COVID-19 vaccination was the underlying cause of death, 15 of which were registered in 2021.
• Of these, 14 were certified by a coroner and 2 were certified by a doctor.
• The majority of deaths (92.9%) assigned as being due to the COVID-19 vaccine have open coronial cases meaning they are in scope of the ABS revisions process. Additional information will be reviewed by the ABS in relation to these deaths as it is received.
• As of 7 September 2023, the TGA has identified 14 reports where the cause of death was linked to vaccination. Refer to the TGA COVID-19 vaccine safety reports for further details on the TGA’s vaccine safety monitoring process. 

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.

Since 2017, the ABS 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 data cubes 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.

Since 2020, the ABS includes COVID-19 deaths as a WHO leading cause group. COVID-19 deaths include ICD-10 codes U07.1 COVID-19 virus identified, U07.2 COVID-19 virus not identified, and U10.9 Multisystem inflammatory syndrome associated with COVID-19, unspecified.

Deaths coded to Chapter XVIII: Symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R99) are not included in tabulations of leading causes due to the unspecified nature of these causes. Many deaths coded to this chapter are likely to be affected by revisions, and hence recoded to more specific causes of death as they progress through the revisions process. An exception to this is Ill-defined and unknown causes of mortality (R95-R99), which is included in the analysis for deaths of those under the age of one year, as Sudden Infant Death Syndrome (R95) and Sudden Unexpected Death in Infancy (R99) is included in this cause grouping. A further exception is any comparisons between the Aboriginal and Torres Strait Islander and non-Indigenous populations. For these comparisons the Symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R99) grouping is included. This aligns with the WHO recommendation to include this grouping when comparing smaller populations that may have higher numbers of deaths due to this cause grouping. As deaths in this grouping are likely to be affected by revisions, the leading cause rankings may change once the data has been revised. 

Data by leading causes is presented in the Underlying causes of death data cubes (1-9) and the '15. Deaths of Aboriginal and Torres Strait Islander Australians' data cube in this publication.

Death rates enable more meaningful comparisons between population groups of different sizes by presenting the number of deaths against population estimates. Rates throughout this publication are calculated as the number of deaths per 100,000 people (with the exception of perinatal and infant death rates discussed below). This differs from the presentation of rates in Deaths, Australia which presents rates per 1,000 people.

In 2022, numbers have been presented by registration year rather than reference year. Death rates in 2022 are based on registration year for the numerator and reference-year-based population estimates for the denominator.

Crude and age-specific death rates

The crude death rate (CDR) is the number of deaths registered during the year per 100,000 estimated resident population at 30 June of the same year.

Age-specific death rates (ASDRs) are the number of deaths registered during the year at a specified age per 100,000 of the estimated resident population of the same age at the mid-point of the same year (30 June).

Infant mortality rates (IMRs) (those under 1 year of age) are calculated per 1,000 live births for that year.

Perinatal death rates

Perinatal death rates are the number of perinatal deaths in a registration year (i.e. fetal and neonatal deaths) per 1,000 ‘all births’ in the same reference year. All births comprises all live births plus all stillbirths (ie. fetal deaths - gestation at least 20 weeks or birth weight at least 400 grams) for a specific year.

Fetal death rates are the number of fetal deaths in a registration year per 1,000 'all births' in the same year.

Neonatal death rates are the number of deaths within 28 completed days of live born babies in a registration year per 1,000 live births in the same reference year.

Age-standardised death rates (SDRs)

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. 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 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, mortality rates for 2013-2022 have been calculated using population estimates and projections for the relevant year based on the 2021 Census.

Rates for Aboriginal and Torres Strait Islander people for 2013-2022 have been calculated using population estimates and projections for the relevant year based on the 2016 Census. Non-Indigenous estimates for the relevant years have been derived by subtracting Aboriginal and Torres Strait Islander population estimates based on the 2016 Census from the total Australian estimated resident population (ERP) based on the 2021 Census. 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.

For more details on data used in calculating death rates, refer to the Appendix - data used in calculating death rates.

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.

A death may be coded as due to suicide when:

• A coroner makes a formal finding stating the death was due to suicide.
• If a formal finding is not made (i.e. the coroner does not state the intent), an investigation of information on the NCIS may indicate a death was due to suicide. Information that would be used by a mortality coder to record a death as being due to 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.  
• For an open coronial investigation, the police may record the death as being a suspected suicide. Open cases are reviewed by the ABS when closed as part of the annual revisions process.

These coding guidelines have been applied since 1 January 2007. Previously, coding rules required a coroner to determine a death as intentional self-harm for it to be coded to suicide.

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.

From 2006 onwards, the ABS implemented a revisions process for coroner certified deaths where deaths with an open coronial investigation at the time of initial coding by the ABS have since been finalised.  The revisions process 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 (2001-2005), 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.

The 2022 published outputs include 2022 preliminary data, 2021 preliminary revised data and 2020 revised data. Data for reference years up to and including 2019 are considered final and no longer subject to the revisions process. The number of deaths attributed to intentional self-harm for 2020, 2021 and 2022 is expected to increase as data is reviewed as part of the revisions process. At the time of coding 2021 and 2022 data, there was a higher proportion of open coroner cases at preliminary coding than seen in previous years (67.2% in 2021 and 65.2% in 2022 versus a 5-year average for 2015-2019 of 56.2%). This is reflected in the 2021 and 2022 data by a higher rate of deaths due to other ill-defined and unspecified causes of mortality (R99). For further information, see the Data quality section and the Revisions Technical Notes in Causes of Death, Australia methodology, 2021.

Deaths that are referred to the coroner are more likely to take longer to be registered, especially those which are due to external causes, including suicide, homicide and drug-related deaths. These delayed registrations can sometimes create large yearly variation in some causes of deaths and for some populations, for example deaths of Aboriginal and Torres Strait Islander people.

Over recent years, for some jurisdictions, there has been an increasing delay in information flowing between the coroner court and the National Coronial Information Service (NCIS), including uploading autopsy reports, toxicology reports and coronial findings, and updating the closure status. Some jurisdictions are more affected than others. This may mean the number of deaths coded to suicide will continue to change as further information is received and data is revised. For statistics on case closure and document attachment for each jurisdiction, refer to the Operational Statistics published on the NCIS website.

More broadly, various factors including administrative and system changes, certification practices, the timeliness of information flows, classification updates or coding rule changes can impact on the mortality dataset. The sections below highlight some state-specific administrative factors that have had an impact on the number of suicide deaths over time. Data users should be cautious when making comparisons between reference periods.

As a result of two reconciliation exercises conducted jointly between the ABS and the Victorian Registry of Births Deaths and Marriages (Victorian RBDM), additional historical registrations of suicide were identified that had not been previously provided to the ABS.

• The first exercise (conducted in the first quarter of 2020) resulted in the identification of an additional 180 suicides that were registered in Victoria in 2017 (88 suicides) and 2018 (92 suicides) but not previously supplied to the ABS. 
• The second exercise (conducted in the first quarter of 2022) resulted in the identification of an additional 72 suicides that were registered in Victoria in 2013 (20 suicides), 2014 (14 suicides), 2015 (8 suicides) and 2016 (30 suicides) that were not previously supplied to the ABS.  

