Head injuries in Australia 2020–21

The ABS introduced several changes for deaths registered in 2007 and subsequent years (ABS 2009), with the potential to affect injury death statistics.

The most important change was to make 3 data releases for deaths registered in each calendar year:

• preliminary (released a little over one year after the end of the registration year)
• revised (1 year after the preliminary release) and
• final (2 years after the preliminary release).

Further changes were implemented for deaths registered in 2008 and later:

• For both open and closed coroner cases, more time has been spent investigating Part II of the Medical Certificate of Death when information in Part I is not sufficient to allow assignment of a specific UCoD code.
• Increased resources and time have been spent investigating coroners’ reports to identify specific causes of death. This involves making increased use of police reports, toxicology and autopsy reports, and coroners’ findings, to minimise the use of non-specific causes and intents (ABS 2010, 2011b, 2012).
• In the 2019 reference year, there were an additional 2,812 death registrations for Victoria. This issue impacts both the Victorian and national mortality data when reporting by reference year, where 2017, 2018 and 2019 deaths are included. For more detail please refer to Technical note: Victorian additional registrations and time series adjustments in Causes of death, Australia, 2019 (ABS Cat. No. 3303.0).

This issue does not impact on analyses based on year of occurrence of death, which this report is based. Data in this report have not been adjusted for Victorian additional death registrations in 2019.

In this report, deaths registered in 2019 or earlier are based on the final ABS release of cause of death data; deaths registered in 2020 are based on the revised release; and deaths registered in 2021 are based on the preliminary release. Since the preliminary and revised versions are subject to further revision, future reports based on later releases might show different results for the affected years. For further information surrounding the revisions process, see the ABS Causes of Death, Australia, 2021 methodology page.

Deaths data are commonly recorded according to the calendar year in which the death was registered. However, in this report data are presented according to the financial year in which each death occurred, because:

• presenting data by year of occurrence is more meaningful than by year of registration, because some cases are registered much later than when the death occurred (sometimes years later)
• reporting by financial year aligns with AIHW reports on injury morbidity, enabling deaths and hospitalisations to be presented for the same period. 

The following inclusion criteria were used where both of the below resulted in inclusion:

• the multiple cause of death (MCoD) was an external cause code in the range V01–Y36; and
• a multiple cause of death (MCoD) code for a head injury in the range S00–S09, T00.0, T01.0, T02.0, T03.0, T04.0, T06.0, T35.2, T15–T16, T20, T26.

The code range V01–Y36 includes all unintentional (accidental) deaths, intentional self-harm (suicide), homicides, and deaths where intent remained undetermined. The codes provide information around the circumstances of the death, such as details of a transport accident, drowning, asphyxiation, effects of radiation, heat, pressure, deprivation, and maltreatment.

The code range S00–S09, T00.0, T01.0, T02.0, T03.0, T04.0, T06.0, T35.2, T15–T16, T20, T26 includes head injuries (such as fractures, superficial injuries, dislocation, burns and lacerations). The codes also provide information about the single or multiple body regions affected.

The Appendix tables below specify the ICD-10 codes used for each cause category, and describe the inclusions for each major external cause category and the relevant ICD-10-AM codes.

The AIHW uses ‘First Nations people’ to refer to Aboriginal and/or Torres Strait Islander people in this report. The term ‘non-Indigenous Australians’ is used where the NMD explicitly records the persons Indigenous status as non-Indigenous.

First Nations deaths data are reported for 5 jurisdictions—New South Wales, Queensland, Western Australia, South Australia, and the Northern Territory. Other jurisdictions have a small number of First Nations deaths, and identification of First Nations deaths in their registration system is relatively poor, making the data less reliable.

AIHW considers the quality of First Nations identification in deaths data for the 5 jurisdictions to be adequate from 1998 onwards. Data by Indigenous status for this report are for these 5 jurisdictions combined. Deaths data for these 5 should not be assumed to represent the experience in other jurisdictions. Data for these 5 jurisdictions over-represent First Nations populations in less urbanised (more remote) locations.

Since 2015, the Queensland Registry of Births, Deaths and Marriages used both medical certificate information and death registration form information to derive Indigenous status. This approach has been used in South Australia, Western Australia, Tasmania, the Northern Territory, and the Australian Capital Territory since 2007. If either source indicates that the deceased was a First Nations person, they are recorded as such. In New South Wales and Victoria, only information from the death registration form is used (ABS 2020).

The sum of the counts of death by cause may be greater than the total number of injury deaths because some deaths have multiple causes.

Crude/age-specific rates are calculated per 100,000 estimated resident population.

Age-standardised rates are calculated per 100,000 population.

Persons totals include deaths for which sex was not reported.

All age totals include deaths where age is not reported.

