Appendix A: Data information and issues

This appendix provides information on the data used in the report, and on issues relevant to interpreting the data. Further information on Australian injury death data for 1999–2010 has previously been reported (AIHW: Harrison & Henley 2015).

Injury deaths data

Most data in this report on fatal injuries are from the NMD. This database comprises CODURF data, which are provided to the AIHW by the state and territory registries of births, deaths and marriages and the NCIS, and are coded by the ABS.

Data are presented according to the financial year in which each death occurred, rather than the calendar year in which the death was registered, for 2 reasons:

  • Presenting data by year of occurrence provides a more meaningful interpretation of data in comparison to presenting data by year of registration, where cases can be registered at a time significantly later (in some cases years later) than when death occurred.
  • Reporting by financial year is in line with AIHW reports on injury morbidity, enabling deaths and hospitalisations to be compared for the same period.

Records that met the following criteria were included in this report:

  • deaths that occurred on 1 July 1999 to 30 June 2017, and had been registered by 31 December 2017; and
  • the UCoD was an external cause code in the range V01–Y36; or
  • at least 1 MCoD was an external cause code in the range V01–Y36, and at least 1 other MCoD was a code for injury (S00–T75 or T79).

The codes are from the WHO ICD-10 (WHO 2016). The external cause codes are from Chapter XX External causes of morbidity and mortality, and the injury codes are from Chapter XIX Injury, poisoning and certain other consequences of external causes.

Box A.1: Multiple causes of death (MCoD)

Box 1.1 provided standard definitions of the terms underlying cause of death (UCoD) and multiple causes of death (MCoD) codes.

MCoD codes in this report relate to the causes of death that contributed to death and may or may not have been related to the underlying cause.

For example, an elderly person might fall and fracture their hip. This person’s advanced age, frailty, and perhaps other comorbid conditions might limit their capacity to tolerate injury, leading to their death. In this instance, this record would most likely be assigned an UCoD of an external cause code for fall (W00–W19) and a MCoD code for hip injury (S72).

In another example, an elderly person might suffer a heart attack that results in a fall, and subsequently a hip fracture. As with the first example, a combination of factors might lead to death. In this instance, this record would most likely be assigned an UCoD code for acute myocardial infarction (I21), a MCoD of an external cause code for fall (W00–W19), and a MCoD code for hip injury (S72).

Both of these cases would be included in this report, because the first example meets the second of the criterion, while the second example meets the third criterion.

Supplementary data sources

For some external causes of injury, trends in age-standardised rates over time calculated using NMD mortality data have been compared with trends in rates calculated using supplementary sources of mortality data.

These comparisons were made for external causes shown in previous work to have been significantly affected by problems relating to classification (see ‘Coding of deaths data’ in this appendix).

Transport-related injury

Rates for deaths due to unintentional transport-related injury calculated using NMD mortality data were compared with rates calculated using data extracted from the Australian Road Deaths Database in March 2019, available from the website of the Bureau of Infrastructure, Transport and Regional Economics (BITRE 2019). This website provides data on road deaths, but not total transport injury.

The number of transport deaths for each financial year was estimated by multiplying the recorded number of road deaths by a factor obtained by dividing the number of transport deaths in the NMD data by the number of deaths occurring in traffic (on-road) deaths in the NMD data for each data year.

Drowning

Rates for deaths involving unintentional drowning were compared with rates calculated using data extracted online from the NCIS,  as at March 2019, as well as rates calculated using data extracted from national drowning reports published by the Royal Life Saving Society of Australia.

Data were downloaded from the NCIS website, and duplicate records (that is, records with matching NCIS numbers) were removed before analysis.

Table A.1 provides the criteria used to select drowning-related deaths.

Table A.1: Inclusion and exclusion criteria for drowning-related cases extracted from the NCIS website

Criteria for inclusion Criteria for exclusion

Case type(a) notification or case type completion) = Death due to external cause(s)
and

Mechanism level 2 = Drowning/near drowning.

Case type completion = Death due to natural cause(s)
or

Intent at completion = Intentional self-harm, Assault, Legal intervention,
Operations of war, civil conflict and acts of terrorism, or Complications of medical or surgical care
.

Note:  

  1. Case type indicates whether a death was due to natural, external, or unknown causes, or the body was never recovered.

Suicide

Rates for deaths due to suicides calculated using NMD mortality data were compared with rates calculated using data extracted online from the NCIS, as at March 2019. Data were downloaded from the NCIS website, and duplicate records (that is, records with matching NCIS numbers) were removed before analysis.

Table A.2 provides the criteria for selecting suicide deaths.

Table A.2: Inclusion and exclusion criteria for suicide cases extracted from the NCIS website

Criteria for inclusion Criteria for exclusion

Case type(a) notification or case type completion) = Death due to external cause(s)
and

Intent notification or intent completion = Intentional self-harm)

or

Activity code level 2 = Self-inflicted harm.

Case type completion = Death due to natural cause(s)
or

Intent completion = Unintentional, Assault, Legal intervention,
Operations of war, civil conflict and acts of terrorism, or Complications of medical or surgical care
.

