Serving and ex-serving Australian Defence Force members: suicide monitoring 1997 to 2023

Changes to previously published suicide information

An additional 77 suicide deaths are included in this report compared with the 2024 report: Serving and ex-serving Australian Defence Force members who have served since 1985: suicide monitoring 1997 to 2022. The changes in the number of included suicide deaths are as follows:

• 73 suicide deaths that occurred in 2023
• due to a lag in reporting cause of death and updates to the National Death Index (NDI):
  • 8 additional suicides deaths in 2022 (6) and 2021 (2)
  • 4 less suicide deaths in 2021 (2) and 2020 (2)

Care should be taken when comparing data in this report with previous AIHW reports due to changes in the monitoring period and study cohort. It is more useful to focus on suicide rates than counts, as these give a better indication of suicide risk for different groups within the ADF population.

In addition to the inclusion of the new year of cause of death data, there are 3 main reasons for changes to previously published data on deaths by suicide, as described below.

Lag in cause of death information

Analysis in this study is based on year of death. The NDI is the source of information on fact of death. Fact of death information from the NDI is supplemented with cause of death information from the National Mortality Database (NMD). Analysis of the NMD for all Australian deaths shows that between 4% and 7% of deaths are not registered until the following year (ABS 2018). These deaths are not captured in cause of death information until data for the following year becomes available. Consequently, there are usually a small number of suicides in each report that should have been in the prior year’s data but were only confirmed after the report was published.

Cause of death data revisions (ABS)

In this report, cause of death information is based on final cause of death information for the years 1997 to 2020. Revised data are used for 2021, and preliminary data are used for 2022 and 2023. Cause of death for a small number of records linked to revised and preliminary cause of death data may change where a death is being investigated by a coroner and more up-to-date information becomes available from the ABS revisions process. This may have a small effect on the number of deaths attributed to suicide in these years, as some deaths currently coded as ‘undetermined intent’ could later be identified as ‘intentional self-harm’ (or vice versa).

Although this method likely captures the vast majority of deaths by suicide, there is potential for some to be missed if coronial findings take longer than 4 years to deliver and the coronial finding results in an update to the cause of death.

Care needs to be taken when interpreting data derived from deaths registered in Victoria. Following investigations by the ABS and the Victorian Registry of Births, Deaths and Marriages, 2,812 additional death registrations from 2017, 2018 and 2019 were identified that had not previously been provided to the ABS. A time series adjustment has been applied to these deaths to enable a more accurate comparison of mortality over time. Affected deaths are presented in the year in which they were registered (that is, removed from 2020 and added to 2018 or 2019). For detailed information on this issue please refer to Technical note: Victorian additional registrations and time series adjustments in Causes of death, Australia (ABS cat. no. 3303.0) available from the ABS website.

Improvements in information available to the study

Changes to previously published results may also occur as additional information becomes available for study.

For example, differences in data collection methods and policy regarding the timing of death registration can affect when and how the data is recorded in the ABS collection. Data users should note the potential impact of these changes when making comparisons between reference periods. While such changes will not explain all differences between years, they are a factor that may influence the magnitude of any changes in suicide numbers as revisions are applied (ABS 2018).

Improvements in available information and linkage processes over time have also resulted in additional suicides being identified for previous reporting periods.

Australian Bureau of Statistics (ABS) changes to mortality coding over the study period

The following information on mortality coding is sourced from the ABS. For further information, see the ABS Causes of death, Australia report (ABS 2018).

Substantial changes to ABS coding of cause of death data were undertaken in 2006, which improved data quality by enabling the revision of cause of death for open coroner’s cases over time. Deaths that are referred to a coroner (including deaths by suicide) can take time to be fully investigated. Accordingly, all coroner-certified deaths registered after 1 January 2006 are subject to a revisions process. This allows cause of death for open coroner’s cases to be included at a later time (where the case is closed during the revision period). Cause of death data are deemed preliminary when first published. The revised and final versions of the data are typically published 12 and 24 months after initial processing respectively. Revisions did not take place between 2001 and 2005. Consequently, the ABS recognises that deaths by suicide may have been under-reported during this period (ABS 2018).

In addition to the aforementioned changes, new coding guidelines were applied to deaths registered from 1 January 2007. The new guidelines improve data quality by enabling deaths to be coded as suicide by ABS mortality coders if evidence from police reports, toxicology reports, autopsy reports, and coroners’ findings indicate that the death was due to suicide. Previously, coding rules required a coroner to determine a death as due to suicide for it to be coded as suicide.

The combined result of both changes has been the more complete identification of deaths by suicide, and a reduced number of deaths coded as ‘undetermined intent’, within Australian mortality data. The National Coronial Information System (NCIS) also continually makes improvements and enhancements to their system which allows for ABS coding to be accessed in a timelier fashion.

Detailed information on coding guidelines for intentional self-harm, and administrative and system changes that can have an impact on the mortality data set, can be found in Explanatory Notes 91-100 of Causes of death, Australia report (ABS 2018).