Data may be suppressed to maintain the privacy or confidentiality of a person, or because a proportion, rate (numerator or denominator) or other measure is related to a small number of events and may therefore not be reliable. Data may also be suppressed to avoid attribute disclosure. The abbreviation ‘n.p.’ (not published) has been used in tables to denote these suppressions. The suppressed information remains in the totals.

General population

Rates were calculated using, as the denominator, the estimated resident population as at 31 December in the relevant year (for example, 31 December 2018 for 2018–19 data). The final release was used where possible.

Directly age-standardised rates were calculated using the Australian population in 2001 as the standard (ABS 2011a). Age-standardised rates were derived by 5-year age group up to 85+. For counts under 20, age-standardised rates tend to be unstable and so are not presented.

The COVID-19 pandemic and resulting Australian Government closure of the international border from 20 March 2020 caused significant disruptions to the usual Australian population trends. The ERP for 30 June 2020, used in this report reflects these disruptions.

First Nations population

Rates of injury death of First Nations people were calculated using data from 5 jurisdictions (New South Wales, Queensland, Western Australia, South Australia, and the Northern Territory). Data were selected based on place of usual residence.

The assessments of the quality of identification of Indigenous status are affected by restrictions that jurisdictions place on what is included in the data. The assessments are subject to review, and some recent AIHW reports include New South Wales data from 1999 onwards (AIHW 2014).

Rates were calculated using, as the denominator, an estimate of the First Nations population as at December 31 in the relevant year (for example, 31 December 2019 for 2019–20 deaths) using the projected First Nations population, series B (ABS 2019). Rates were not presented for counts under 5 due to unstable rates.

Since estimates of resident First Nations populations are only provided for 30 June, estimates for 31 December are calculated by adding 2 consecutive 30 June estimates and dividing by 2 (for example, the estimate for 31 December 2019 is calculated by adding estimates for 30 June 2019 and 30 June 2020 and dividing by 2).

Directly age-standardised rates were calculated using the Australian population in 2001 as the standard (ABS 2011a). Age-standardised rates were derived by 5-year age group up to 65+. Age-standardised rates were not presented for counts under 20 due to unstable rates.

For non-Indigenous Australians, population denominators were derived by subtracting the estimated First Nations population from the total Australian estimated resident population (of the states and territories eligible for inclusion), as at 31 December of the relevant year.

Current standard practice in AIHW reports is to omit cases where Indigenous status was not stated or unknown.

Rates and change in rates

Estimated trends in age-standardised rates were reported as average annual percentage changes.

The data presented in this report are subject to 2 types of statistical error—non-random and random (a third type of statistical error, sampling error, does not apply in this report, because none of the data sources used involved probability sampling).

Non-random error

Some level of non-random error is to be expected in administrative data collections, such as the NMD on which this report relies. For example, non-random error could occur if the approach to assigning cause codes to deaths were to differ systematically between jurisdictions, or over time. Systems are in place to encourage uniform data collection, and coding and scrutiny of data during analysis include checking for patterns that might reflect non-random error. But some error remains. 

Random error

The values presented in the report are subject to random error, or variation. Variation is relatively large when the case count is small (especially if less than about 10), and small enough to be mostly unimportant when the case count is larger (that is, more than a few tens of cases). 

Some of the topics for which results are reported compare groups that vary widely in case count, largely due to differences in population size (for example, the population of New South Wales is more than 30 times as large as the Northern Territory population, and the population of Major cities is nearly 90 times that of Very remote areas). In this situation, year‑to‑year changes in counts or rates for the smaller-population groups might be subject to large random variation. Such fluctuations could potentially be misinterpreted as meaningful rises or falls. 

Australian Statistical Geography Standard 

The ABS’s Australian Geography Standard (ASGS) Remoteness Structure 2016 (ABS 2016a) is a hierarchical classification system of geographical regions and consists of interrelated structures. The ASGS provides a common framework of statistical geography, and enables the production of statistics that are comparable and can be spatially integrated.

The structure has seven hierarchical levels listed here from smallest to largest:

• Mesh Blocks
• Statistical Area Level 1 (SA1)
• Statistical Area Level 2 (SA2)
• Statistical Area Level 3 (SA3)
• Statistical Area Level 4 (SA4)
• Greater Capital City Statistical Areas
• State and Territory.

Each level directly aggregates to the level above. For example, SA1s are aggregates of Mesh Blocks, and themselves aggregate to SA2s. At each level, the units collectively cover all of Australia.

Remoteness

Australia can be divided into several regions, based on the distance from urban centres. This is considered to predict the range and types of services available. These regions are known as remoteness areas and are defined using the ABS’s ASGS Remoteness Structure 2016 (ABS 2016b). The ASGS Remoteness Structure 2016 categorises geographical areas in Australia into remoteness areas as described at www.abs.gov.au.