For the 2022 publication, data is presented by year of registration including the additional Victorian registrations obtained during both reconciliation exercises. This means the number of deaths for a particular year is more representative of the deaths that were registered in that year. For more information on these deaths and how they were presented in previous publications, refer to Technical note: Victorian additional registrations and time series adjustment in Causes of Death, Australia, 2019 and Technical note: Victorian additional registrations (2013-2016) in Causes of Death, Australia, 2021.

Additionally, as part of the implementation of the new registration system in Victoria in February 2019, there was a change in the way coroner referred deaths are reported to the ABS. Previously, only cases where the coronial case had closed were reported to the ABS, often leading to significant delays in reporting. From 2019, interim registrations (open cases) have been submitted to the ABS resulting in more timely delivery of death registration information to the ABS and an improvement in the quality of preliminary coding in relation to deaths due to suicide.

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 (DRF) and the Medical Certificate of Cause of Death (MCCD). However it is recognised that not all such deaths are captured through these processes, which may lead 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 sometimes concerns regarding the accuracy of the data.

The ABS Deaths and Causes of Death reports identify 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 DRF. The Aboriginal and Torres Strait Islander origin is also derived from the MCCD. The use of this information from the MCCD has been introduced at different times across jurisdictions depending on when systems and processes have allowed for the ABS to use as follows:  

• From 2007 for South Australia, Western Australia, Tasmania, the Northern Territory and the Australian Capital Territory.
• From 2015 for Queensland. This resulted in a noticeable decrease in the number of deaths for which the Indigenous status was ‘not stated’ and an increase in the number of deaths identified as Aboriginal and Torres Strait Islander people in Queensland in comparison to previous years. This impact is discussed in Life Tables for Aboriginal and Torres Strait Islander Australians (see Data linkage to derive Aboriginal and Torres Strait Islander deaths identification rates).
• For 2022 for New South Wales, information from the MCCD has been used for the first time. For more information on this change and the impacts refer to Technical Note: The impact of using two sources for deriving the Indigenous status of deaths in NSW in 2022.
• For Victoria, the Aboriginal and Torres Strait Islander origin of the deceased continues to be 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
• cultural aspects and feelings associated with identifying as Aboriginal and Torres Strait Islander Australian.

Additionally, 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 2022, there were 975 deaths registered in Australia for whom the Aboriginal and Torres Strait Islander origin was not stated, representing 0.5% of all deaths registered, a slight decrease from 2021 (0.6%). This difference was largely driven by fewer deaths with a not stated Aboriginal and Torres Strait Islander origin registered in New South Wales (from 463 in 2021 to 175 in 2022). 

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. Data presented may underestimate the number of deaths of Aboriginal and Torres Strait Islander people due to factors relating to form completion and propensity for an informant to identify the deceased as being of Aboriginal and Torres Strait Islander origin. Additionally, a higher proportion of deaths of Aboriginal and Torres Strait Islander people are referred to a coroner. Coroner referred deaths can take longer to register which may cause some disparities in annual registration data.

Information on causes of death relating to Aboriginal and Torres Strait Islander people is included in articles and data cubes in this publication. Limited data is presented for all states and territories, with more detailed data reported by jurisdiction of usual residence for New South Wales, Queensland, South Australia, Western Australia and the Northern Territory only. These jurisdictions have been found to have a higher quality of identification of Aboriginal and Torres Strait Islander origin allowing more robust analysis of data. Data for those with a usual residence in Victoria, Tasmania and the Australian Capital Territory has been excluded from the more detailed analysis. This is in line with national reporting guidelines. 

Individual state/territory disaggregations of deaths of Aboriginal and Torres Strait Islander Australians by WHO Leading Causes 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 age-standardised death rates (SDRs). 

Rates for Aboriginal and Torres Strait Islander people for 2013-2022 have been calculated using population estimates and projections for the relevant year based on the 2016 Census. Non-Indigenous estimates for the relevant years have been derived by subtracting Aboriginal and Torres Strait Islander population estimates based on the 2016 Census from the total Australian estimated resident population (ERP) based on 2021 Census. 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.

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.

The ABS produces estimates of life expectancy for Aboriginal and Torres Strait Islander people. For the latest estimates, refer to Life Tables for Aboriginal and Torres Strait Islander Australians. Estimates are presented for Australia, selected states and territories, remoteness areas and SEIFA (Index of Relative Socio-Economic Disadvantage). This publication also includes a summary of the outcomes of quality studies conducted as part of the Census Data Enhancement (CDE) project which investigated the levels and consistency of Aboriginal and Torres Strait Islander identification between the 2016 Census and death registrations. The outcomes of the CDE study are used to derive identification rates and feed into the life expectancy estimates.

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 (also referred to as stillbirths) 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 fewer and birth weight of 399 grams or less). This scope was adopted for the 2007 Perinatal Deaths collection and 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 deaths data cube in this release (see Table 15.21).

The scope of the ABS Perinatal collection 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.

In ABS collections:

• Fetal deaths are part of the Perinatal collection. They are not in scope of the Births,  Deaths, or Causes of Death reports. 
• Neonatal deaths are in scope of the Deaths, Causes of Death and Perinatal reports.

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.

For most jurisdictions, this publication only includes information on registered fetal and neonatal deaths. Registered deaths are sourced through jurisdictional Registries of Births, Deaths and Marriages. For Tasmania only, in addition to registered fetal deaths, data includes notifications of stillbirths that have not been registered.

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 compares ABS and NPMDC numbers of stillbirths and neonatal deaths. It 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 this data. For more information on the AIHW collection, refer to Australia’s mothers and babies: Stillbirths and neonatal deaths.

For perinatal data in the Causes of Death, Australia, 2013 publication, the ABS began a review of coding of perinatal deaths, which resulted in an interim change to outputs. Neonatal deaths were no longer assigned an underlying cause of death when output in tables of all ages (refer to Changes to Perinatal Death Coding Technical Note in Causes of Death, Australia, 2013 (cat. no. 3303.0)). Further review and consultation has resulted in a new method of coding. 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 neonatal deaths to deaths of the general population which are certified using the Medical Certificate of Cause of Death. The change reinstates the condition arising in the mother being assigned as an underlying cause of death. This method has been applied from 2014, and has also been applied retrospectively to 2013 neonatal data. Please see the Changes to Perinatal Death Coding Technical Note in Causes of Death, Australia, 2014 (cat. no. 3303.0) for further details.

From 2013, changes have led to a reduction in the number of both stillbirths and neonatal deaths where a 'main condition in mother' was recorded. This has led to a reduction in deaths 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 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.

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. Also refer to ‘Live birth counts used in mortality rate denominators’ section of Data quality for information about the quality of live birth counts.

There are a very small number of stillbirth (fetal deaths) registrations provided to the ABS each year where the sex at birth 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 
• a clinical determination of sex may not be able to be clearly determined. This may be due to a number of reasons including extreme prematurity or some congenital conditions.

Where the sex at birth 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 10 stillbirths registered in 2022 where the sex at birth was not specified.

South Australian fetal deaths

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 15.19 and 15.20 of the Perinatal data cube in this publication was revised in the 2019 report.