Note: 

  1. Case type indicates whether a death was due to natural, external, or unknown causes, or the body was never recovered.

Homicide

Rates for deaths due to homicides calculated using NMD mortality data were compared with rates calculated using case data extracted from the AIC National Homicide Monitoring Program annual reports and from reports of the ABS series Recorded crime—victims (ABS 2000–2017a).

Coding of deaths data

The ABS obtains deaths registration data from the state and territory death registers, which, in turn, obtain information from the doctor or coroner who certifies each death.

The ABS codes causes of death according to the ICD-10 and, after de-identification, creates the CODURF. Most of the coding is done using an automated coding system.

If a death was due to an injury, the ICD-10 requires coding of the ‘external cause’ of the injury, such as a car crash of a particular type as the UCoD. Most injury deaths are certified by a coroner. For these deaths, the ABS seeks additional information required to code external causes from the NCIS.

Some injury deaths, and most deaths from other causes, are certified by a medical practitioner. In these instances, ABS coders rely on information about causes of death that was entered onto the death certificate. Of the deaths included in this report, the most common type of injury in doctor-certified deaths is ‘fall’.

The result of this process is a record in an annual ABS mortality data file that summarises characteristics of the person who died (for example, age, sex, and Indigenous status), and characteristics of his or her death (for example, causes, date, and place where the person usually lived).

Certain aspects of the method used by the ABS have differed according to the registration year of deaths during the period covered by this report. The reasons for making the changes and their nature have been reported by the ABS (ABS 2009). The changes are described in this appendix because of their potential to affect injury death statistics, including those in this report.

Changes in death registrations over time

Deaths registered to end of 2005

  • Each death was assessed within about 1 year after the end of the year in which it was registered.
  • For most injury deaths, coronial investigation had ended, and information was available through NCIS by the ABS’s cut-off date.
  • But for some injury deaths, information was lacking in the NCIS when the death was assessed. This could occur if a coroner was still investigating the death, or if information about it had not been entered into the NCIS.
  • The cause code assigned sometimes differed importantly from the cause code that would have been assigned had the data in NCIS been complete when the ABS ceased coding an annual set of data to finalise the file for reporting and release. Deaths due to suicide and homicide were most affected, because the records for these causes tend to take longer than others to be finalised in NCIS.
  • It has been found that suicide deaths were under-counted in the ABS cause-of-death data for 2004 (AIHW: Harrison et al. 2009), and transport-related deaths were under-counted for 2004–05 (AIHW: Henley & Harrison 2009).

Deaths registered in 2006

  • The initial version, released in 2008, was affected in much the same way as the file of deaths registered in 2005.
  • The ABS made a second release of this file in 2012, coded on the basis of information that was in the NCIS by 2011, and applied like those described in the next section (ABS 2012a).
  • The second release file of 2006 registrations was used in this project.

Deaths registered in 2007–2017

  • The ABS introduced several changes in response to the problems outlined in the previous section, which have been applied to deaths registered in 2007 and subsequent years (ABS 2009).
  • The most important change was to make 3 releases of the data concerning deaths registered in each calendar year: preliminary (released a little over 1 year after the end of the registration year), revised (1 year after that), and final (2 years after preliminary).
  • Further changes were implemented by the ABS 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.
  • Also, increased resources have been used, and more time spent investigating coroners’ reports to identify specific causes of death. This involved making increased use of police reports, toxicology reports, autopsy reports, and coroners’ findings for both open and closed cases, to minimise the use of non-specific causes and intents (ABS 2010a, 2011, 2012a).

In this report, Final release data have been used for deaths registered in 2007–2014, Revised release data have been used for deaths registered in 2015, and Preliminary release data have been used for deaths registered in 2016 and 2017, which were the latest data available at the time of analysis.

Due to the multiple release process, future reports based on later releases of cause-of-death data might show different results to those presented in this report.

The ABS revision process will have no more than a very small effect on the data for years of death up to and including 2013–14 (Table A.3). By contrast, all of the cases reported that have year of death of 2016–17 and 2015–16, and 58% of those with year of death 2014–15, were based on Preliminary or Revised CODURF releases. Re-analysis of deaths data for those periods when final CODURF releases are available can be expected to produce different results.

Table A3: Injury deaths, by ABS CODURF release and financial year of death

 

Financial year of death

ABS CODURF release
Preliminary (%) Revised (%) Final (%)
2016–17

100.0

0.0

0.0

2015–16 55.9 44.1 0.0
2014–15 0.5 57.5 42.0
2013–14 0.2 0.3 99.5
1999–00 to 2010–11 <0.1 <0.1 99.9

Appendix C compares counts for Preliminary, Revised and Final releases of CODURF data for all injury deaths, and for some external causes of injury.

Further information on effects of the matters discussed in this section on estimates of injury mortality for 1999–2010 has previously been reported (AIHW: Harrison & Henley 2015; AIHW: Henley & Harrison 2015).