Remoteness is an index applicable to any point in Australia, based on road distance from urban centres of 5 sizes. The reported areas are defined as follows:

• Major cities (for example, Sydney, Geelong, Gold Coast)
• Inner regional (for example, Hobart, Ballarat, Coffs Harbour)
• Outer regional (for example, Darwin, Cairns, Coonabarabran)
• Remote (for example, Alice Springs, Broome, Strahan)
• Very remote (for example, Coober Pedy, Longreach, Exmouth).

Data on geographical location of the place of usual residence of the person who died is recorded in the NMD. These data are the state or territory of residence and SA2. Each death is allocated to a remoteness area according to the SA2. 

For more information on the NMD see Deaths data at AIHW

The data quality statements underpinning the NMD can be found in the following ABS publications:

• Australian Bureau of Statistics (2021), Deaths, Australia methodology 
• Australian Bureau of Statistics (2021), Causes of Death, Australia methodology

National Coronial Information System (NCIS)

The NCIS is a data collection which contains information on deaths reported to a coroner in each jurisdiction in Australia and New Zealand. The information contained in the NCIS varies based on the level of detail in the coronial investigation; therefore, the comprehensiveness of the data changes on a case by case basis (NCIS 2022a).

A reportable death is one that is investigated by a coroner, these deaths are generally unexpected or explained. The ABS reported in 2017 that 11.9% of deaths are reportable. Most injury deaths are reportable; with the exception of falls which are commonly doctor certified (NCIS 2022b).

Deaths data are commonly recorded according to the calendar year and month in which the death occurred.

Until the investigation is completed by the coroner and the coding of all relevant fields is completed by the court, the case status remains open in the NCIS. When the investigation and relevant coding is complete, the court changes the case status to closed. At the time of preparing this report, cases from 1 July 2020 to 31 June 2021 were used. Any open cases are excluded from the analysis in this report.

Where the NCIS have reported that a death is due to “intentional self-harm”, the term “suicide” has been substituted to align with broader injury reporting terminology.

Cases were included where:

• the case status was closed
• the case type was due to external cause(s)
• the ICD-10 cause of death variables for a head injury were in the range S00–S09, T00.0, T01.0, T02.0, T03.0, T04.0, T06.0, T35.2, T15–T16, T20, T26
• head-related terminology within the open-text cause of death (COD) fields included ‘head’, ‘skull’, ‘cranium’, ‘face’, ‘scalp’, ‘brain’, ‘nose’, ‘traumatic asphyxia’, ‘hypoxi’, or ‘cerebral’. These were further filtered to remove non-injury related deaths by excluding cases with underlying ICD-10 codes including E05.0,G20,G35,G71.1,G80.0,G93.1, and I69.4.
• the date of death was between 1 July 2020 and 31 June 2021, inclusive.
• the death occurred in an Australian state or territory.

There are six medical cause of death open-text fields provided in the NCIS. Determining the most common terms used in head-injury deaths in the NCIS required the aggregation of all COD fields. Stop words (e.g. and, to, so, for) were removed, as were common words contributing little to the determination of cause of death (e.g. treated, consequence, sustained, history). Leading and trailing spaces were also removed. Each unique search term was counted once per record, regardless of the number of times it appeared in the aggregated cause of death fields.

Related words were transformed to the word root. Words such as ‘fractures’ or ‘fractured’ were substituted with the root ‘fracture’, to ensure complete coverage of a term. Words such as ‘boy’ and ‘man’, or ‘lady’ and ‘woman’ were substituted with ‘male’ and ‘female’ for continuity with the rest of the report. Alternative spellings were streamlined (e.g. haemorrhage and hemorrhage) and small identifiable spelling errors were also corrected (e.g. haemmorrhage).

All haemorrhage and haematoma terms (where the term began with subdural, intracranial, subarachnoid, intracerebral, intracranial, intra cerebral, epidural, extradural, intraparenchymal etc. and ended with haemorrhage or haematoma) were grouped under the umbrella term “intracranial bleeds”. Additionally, the terms “motor vehicle” and “motorcycle vehicle” were grouped under the umbrella term “motor vehicle”.

Case status

Only cases that are closed in the NCIS following coronial investigation are included in this report. It is possible cases of relevance were still under coronial investigation at the time of writing and are excluded from this report.

Quality assessment of closed cases

The NCIS Unit conducts a quality assessment of the coding associated with closed cases. While every effort is made to quality review closed cases in a timely manner, there may be a delay between the case being closed and the completion of the quality review. It cannot be guaranteed that all cases included in this report have been quality assessed.