1. In 2022, there were 1,691 deaths of Aboriginal and Torres Strait Islander people whose usual residence was New South Wales (NSW). This represents an increase in recorded deaths of 40.2% (485 deaths) from 2021. Just over two-thirds of this increase (67.6% or 328 deaths) is explained by an improvement in the methodology used for deriving the Indigenous status of people whose death was registered in NSW. Specifically, the Medical Certificate of Cause of Death (MCCD) was made available to the ABS by the NSW Registry of Births, Deaths and Marriages as a secondary source for determining the Indigenous status of the deceased. Use of this additional source has led to improved recording of Indigenous status. Alongside increases in the number of deaths of Aboriginal and Torres Strait Islander people and non-Indigenous people, there was a corresponding reduction in the number of deaths for which the Indigenous status of the deceased was not stated.

2. This change has introduced a break in time series in Aboriginal and Torres Strait Islander death statistics in New South Wales and consequentially in Australia.

3. ABS deaths data is sourced from death registrations provided by each state and territory Registry of Births, Deaths and Marriages. Information contained in the death registration is from two main sources:

• The Death Registration Statement (DRS) - also referred to as the Death Registration Form (DRF). This is completed by the informant (usually the funeral director and the family) and comprises of a range of demographic information relating to the deceased. The ABS uses information from the DRS to compile demographic information about deaths in Australia including age, usual residence and Indigenous status.
• The cause of death process. Each death is certified by either a doctor or a coroner. For doctor-certified deaths, information is sourced from the Medical Certificate of Cause of Death (MCCD), or the Medical Certificate of Cause of Perinatal Death (MCCPD) for fetal and neonatal deaths. For coroner-referred deaths, the information provided on these forms is ascertained from the coronial investigation process, which may include information from an autopsy, police investigation or other reports (such as toxicology). The ABS uses the cause of death information from these forms to conduct mortality coding and assign an underlying cause of death. For most jurisdictions, the ABS also uses the Indigenous status that is reported on the MCCD as a second source.

4. Before 2022, the Indigenous status of deaths registered in NSW was derived from the DRS only. From 2022, information on Indigenous status from the MCCD was made available to the ABS, and was subsequently used to ascertain whether a deceased person was of Aboriginal or Torres Strait Islander origin. This change now aligns NSW deaths data for Aboriginal and Torres Strait Islander people with most other jurisdictions, where both the DRS and the MCCD have been used for a number of years. Victoria is the only jurisdiction where the MCCD is not used.

5. In ABS outputs the deceased is reported as being of Aboriginal and Torres Strait Islander origin when recorded as such on either the DRS or MCCD. If the two sources do not agree, identification on either source is given preference over recording the deceased as non-Indigenous. To ensure the addition of the MCCD in NSW resulted in an improvement to data for deaths of Aboriginal and Torres Strait Islander people, the ABS worked with stakeholders, including the NSW Registry and the Coroners Court of NSW, to assess deaths where the Indigenous status differed between the MCCD and the DRS. This quality assurance process led to corrections for some records.

Usual residence

6. Throughout the Deaths and Causes of Death publications, data is presented by usual residence of the deceased. Each year, a small proportion of deaths are registered outside the state or territory of usual residence of the deceased. In 2022:

• 41 (2.4%) deaths of Aboriginal and Torres Strait Islander people with a usual residence of NSW were registered outside NSW, and therefore were unaffected by this change
• 14 (0.8%) Aboriginal and Torres Strait Islander deaths registered in NSW were usual residents of other states and territories. As these 14 deaths were registered in NSW, the new methodology for deriving Indigenous status was applied, however, they will be presented in the jurisdiction in which the deceased usually resided. This change has minimal impact on usual residence outputs for other jurisdictions. 

Indigenous status

7. Table 1 highlights the impact of using both the DRS and MCCD to derive Indigenous status compared to using the DRS alone. For NSW data in 2022:

• using both sources, there were 1,691 Aboriginal and Torres Strait Islander deaths, an increase of 485 deaths (40.2%) compared to 2021
• if only the DRS was used for ascertaining the Aboriginal and Torres Strait Islander origin of the deceased (the historical method) there would be 1,363 Aboriginal and Torres Strait Islander deaths, an increase of 157 deaths (13.0%) compared to 2021
• use of the MCCD resulted in an additional 328 deaths where the person was identified as being of Aboriginal and Torres Strait Islander origin
• using the MCCD as an additional source has led to a substantial improvement in the data, with 275 (61.0%) fewer deaths having an Indigenous status of 'not stated' compared to 2021.

8. Table 2 highlights the impact of using both the DRS and MCCD for deriving Indigenous status, by certifier type (doctor or coroner). In NSW in 2022:  

• using both sources resulted in a greater proportion of doctor- and coroner-referred deaths of Aboriginal and Torres Strait Islander origin, compared to 2021. Using both sources, 2.2% of doctor-certified deaths and 7.4% of coroner-referred deaths were of Aboriginal and Torres Strait Islander origin
• overall, the proportion of Aboriginal and Torres Strait Islander deaths to all deaths increased from 2.1% in 2021 to 2.7% in 2022
• using both sources resulted in an increase in the proportion of doctor-certified non-Indigenous deaths, but a decreased proportion of coroner-referred non-Indigenous deaths compared to 2021
• overall, the proportion of non-Indigenous deaths in NSW was stable between 2021 (97.1%) and 2022 (97.0%), regardless of source type.

Infant deaths

9. Table 3 highlights the impact of using both the DRS and MCCD for deriving Indigenous status for infant deaths. The number and rate of neonatal deaths (deaths of live-born babies within the first 28 days) are presented separately. Infant Mortality Rates (IMR) in the Deaths, Australia publication are presented based on a three-year average (ending in the reference year). IMRs presented in this technical note are by single year to demonstrate the impact of the change in method on 2022 data specifically.  

10. Use of the MCCD in NSW in 2022:

• resulted in an increase in both the count and IMR of Aboriginal and Torres Strait Islander infants compared to 2021. The total infant mortality rate for Aboriginal and Torres Strait Islander infants increased from 3.7 deaths per 1,000 live births in 2021, to 4.0 in 2022
• resulted in a slight decrease in the number of deaths of non-Indigenous infants
• did not affect the non-Indigenous infant mortality rate in 2022, which was 2.5 deaths per 1,000 live births irrespective of the method used to ascertain Indigenous status.  

Median age and standardised death rates

11. Tables 4 to 6 summarise the impact of this change on Aboriginal and Torres Strait Islander deaths for key data items, including median age, age-standardised death rates (SDRs) and leading causes of death. SDRs in the Deaths, Australia publication are presented based on a three-year average (ending in the reference year). SDRs presented in this technical note are by single year to demonstrate the impact of the change in method on 2022 data specifically. 

12. In NSW in 2022:

• the median age of death for Aboriginal and Torres Strait Islander people increased for males, females and persons compared to 2021, regardless of method applied to derive Indigenous status
• the median age of death for Aboriginal and Torres Strait Islander people is 64.8 years. If the historical method had been in place, the median age at death would have been 65.5 years. A lower median age at death is recorded for both males and females with the addition of the MCCD. This lower median age at death is likely due to the higher proportion of external causes of death, including suicides and land transport accidents, in people identified as being Aboriginal and Torres Strait Islander through the MCCD. External causes of death typically occur in younger age cohorts.

