Australian Institute of Health and Welfare (2022) Serving and ex-serving Australian Defence Force members who have served since 1985: suicide monitoring 1997 to 2020, AIHW, Australian Government, accessed 31 January 2023.
Australian Institute of Health and Welfare. (2022). Serving and ex-serving Australian Defence Force members who have served since 1985: suicide monitoring 1997 to 2020. Retrieved from https://www.aihw.gov.au/reports/veterans/serving-and-ex-serving-adf-suicide-monitoring-2022
Serving and ex-serving Australian Defence Force members who have served since 1985: suicide monitoring 1997 to 2020. Australian Institute of Health and Welfare, 16 November 2022, https://www.aihw.gov.au/reports/veterans/serving-and-ex-serving-adf-suicide-monitoring-2022
Australian Institute of Health and Welfare. Serving and ex-serving Australian Defence Force members who have served since 1985: suicide monitoring 1997 to 2020 [Internet]. Canberra: Australian Institute of Health and Welfare, 2022 [cited 2023 Jan. 31]. Available from: https://www.aihw.gov.au/reports/veterans/serving-and-ex-serving-adf-suicide-monitoring-2022
Australian Institute of Health and Welfare (AIHW) 2022, Serving and ex-serving Australian Defence Force members who have served since 1985: suicide monitoring 1997 to 2020, viewed 31 January 2023, https://www.aihw.gov.au/reports/veterans/serving-and-ex-serving-adf-suicide-monitoring-2022
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Suicide monitoring by survival modelling with reason for separation: 2003–2020
Cox proportional hazards modelling was carried out to see which service-related factors were most strongly associated with suicide death in the ex-serving ADF population over time when all other available factors are accounted for.
Results show that the following service-related characteristics were associated with significantly higher or lower instantaneous rates (meaning the rates at any instant) of suicide among the ex-serving population, holding all other available factors constant:
These results indicate that the rate of suicide is lower in those who are over 50 years of age, female, commissioned officers, have served for 10 or more years, and left voluntarily.
While these results can identify groups of people who have a higher rate of suicide, they cannot indicate if any specific characteristic is the reason for a suicide death. There is limited data on the sequencing of factors/exposures that can contribute to suicide death. Qualitative analysis methods may provide insight into the circumstances leading up to suicide death.
The 2021 suicide monitoring report, Serving and ex-serving Australian Defence Force members who have served since 1985: suicide monitoring 2001 to 2019, and the analyses of the previous chapters, used univariate analysis to report the rates of suicide. This approach is somewhat limited in that the different variables must be looked at in isolation.
In this chapter Cox proportional hazards modelling is used to identify and compare interactions between variables. This multi-factor analysis compliments the trends and conclusions observed above or in previous reports, providing further insight into the factors associated with suicide while independently confirming previous analyses.
Cox proportional hazard modelling was used to perform survival modelling analyses where the occurrence of suicide was monitored once an individual has separated from the ADF. Since separation from the ADF marks the entry of an individual into this model it does not account for permanent or reserve members, only ex-serving. See the Technical notes for a deeper discussion of this technique.
Two models are presented, the first for ex-serving members who separated on or after 01 January 1997, while analysing the variables: age group, sex, rank, service, and length of service.
The second model contains all ex-serving members who separated on or after 01 January 2003 and will assess reason for separation alongside: age group, sex, rank, and length of service. This model is interested specifically in reason for separation, so the monitoring period was restricted the post-2003 cohort (which has accurate separation data).
Note that senior and junior other ranks were merged into an “other ranks” category and length of service groups were aggregated into <1, 1-10, and 10 or more groups. This was done to maximise the population numbers within these subgroups, for more robust statistical analyses.
Also note that the distinction between permanent ex-serving and reserve ex-serving did not satisfy the proportional hazards assumption (see Box 3), as the suicide rates for these cohorts get closer together with time. Therefore, this could not be included.
The modelling results are expressed as hazard ratios (HR), which in this context represents the multiplicative difference in instantaneous rate of suicide between two groups within a variable while holding all other analysed variables constant. Groups within a variable are compared to a reference group which was nominated to be the most populous subgroup for each variable. Hazard ratios are assumed to be constant over time (this is the proportional hazards assumption) and variables for which this is not so are excluded.
To elaborate, for two groups within a variable, Group A and Group B, where Group A is the reference group, and Group B is the study group, if the HR = 2, this can be interpreted as: individuals in Group B have double the rate of death by suicide at every instant compared to individuals in Group A at any given time over the course of the model, holding all other analysed covariates constant. HRs are multiplicative across the model variables.
At any point during the monitoring period:
The 95% confidence intervals (CI) for each HR are provided where HRs are considered significant difference to the reference group if the 95% CI does not contain the value 1.
This analysis contains all ex-serving members of the ADF who separated on or after 01 January 1997 and models the rate of suicide over time across the variables:
Time since separation is excluded since it represents the time variable of the model itself (measuring the time between separation from the ADF and death by suicide). As such it cannot be included for analysis.
The reference groups for comparison were selected to be those that were most populous within each variable over the model period. These were 30-39 years of age, male, ranks other than officer, Army, and 10 or more years length of service.
While holding all other analysed variables constant, the instantaneous rate of suicide in the ex-serving population at any point between 1997-2020 was:
Service was not found to be a statistically significant predictor of suicide once all other factors were controlled for. The model outputs are given in full in Table 11, and Figure 18 below.
Source: AIHW analysis of linked Defence historical personnel data–PMKeyS–NDI data 1985–2020.
This analysis contains all ex-serving members of the ADF who separated on or after 01 January 2003, and models rate of suicide over time across the variables:
The reference groups for comparison were again selected to be those that were most populous over the model period within each variable. These were 30-39 years of age, male, ranks other than officer, voluntary separation, and 10 or more years length of service. Since this model contains fewer people than the 1997-2020 one, results for variables other than reason for separation should not be taken as more meaningful here. For example, there is insufficient evidence to conclude that the introduction of reason for separation as a variable renders age no longer significant.
While holding all other analysed variables constant, the rate of suicide for people who separated from the ADF for involuntary medical reasons at any point between 2003-2020 is 2.8 times compared to those separated voluntarily.
These results are given in detail below (see Table 12 and Figure 19).
Source:AIHW analysis of linked Defence historical personnel data–PMKeyS–NDI data 1985–2020.
This result confirms that involuntary medical separation is a significant risk factor for suicide even when accounting for the other model variables.
Data underlying this graph are available in Supplementary table S8.1-S8.6. See Data for a link to the tables.
Please note, data for more recent years are subject to change; see the Technical notes for further detail.
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Some readers may find parts of this content confronting or distressing.
Please carefully consider your needs when reading the following information about suicide. This report contains information on numbers and rates of death by suicide for serving and ex-serving members of the ADF. This report may be distressing to some readers.
If this material raises concerns for you, support is available. Please contact Lifeline on 13 11 14, or Defence All-hours Support Line on 1800 628 036, or Open Arms - Veterans and Families Counselling, available free of charge, 24 hours a day, 7 days a week, or see other ways you can seek help.
The information included here places an emphasis on data, and as such, can appear to depersonalise the pain and loss behind the statistics. The AIHW acknowledges the individuals, families and communities affected by ADF member and veteran suicide each year in Australia.
The AIHW supports the use of the Mindframe guidelines on responsible, accurate and safe suicide and self-harm reporting. Please consider these guidelines when reporting on statistics on the monitoring of suicide and self-harm.
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