Primary and secondary mechanism of injury contribution

In the NCIS database, each eligible case is allocated at least one mechanism that explains the means, environmental event, condition or circumstance in which injury was sustained. The first code is known as the primary mechanism of injury. Any secondary code for mechanism of injury is considered to have a secondary contribution to death. For this report, only the primary mechanism of injury was considered for analysis.

The mechanism of injury follows a hierarchical coding structure, including three potential levels of increasing specificity. Level 1 encompasses a broad description of the mechanism. For the purposes of this report, Level 1 codes were referred to as the ‘primary mechanism’. Level 3 codes were referred to as the ‘specific mechanism’.

Primary and secondary object contribution

In the NCIS database, each eligible case is allocated at least one object or substance producing injury code. The first code is known as the primary object or substance producing injury. Any secondary code object or substance producing injury code is considered to have a secondary contribution to death. For this report, only the primary object was considered for analysis.

Cause of death

The NCIS database uses both ICD-10 and medical cause of death data. ICD-10 coding uses the Tenth Revision, and is prepared annually by the ABS for integration into the database. Around 1.2% of cases used in this report do not have any ICD-10 code recorded.

Medical cause of death is determined by the investigating forensic pathologist. The medical cause of death open-text fields are not subject to standardised terminology or review, which may influence the identification of cases due to misspellings, or alternative descriptions not considered within the scope of this report.

Data are presented as counts. Persons totals include deaths for which sex was not reported. All age totals include deaths where age is not reported. A value of 0 indicates that no deaths were identified. To ensure data are appropriately de-identified, values between 1–4 were suppressed. The suppressed information remains in the totals.

For more information on the NCIS see NCIS about the data.

ABS (Australian Bureau of Statistics) 2009. Causes of death, Australia, 2007. ABS cat. no. 3303.0. Canberra: ABS.

ABS 2010. Causes of death, Australia, 2008. ABS cat. no. 3303.0. Canberra: ABS.

ABS 2011a. Australian demographic statistics, June 2011. ABS cat. no. 3101.0. Canberra: ABS.

ABS 2011b. Causes of death, Australia, 2009. ABS cat. no. 3303.0. Canberra: ABS.

ABS 2012. Causes of death, Australia, 2010. ABS cat. no. 3303.0. Canberra: ABS.

ABS 2016a. Australian Statistical Geography Standard (ASGS): Volume 1—Main structure and greater capital city statistical areas, July 2016. ABS cat. no. 1270.0.55.001. Canberra: ABS.

ABS 2016b. Australian Statistical Geography Standard (ASGS): Volume 5—Remoteness structure, July 2016. ABS cat. no. 1270.0.55.005. Canberra: ABS.

ABS 2019. Estimates and projections, Aboriginal and Torres Strait Islander Australians, 2006 to 2031. ABS cat. no. 3238.0. Canberra: ABS.

ABS 2020. Causes of death, Australia methodology. Canberra: ABS. Viewed 9 November 2021.

ABS 2021. Causes of death, Australia methodology. Canberra: ABS. Viewed 19 May 2022.

AIHW (Australian Institute of Health and Welfare) 2014. Mortality and life expectancy of Indigenous Australians: 2008 to 2012. Cat. no. IHW 140. Canberra: AIHW.

AIHW: Harrison JE & Henley G 2015. Injury deaths data, Australia: technical report on issues associated with reporting for reference years 1999–2010. Injury research and statistics series no. 94. Cat. no. INJCAT 170. Canberra: AIHW.

AIHW: Henley G & Harrison J 2009. Injury deaths, Australia 2004–05. Injury research and statistics series no. 51. Cat. no. INJCAT 127. Canberra: AIHW.

AIHW: Henley G & Harrison JE 2015. Trends in injury deaths, Australia: 1999–00 to 2009–10. Injury research and statistics series no. 74. Cat. no. INJCAT 150. Canberra: AIHW.

AIHW: Henley G & Harrison JE 2019. Trends in injury deaths, Australia: 1999–00 to 2016–17. Injury research and statistics series no. 127. Cat. no. INJCAT 207. Canberra: AIHW.

Kreisfeld R & Harrison J. 2005. Injury deaths, Australia, 1999. Injury research and statistics series no. 24. Cat. no. INJCAT 67. Canberra: AIHW.

National Coronial Information System (NCIS) (2020) ‘NCIS Data Dictionary’, NCIS, Victorian Government, accessed 31 August 2022.

NCIS (2022a) Data sources, NCIS, accessed 31 August 2022. 

NCIS (2022b) Explanatory notes, NCIS, accessed 31 August 2022. 

WHO (World Health Organization) 2019. The international statistical classification of diseases and related health problems, 10th revision (ICD-10). Geneva: WHO. Viewed 9 November 2021.