13. In NSW in 2022, the age-standardised death rate (SDR):

• increased for deaths of Aboriginal and Torres Strait Islander males, females and persons compared to 2021, regardless of method applied to derive Indigenous status
• was 10.8 deaths per 1,000 persons for Aboriginal and Torres Strait Islander people. If the historical method had been used, the SDR would have been 8.8 deaths per 1,000 persons. 

Leading causes of death

14. Table 6 presents data by leading cause of death and source type for 2021 and 2022.

• Ischaemic heart diseases (I20-I25) remained the leading cause of death for Aboriginal and Torres Strait Islander males and persons in 2022. Chronic lower respiratory diseases (J40-J47) remained the leading cause of death for Aboriginal and Torres Strait Islander females. The leading cause of death for Aboriginal and Torres Strait Islander people would have remained the same irrespective of which method was used to determine Indigenous status. While the rank did not change for ischaemic heart diseases (for males and persons) and chronic lower respiratory diseases (for females), the number of deaths due to these diseases did increase with the addition of the MCCD.
• When using both sources, the top five leading causes of Aboriginal and Torres Strait Islander deaths were the same in 2021 and 2022 for males, females and persons. The only change was in the leading cause ranking for females, for whom ischaemic heart diseases (I20-I25) became the second leading cause of death over lung cancer (C33-C34), which moved to third place. While ranking of leading causes of death was minimally affected with the use of the MCCD, the number of deaths increased across all top ten leading cause categories.

1. Deaths that are referred to a coroner can take time to be fully investigated. To account for this, the ABS implemented a revisions process for those deaths where coronial investigations remained open at the time preliminary cause of death codes were assigned. Typically, the revisions process is commenced 12 and 24 months after data is first published. Data is deemed preliminary when first published, revised when published the following year and final when published after a second year.

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 considered 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 key improvements to Causes of Death data gained through the revisions process:

• For deaths from natural causes a more specified condition may be identified. For example, a death may have a preliminary code of unspecified heart disease (I51.9), but with the later addition of an autopsy report, coronary artery disease (I25.1) is identified with the updated code applied through the revisions process.
• 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 updated to report the injury as being caused by a fall down steps.
• External causes may also have the intent of death updated through revisions. For example, a drug-induced death where the intent of death was not determined at preliminary coding, may be updated to an intentional drug-induced death (i.e., suicide) when a coronial finding has been made.
• Injury and poisoning information may be updated. For example, at preliminary coding a drug-induced death may not yet have the specific drugs contributing to death documented. While the death will be counted as drug-induced in nature, the drug code will remain unspecified (T509, unspecified drugs, medicaments and biological substances). The death may later be found to be a mixed drug toxicity with heroin, benzodiazepine and alcohol involvement.
• Deaths caused by Accidental drug poisoning (X40-X44), Intentional self-harm by mechanism of drug poisoning (X60-X64) and Sudden Infant Death Syndrome (SIDS) (R95) are particularly sensitive to the revisions process. 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. As investigations progress and reports are uploaded to the NCIS, more detailed information regarding the context of the death can be captured.
• Associated cause and risk factor information may also be added as part of the revisions process. For example, a death may be coded as due to suicide. At the completion of a coronial investigation further information may be made available regarding personal circumstances of the deceased including presence of chronic disease, mental health conditions and drug and alcohol use. Since 2017, psychosocial risk factors (e.g. financial issues, relationship issues) relating to the deceased have been coded alongside other co-morbidities. These factors may also be added to a death record as part of the revisions process.

4. Included in the scope of revisions for a given reference period are:

• Deaths referred to the coroner where the investigation remains open,
• Coroner certified deaths where the investigation has closed since the last revisions cycle,
• Coroner certified deaths where additional information has been added to the NCIS since last coded, and
• Doctor certified deaths where updated or corrected cause of death information has been supplied to and processed by the ABS.

For further information regarding the scope of cause of death statistics, see Data collection.

5. Various improvements to the availability and timeliness of national mortality information have been undertaken over several years. One major improvement is the more timely upload of reports and information for open coroner cases to the NCIS. This information can then be used at an earlier point by the ABS to improve the quality of open coding for deaths referred to the coroner. 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.

6. Until the 2014 processing cycle, 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). Causes of Death, Australia, 2015 was released 6 months earlier, representing a significant change in processing of the national mortality dataset. 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.

7. 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. As 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.

8. The earlier release of data resulted in a higher number of deaths coded to Symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R99) at preliminary coding. Subsequently, since the change to the revisions process in 2015, there has been a larger proportional decrease in deaths coded to R00-R99 after the first round of revisions coding has occurred. The graph below shows the proportional decrease in deaths coded to R00-R99 by year after the revisions process has been applied.

9. At the time of coding, 2022 data had a higher proportion of open coroner cases than at the time of preliminary coding in previous years.  This is evident in the preliminary 2022 dataset by a higher proportion of deaths due to Other ill-defined and unspecified causes of mortality (R99). To address this, an early targeted revision of 2022 deaths referred to a coroner has been conducted with the aim of assigning more specified causes to underlying and associated causes that are ill-defined in nature.

10. Deaths in scope for the 2022 preliminary revision include those with an underlying cause of Other ill-defined and unspecified causes of mortality (R99), Exposure to unspecified factor causing other and unspecified injury (X59.9) and Event of undetermined intent (Y10-Y34), as well as deaths with an underlying cause of drug poisoning (X40-X44, X60-X64, X85, Y10-Y14) with an associated cause of Poisoning by other and unspecified drugs, medicaments and biological substances (T50.9). Data for 2022 is considered to be preliminarily revised. For further information on the scope and outcomes of this early revision to 2022 data, see Technical note: Causes of death revisions, 2022 preliminary revision.

1. This technical note focuses specifically on the cause of death revisions process applied to deaths registered in 2020. This is the second revision to this dataset meaning 2020 registration year data is now considered final. For further information on the methods and scope of the revisions process, see Technical note: Causes of death revisions methodology in this publication.

Doctor certified deaths

2. An issue was identified with cause of death data for deaths with specified viruses such as respiratory syncytial virus (RSV) or parainfluenza virus certified as an underlying or associated cause of death. In some instances, the assignment of ICD-10 codes by the ABS’ auto-coding software meant that these causes of death were indistinguishable in the dataset. Impacted records had an underlying or associated cause of Viral infection of unspecified site (B34), Viral agents as the cause of diseases classified to other chapters (B97) or Viral pneumonia, not elsewhere classified (J12). This update enables greater specificity in the codes assigned, allowing more accurate surveillance of mortality patterns related to viral diseases in Australia. The coding changes applied to 2020 data are summarised in Table 1 below.

Coroner certified deaths

3. Most changes during a revisions process occur to deaths that were referred to a coroner. This is due to updates and changes to information and reports available to the ABS as the coronial investigation progresses. The remainder of this technical note will focus on changes to coroner referred deaths.

4. Table 2 provides the counts of coroner certified deaths by ICD-10 chapter for the 2020 reference period across the revisions process. Revisions are most likely to result in decreases in the number of deaths coded to Symptoms and signs (R00-R99) with corresponding increases in other chapters.

5. Deaths which are originally coded to the Symptoms and signs (R00-R99) chapter can be reassigned to specific natural or external causes of death. In 2020, over two thirds of those reassigned from R00-R99 were found to be deaths from natural causes, with Diseases of the circulatory system (I00-I99) being the most common natural cause chapter for deaths to be reassigned to.

6. Of those reassigned from Symptoms and signs (R00-R99) chapter to external causes of death: 

• 100 were found to be accidental drug-induced deaths (X40-X44),
• 80 were deaths due to other accidents with a specified mechanism (V00-X39, X45-X58 , Y85), and
• 23 were deaths due to intentional self-harm (suicide) (X60-X84, Y87.0).

7. There were 125 deaths that were updated from being coroner certified to doctor certified across the 2020 revisions cycle. When a death occurs, it may be referred to a coroner for investigation. During this time the death record may be sent to the ABS and be flagged as a coronial death. At a later point in the process the death may be deemed as non-reportable, and a doctor completes a medical certificate of cause of death. The ABS may not be informed immediately of the change, meaning the certifier type may be updated at a later time and incorporated as part of the revisions process. As a result, the total number of coroner certified deaths may differ from preliminary to revised and revised to final data.

8. The purpose of the revisions process is to improve data quality. Enhancements to the quality of underlying cause data may include improvements to either mechanism or intent or identifying an underlying cause where not previously possible. While the revisions process has some impact on statistical output at the chapter level of the ICD-10 (particularly for R00-R99), data improvements become more apparent when considering movements within individual chapters.

9. Table 3 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 2020 revisions period. There were 171 deaths where intent was specified at preliminary coding, but the mechanism of death was unknown. This decreased by 113 deaths (66.1%) through the revisions process. The majority of these deaths did not change intent. For example, a death due to suicide where the mechanism was unspecified at preliminary coding (Intentional self-harm by unspecified means (X84)) may be revised to a suicide with mechanism of drowning (Intentional self-harm by drowning (X71)) as an autopsy becomes available for analysis.

10. Cases coded to Ill-defined and unspecified causes of mortality (R99) decreased by 40.3% over the full 2020 revisions process (preliminary to final).

11. Table 4 provides information on changes at the sub-chapter level for the 2020 reference period, with a focus on External causes of morbidity and mortality (V01-Y98). Deaths due to external causes often require more extensive investigations to accurately determine the cause, manner, and intent of the death, and can be subject to greater change across revisions cycles. As investigations are finalised, more information generally becomes available on the NCIS and coders may use this information to further specify or update causes of death.

12. Notable increases in deaths due to external causes over the full revisions process include:

• Accidental drug-induced deaths (X40-X44) increased by 136 deaths. The majority of these were originally coded to Other ill-defined and unspecified causes of mortality (R99).
• Accidental falls increased by 76 deaths.
• Intentional self-harm (X60-X84, Y87.0) increased by 46 deaths. Over half of these deaths retained the mechanism of death assigned during preliminary coding, with intent information becoming available as coronial investigations were finalised.
• Car occupant injured in transport accident (V40-V49) increased by 12 deaths. Most of these deaths were originally coded to Crashing of motor vehicle, undetermined intent (Y32) or Motor- or nonmotor-vehicle accident, type of vehicle unspecified (V89).

Drug-induced deaths

13. 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. 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.

14. Over the revisions process there was a net increase of 124 coroner certified drug-induced deaths (includes all intents: Accidental (X40-X44), Intentional (X60-X64), Assault (X85) and Undetermined (Y10-Y14)).

15. Accidental drug-induced deaths (X40-X44) are sensitive to the revisions process. From preliminary to final, there were 183 deaths reassigned to Accidental drug-induced deaths and 45 deaths reassigned from Accidental drug-induced deaths to another category.

16. For newly assigned accidental drug-induced deaths:

• 100 deaths were initially coded to Other ill-defined and unspecified causes of mortality (R99). These deaths typically had only a police report available at preliminary coding, where circumstances surrounding death can be unclear and often present similarly to deaths from natural causes.
• 46 deaths were initially coded to a drug-induced death of undetermined intent (Y10-Y14).

17. For deaths that were initially coded to accidental drug-induced deaths but have since been reassigned: 

• 31 deaths were reassigned to a drug-induced death of a different intent type.
• The remainder were reassigned to other external causes and some natural causes.

18. From preliminary to final, there were 54 deaths reassigned to Intentional (i.e. suicide) drug-induced deaths (X60-X64) and 34 deaths reassigned from this group.

• 63.0% of newly assigned Intentional drug-induced deaths were already coded to a drug-induced death of a different intent.
• The remainder were initially coded to Other ill-defined and unspecified causes of mortality (R99) (20.4%) or suicide with a mechanism other than drug poisoning (16.7%).

19. Coronial investigations can result in changes to the both intent and drug type for deaths already established as drug-induced during preliminary coding. Over half (51.6%) of the deaths that were revised within the drug-induced death category across the 2020 revisions period were already established as drug-induced during preliminary coding. These deaths had an update to the either the intent or drug type contributing to death.

• 68.2% deaths had a change to intent type with no change to the drug type (e.g. X41 to X61).
• 24.2% deaths had a change to the drug type identified with no change to intent type (e.g. X41 to X44).
• The remaining 7.6% had a change to both intent type and drug type identified (e.g. Y61 to Y14).

20. 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, with fewer changes to underlying causes between revision iterations. As a result, a significant proportion of the 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, mental and behavioural disorders, and psychosocial risk factors implicated in deaths from external causes.

Associated causes for drug-induced deaths

21. Policies directed at reducing drug-induced deaths employ a variety of strategies which can depend on drug type. Information regarding the type of drug(s) in a drug-induced death can be reliant on the availability of an autopsy, toxicology or coronial finding report. When these reports are not available, the drug type may be unknown to the ABS and coded to Other and unspecified drugs, medicaments and biological substances (Unspecified drug) (T50.9). Importantly, deaths coded with an Unspecified drug (T50.9) 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. From preliminary to final, the number of drug-induced deaths in 2020 where drug type was not specified (T50.9) decreased from 89 to 9.

22. Individual drug types (four-digit ICD-10 code) increased over the revisions period. This results from both the decrease in deaths assigned an unspecified drug (see paragraph 21) and the addition of deaths identified as drug-induced (see paragraphs 13-14). Benzodiazepines (T42.4) recorded the largest increase (127 additional mentions), followed by Psychostimulants with abuse potential (T43.6) (75 additional mentions) and Other and unspecified antidepressants (T43.2) (65 additional mentions).

23. Associated causes of death may also provide critical insights into risk factors for drug-induced deaths, and these factors may differ by intent of death. Table 7 shows the most common associated causes of death and psychosocial risk factors (excluding drug types) added to accidental drug-induced deaths over the revisions process. Of note:

• Chronic substance use disorders were identified in an additional 206 accidental drug-induced deaths over the revisions process.
• Mood disorders (F30-F39), including depression and bipolar affective disorder, were identified in an additional 141 deaths.
• Problems related to legal circumstance (Z65.0-Z65.4) was the most commonly mentioned psychosocial risk factor associated with accidental drug-induced deaths, and was identified in an additional 76 deaths.

Associated causes for intentional self-harm (suicide)

24. Associated causes of death can provide important contextual information for deaths due to Intentional self-harm (X60-X84, Y87.0). At preliminary coding, 88.5% of suicides had associated causes (including chronic conditions and psychosocial risk factors) mentioned in coronial investigation documentation on the NCIS. Through the revisions process, this proportion increased to 95.4%. Table 8 shows the most common associated causes of death added over the revisions process as they relate to Intentional self-harm (X60-X84, Y87.0).

25. Notable changes in associated causes for deaths due to intentional self-harm across the 2020 revisions process include the following:

• Suicide ideation (R45.8) had the greatest increase in frequency through revisions, identified in an additional 303 deaths.
• Mood disorders (F30-F39), including depression and bipolar affective disorder, were the most common associated cause overall for deaths due to suicide, identified in an additional 289 deaths.
• Personal history of self-harm (Z91.5) was the most common psychosocial risk factor in deaths due to suicide, and was identified in an additional 190 deaths over the revisions period.
• Identification of chronic alcohol and psychoactive substance use disorders increased by over 30% during revisions, whilst identification of acute alcohol and psychoactive substance use and intoxication increased by over 20%.

1. This technical note focuses on the revisions process applied to deaths registered in 2021. This is the first full revision of this dataset meaning 2021 registration year is now considered revised. A preliminary revision on the 2021 dataset was conducted previously on selected underlying causes of death that are ill-defined in nature. The three causes of death targeted in the preliminary revision were Other ill-defined and unspecified causes of mortality (R99), Exposure to unspecified factor (X59) and Unspecified event, undetermined intent (Y34). For further information on the methods and scope of the revisions process, see Technical note: Causes of death revisions methodology.

Doctor certified deaths

2. An issue was identified with cause of death data for deaths with specified viruses such as respiratory syncytial virus (RSV) or parainfluenza virus certified as an underlying or associated cause of death. In some instances, the assignment of ICD-10 codes by the ABS’ auto-coding software meant that these causes of death were indistinguishable in the dataset. Impacted records had an underlying or associated cause of Viral infection of unspecified site (B34), Viral agents as the cause of diseases classified to other chapters (B97) or Viral pneumonia, not elsewhere classified (J12). This update enables greater specificity in the codes assigned, allowing more accurate surveillance of mortality patterns related to viral diseases in Australia. The coding changes applied to 2021 data are summarised in Table 1 below.

Coroner certified deaths

3. Most changes during a revisions process occur to deaths that were referred to a coroner. This is due to updates and changes to information and reports available to the ABS as the coronial investigation progresses. The remainder of this technical note will focus on changes to coroner referred deaths.

4. Table 2 provides the counts of coroner certified deaths by ICD-10 chapter for the 2021 reference period from preliminary to revised. Revisions are most likely to result in decreases in the number of deaths coded to Symptoms and signs (R00-R99) with corresponding increases in other chapters.

5. Deaths which are originally coded to the Symptoms and signs (R00-R99) chapter can be reassigned to specific natural or external causes of death. In 2021, the majority (62.9%)  of those reassigned from R00-R99 were subsequently found to be deaths from natural causes, with Diseases of the circulatory system (I00-I99) being the most common natural cause chapter for deaths to be reassigned to.

6. Of those reassigned to external causes of death:

• 99 were found to be accidental drug-induced deaths (X40-X44),
• 78 were deaths due to other accidents with a specified mechanism (V00-X39, X45-X58), and
• 25 were deaths due to Intentional self-harm (suicide) (X60-X84, Y87.0).

7. There were 23 death records that were updated from being coroner certified to doctor certified across the 2020 revisions cycle. When a death occurs, it may be referred to a coroner for investigation. During this time the death record may be sent to the ABS and be flagged as a coronial death. At a later point in the process the death may be deemed as non-reportable, and a doctor completes a medical certificate of cause of death. The ABS may not be informed immediately of the change, meaning the certifier type may be updated at a later time and incorporated as part of the revisions process. As a result, the total number of coroner certified deaths may differ from preliminary to revised data.

8. The purpose of the revisions process is to improve data quality. Enhancements to the quality of underlying cause data may include improvements to either mechanism or intent or identifying an underlying cause where not previously possible. While the revisions process has some impact on statistical output at the chapter level of the ICD-10 (particularly for R00-R99), data improvements become more apparent when considering movements within individual chapters.

9. Table 3 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 2021 revisions period. There were 215 deaths where intent was specified at preliminary coding but the mechanism of death was unknown. This decreased by 96 deaths (44.7%) through the revisions process. The majority of these 96 deaths did not change intent. For example, a death due to suicide where the mechanism was unspecified at preliminary coding (Intentional self-harm by unspecified means (X84)) may be revised to a suicide with mechanism of drowning (Intentional self-harm by drowning (X71)) as an autopsy becomes available for analysis.

10. For deaths certified by a coroner, cases coded to Ill-defined and unspecified causes of mortality (R99) decreased by 595 during the revision cycle. Of these, 419 were reassigned during the preliminary revision and 176 were reassigned during the current revision. This was a decrease of 28.9% over the first full revision period (preliminary to revised) which is in line with previous years.

11. Table 4 provides information on changes at the sub-chapter level for the 2021 reference period, with a focus on External causes of morbidity and mortality (V01-Y98). Deaths due to external causes often require more extensive investigations to accurately determine the cause, manner, and intent of the death, and can be subject to greater change across revisions cycles. As investigations are finalised, more information generally becomes available on the NCIS and coders may use this information to further specify or update causes of death.

12. Over the first full revision of 2021 data, the number of deaths due to external causes increased by 207 deaths. Key changes include:

• Accidental drug-induced deaths (X40-X44) increased by 127 deaths.
• Accidental falls (W00-W19) increased by 83 deaths.
• Intentional self-harm (X60-X84, Y870) increased by 53 deaths. The majority of these 53 deaths were originally coded to an event of undetermined intent (Y10-Y34).
• Deaths with an undetermined intent (Y10-Y34) decreased by 57. Generally, a more specific intent was able to be assigned with the availability of more information in coronial reports.

Drug-induced deaths

13. 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. 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.

14. From preliminary to revised there was a net increase of 124 coroner certified drug-induced deaths (includes all intents: Accidental (X40-X44), Intentional (X60-X64), Assault (X85) and Undetermined (Y10-Y14)).

15. Accidental drug-induced deaths (X40-X44) are sensitive to the revisions process. From preliminary to final, there were 172 deaths reassigned to Accidental drug-induced deaths and 45 deaths reassigned from Accidental drug-induced deaths to another category (resulting in a net increase of 127 to this category).

16. For newly assigned drug-induced deaths:

• 99 deaths were initially coded to Other ill-defined and unspecified causes of mortality (R99). These deaths typically had only a police report available at preliminary coding, where circumstances surrounding death can be unclear and often present similarly to deaths from natural causes.
• 26 deaths were initially coded to a drug-induced death of undetermined intent (Y10-Y14).

17. For deaths that were initially coded to accidental drug-induced deaths but have since been reassigned: 

• 36 deaths were reassigned to a drug-induced death of a different intent type.
• The remainder were reassigned to other external causes and some natural causes.

18. There were 46 deaths that were reassigned to Intentional (i.e. suicide) drug-induced deaths (X60-X64). Of these:

• 60.9% were already assigned to a drug-induced death of a different intent.
• A further 30.4% were initially assigned to Other ill-defined and unspecified causes of mortality (R99).

19. Coronial investigations can result in changes to the both intent and drug type for deaths already established as drug-induced during preliminary coding. Just under half (48.8%) of the deaths that were reassigned to a drug-induced death were already assigned to a drug-induced death of a different drug or intent type during 2021 preliminary coding. 

• 71.0% deaths had a change to intent type with no change to the drug type (e.g. X41 to X61).
• 23.9% deaths had a change to the drug type identified with no change to intent type (e.g. X41 to X44).
• The remaining 5.1% had a change to both intent type and drug type identified (e.g. Y61 to Y14).

20. 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, with fewer changes to underlying causes between revision iterations. As a result, a significant proportion of the 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, mental and behavioural disorders, and psychosocial risk factors implicated in deaths from external causes.

Associated causes for drug-induced deaths

21. Policies directed at reducing drug-induced deaths employ a variety of strategies which can depend on drug type. Information regarding the type of drug(s) in a drug-induced death can be reliant on the availability of an autopsy, toxicology or coronial finding report. When these reports are not available, the drug type may be unknown to the ABS and coded to Other and unspecified drugs, medicaments and biological substances (Unspecified drug) (T50.9). Importantly, deaths coded with an Unspecified drug (T50.9) 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. From preliminary to revised, the number of drug-induced deaths in 2021 where drug type was not specified (T50.9) decreased from 77 to 18.

22. Individual drug types (four-digit ICD-10 code) increased over the revisions period. This results from both the decrease in deaths assigned an unspecified drug (see paragraph 21) and the addition of deaths identified as drug-induced (see paragraphs 13-14). Table 6 shows that Benzodiazepines (T42.4) recorded the largest increase (126 additional mentions), followed by Other opioids (T40.2) (64 additional mentions) and Psychostimulants with abuse potential (T43.6) (62 additional mentions).

23. Associated causes of death may also provide critical insights into risk factors for drug-induced deaths, and these factors may differ by intent of death. Table 7 shows the most common associated causes of death and psychosocial risk factors (excluding drug types), added to accidental drug-induced deaths over the first revision of 2021 data. Of note:

• Chronic substance use disorders were identified in an additional 207 accidental drug-induced deaths.
• Mood disorders (F30-F39), including depression and bipolar affective disorder, were identified in an additional 142 deaths, whilst anxiety and stress-related disorders (Z73.3, F40-F48 excl. F41.8, F45.4) were identified in an additional 134.
• Problems related to legal circumstance (Z65.0-Z65.4) was the most commonly mentioned psychosocial risk factor associated with accidental drug-induced deaths, and increased by 62 mentions from preliminary to revised.

Associated causes for intentional self-harm (suicide)

24. Associated causes of death and psychosocial risk factors can provide important contextual information for deaths due to Intentional self-harm (X60-X84, Y870). At preliminary coding, 86.8% of suicides in 2021 had associated causes (including chronic conditions and psychosocial risk factors) mentioned in coronial investigation documentation on the NCIS. Over the first revision, this proportion increased to 93.6% . Table 8 shows the most common associated causes of death added over the revisions process as they relate to Intentional self-harm (X60-X84, Y87.0).

25. Notable updates for associated causes and risk factors added for deaths due to intentional self-harm over the first full revision period in 2021 were:

• Mood disorders (F30-F39), including depression and bipolar affective disorder, had the largest increase from preliminary to revised and were the most common associated cause overall for deaths due to suicide.
• Suicide ideation (R45.8) and personal history of self-harm (Z91.5) were identified in an additional 267 and 186 deaths respectively.
• An additional 247 deaths identified anxiety and stress-related disorders (Z73.3, F40-F48 excl. F41.8, F45.4).
• Problems in relationships (Z63.0, Z63.5), which refers to spousal relationship issues including conflict and separation, were identified in an additional 173 deaths.

1. This technical note focuses specifically on the cause of death revisions process applied to deaths registered in 2022. Data for 2022 is considered a preliminary revision. The full revisions process for 2022 data will be applied from early 2025 with further updates likely. For further information on the methods and scope of the revisions process, see Technical note: Causes of death revisions methodology in this publication.

Doctor certified deaths

2. An issue was identified with cause of death data for deaths with specified viruses such as respiratory syncytial virus (RSV) or parainfluenza virus certified as an underlying or associated cause of death. In some instances, the assignment of ICD-10 codes by the ABS’ auto-coding software meant that these causes of death were indistinguishable in the dataset. Impacted records had an underlying or associated cause of Viral infection of unspecified site (B34), Viral agents as the cause of diseases classified to other chapters (B97) or Viral pneumonia, not elsewhere classified (J12). This update enables greater specificity in the codes assigned, allowing more accurate surveillance of mortality patterns related to viral diseases in Australia. The coding changes applied to 2022 data are summarised in Table 1 below.

Coroner certified deaths

3. Typically, coroner referred death data is revised 12 months and 24 months after data is first published. The ABS revisions process was implemented to update cause of death data for deaths that had open coronial investigations or limited information available at preliminary coding. Data is considered preliminary when first published, revised when published the following year and final when published after a second year.

4. At the time of coding 2022 data, there was a high proportion of open coroner cases (65.2%), similar to the proportion at the time of coding 2021 preliminary data (67.2%). This is higher than previous years (5-year average for 2015-2019 of 56.2%) and is reflected in the 2022 preliminary dataset by a higher proportion of deaths due to Other ill-defined and unspecified causes of mortality (R99). Cases coded to R99 made up 10.7% of the preliminary coroner certified deaths dataset in 2022. The proportion in 2021 was 9.8%. This compares with a historical average of 6.3% for preliminary data.

5. Following a usual revisions cycle, coronial cases for 2022 would have been first reviewed in early 2025. However, in consideration of the high proportion of ill-defined causes of death in the 2022 preliminary dataset, an early targeted revision of 2022 coroner certified deaths was conducted. The aim was to assign more specified causes of death and reduce the number of deaths coded to ill-defined causes. The targeted causes of death were:

• Other ill-defined and unspecified causes of mortality (R99) (all information is unknown about the cause of death),
• Exposure to unspecified factor causing other and unspecified injury (X59.9) (death was caused by an external factor but the mechanism is unknown),
• Event of undetermined intent (Y10-Y34) (the intent of death is unknown), and
• Drug-induced deaths (X40-X44, X60-X64, X85, Y10-Y14) with an associated drug type of Other and unspecified drugs, medicaments and biological substances (T50.9) (the drug type is unknown).

6. 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.

7. Table 2 below shows updated data for coroner certified deaths only for the targeted underlying causes of death (R99, X59.9 and Y10-Y34). Of deaths in scope for the 2022 revisions period, 690 were able to be reassigned to a more specific underlying causes of death.

• There was a net decrease of 660 deaths coded to ill-defined and unspecified causes of mortality (R99), reducing the total proportion of coroner certified deaths coded to R99 from 10.7% to 7.9%. This more closely aligns the 2022 dataset with historical averages for preliminary data.
• When 2022 was first released, there were 59 deaths coded to accidental intent where the mechanism was unspecified (X59.9). Through the preliminary revision, there was a net increase of 2 deaths coded to X59.9 (now 61 deaths). The change in this category comprises of: 
  • 23 deaths reassigned from X59.9 to more specific causes, and, 
  • 25 deaths reassigned from R99 to X59.9.
• There were 184 deaths coded to an event of undetermined intent (Y10-Y34). The preliminary revision resulted in a net decrease of 32 deaths assigned to this group (17.4%).

8. Table 3 shows the coding changes for deaths that were initially coded to Other ill-defined and unspecified causes of mortality (R99) for the 2022 reference period.

9. There were 661 deaths initially coded to R99 that were reassigned to more specific causes of death in the preliminary revision. Over half (59.6%) of the deaths reassigned from R99 were due to natural causes. Of these:

• There were 201 deaths reassigned to Diseases of the circulatory system (I00-I99). Ischaemic heart diseases (I20-I25) comprised the majority of these (67.7%).
• There were 41 deaths reassigned to Endocrine, nutritional and metabolic diseases (E00-E90), over half of which were deaths due to Diabetes mellitus (E10-E14).

10. The remaining 249 deaths were reassigned to external causes. Of these deaths:

• The majority were reassigned to Accidents, over half of which were reassigned to Accidental poisoning by drugs or alcohol (X40-X45).
• There were 21 deaths reassigned to Intentional self-harm (X60-X84, Y87.0).

11. Table 4 shows the coding changes for deaths that were initially coded to Exposure to unspecified factor causing other and unspecified injury (X59.9).

12. The majority (87.0%) of these deaths remained as external causes (V01-Y98). Of these:

• 14 deaths remained as accidents with updates to the mechanism of death (V01-X58).
• 4 deaths were reassigned to Intentional self-harm (X60-X84, Y87.0).

13. Table 5 shows the coding changes for deaths that were initially coded to Exposure to unspecified factor causing other and unspecified injury (X59.9).

14. The majority (90.9%) of these deaths remained classified as deaths due to external causes (V01-Y98). Of these:

• 31 deaths reassigned to Accidents (V01-X59), over half of which retained the mechanism of death identified during preliminary coding.
• 13 deaths were reassigned to Intentional self-harm (suicide) (X60-X84, Y87.0).
• There were 4 deaths for which the intent remained undetermined (Y10-Y33).
   

15. Policies directed at reducing drug-induced deaths employ a variety of strategies which can depend on drug type. Information regarding the type of drug(s) in a drug-induced death can be reliant on the availability of an autopsy, toxicology or coronial finding report. When these reports are not available, the drug type may be unknown to the ABS and coded to Other and unspecified drugs, medicaments and biological substances (Unspecified drug) (T50.9). 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.

16. For the 2022 preliminary revision, drug-induced deaths (X40-X44, X60-X64, X85, Y10-Y14) with an associated drug type of Other and unspecified drugs, medicaments and biological substances (T50.9) were in scope for revision.

17. Identification of the specific drug types involved in these deaths, in conjunction with additional drug type information captured for records in scope for revisions to the underlying cause of death (R99, X59.9, Y10-Y34), resulted in the following changes to coroner certified deaths from 2022 preliminary to preliminary revised:

• There was a net decrease of 52 drug-induced deaths where drug type was not specified (T50.9). 
• There was an increase of 541 specified drug types mentioned.
• Benzodiazepines (T42.4) recorded the largest increase with 83 additional mentions.

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 publishing, to reflect the latest available information. A final revision has now been applied to 2020 data, a first revision to 2021 data and a preliminary revision to 2022 data. More information regarding these revisions, including the scope and methodology, can be found in relevant Technical notes in this publication.  

2. As coronial investigations regarding deaths due to suspected suicide can be extensive, it is a cause of death which may be more sensitive to the revisions process. It is important from a public health perspective to have accurate counts of deaths due to suicide. As such, this technical note focusses on how the revisions process has changed counts of death due to suicide in 2020, 2021 and 2022.

3. 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 2020, the final suicide count was 1.4% higher than the preliminary count. 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.

4. In scope for the revisions process is the updating and inclusion of associated causes of death and risk factors as they relate to suicide. This may include coding of more specified substances (drugs) and risk factors such as mental health conditions, chronic diseases and psychosocial factors as they become available in coronial reports on the NCIS. Technical notes on revisions of 2020 and 2021 data (above) contain detailed information on the addition of these associated causes and risk factors through the revisions process.

5. The final number of deaths due to suicide recorded for 2020 is 3,184. This is a net increase of 45 deaths (1.4%) from the preliminary count of 3,139. There was an increase of 57 suicides over the first revision period and a decrease of 12 suicides in the second revision period. 

6. Deaths which have been reassigned to suicide through the revisions process were most likely to be initially coded as:

• 43 deaths were initially coded to Event of undetermined intent (Y10-Y34);  
• 23 deaths were initially coded to Other ill-defined and unspecified causes of mortality (R99);
• 21 deaths were initially coded to Accidental drug poisoning (X40-X44);
• 6 deaths coded to Land transport accident (V01-V89).

7. Deaths initially coded to suicide can at times be reassigned to another intent when coronial investigations are complete and the case closed. Of the deaths reassigned from suicide over the revisions period the majority were reassigned to an Event of undetermined intent (Y10-Y34) or an Accidental drug poisoning (X40-X44). A small number of deaths also had a change in mechanism.
 

8. The revised number of suicides in 2021 is 3,197. This is a net increase of 53 suicides (1.7%) since preliminary coding. There was an increase of 22 suicides over the preliminary revision period and an increase of 31 suicides in the second revision period. Of the deaths identified as suicides through the revisions process:

• 40 deaths were initially coded to Event of undetermined intent (Y10-Y34);
• 25 deaths reassigned from Accidental drug poisoning (X40-X44);
• 25 deaths were initially coded to Other ill-defined and unspecified causes of mortality (R99).
   

9. The preliminary revised number of deaths due to suicide in 2022 is 3,288. This is a net increase of 39 deaths (1.2%) due to suicide. Of these deaths:

• 21 deaths were initially coded to Other ill-defined and unspecified causes of mortality (R99);
• 13 deaths were initially coded to Event of undetermined intent (Y10-Y34);
• 4 deaths were initially coded to Exposure to unspecified factor causing other and unspecified injury (X59).

10. The 2022 reference year will undergo further updates as part of the usual revisions cycle in future. It is anticipated that further improvements and specificity of types of deaths will be captured as part of this process.
 

11. The number and age-standardised death rate of deaths due to intentional self-harm by state and territory from 2013 to 2022 are shown in the Tables 2-7. These tables provide an updated time series that includes the revisions for 2020, 2021 and 2022 and should now be used in preference to those published in September 2023. 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.