Comparing suicide rates 2002 to 2017

There are differences between the demographic profiles of the three Australian Defence Force (ADF) service status groups and the Australian population (Box 4). Because of these differences, comparisons of numbers of suicides between the ADF service status groups and the Australian population are not straightforward. To assist in making comparisons, this report presents rates of suicide and Standardised Mortality Ratios (SMRs).

Box 4: Differences between the ADF and Australian populations

The age and sex profiles of the ADF service status groups and the Australian population differ. The comparative Australian population is older on average and around 50% male, while the ADF service status groups are younger and around 85% male. These age and sex differences need to be accounted for when examining differences in suicide levels between these populations.

Further, the annual population size for each of the service status groups differs. While the serving and reserve populations are relatively stable over time, the ex-serving population in this study started at zero (0) on 1 January 2001 and increases each year as personnel discharge. Unlike the serving and reserve populations, the ex-serving population is also ageing over time.

Suicide rates complement information on the number of suicide deaths by taking into account the size of the underlying population, to provide information on how often suicide death occurs in that population.

This report uses SMRs to control for the difference in age structures between the three ADF service status groups and its equivalent comparison (Australian) population. SMRs are presented as comparisons of age-adjusted rates.

Distinct comparison populations were used for each ADF service status group. Lower and upper ages were defined by ages observed within each ADF service status group.

Data for 2001 are not included in the calculation of rates in this report, as data for the serving and reserve populations were not available before 2002 due to a change in Defence personnel management systems at that time. Analysis of ex-serving personnel was restricted to data from 2002 onwards, in line with reporting for serving and reserve groups.For information on interpreting these results, including changes to previously published data, see Box 3 and the Technical Notes.

Analysis 2002 to 2017

Suicide rates were calculated for the period 2002 to 2017 for each service group. These rates can be validly compared with each other and can be compared with rates for the Australian population. Due to the small number of suicide deaths among women across the ADF service status groups it was only possible to present the suicide rate for ex-serving women. The suicide rates for 2002-2017 are shown in Table 3.

Table 3. Suicide rates for 2002-2017, ADF service groups, men and women

Service Group

Suicide Rate for Men (per 100,000 population)

Suicide Rate for Women (per 100,000 population)

Serving

12

n.p.

Reserve

12

n.p.

Ex-serving

27

15

n.p.   Not published because of small numbers, confidentiality or other concerns about the quality of the data.Source: AIHW analysis of linked PMKeyS—NDI data 2001–2017.

SMRs were also calculated for the period 2002-2017 to control for differences in age distributions between the ADF and Australian populations. For more information about SMRs see Age-adjusted suicide measures (standardised mortality ratios) by service status (men).

The age-adjusted rate of suicide, when compared to the Australian population was:

  • 48% lower for serving men, SMR = 0.52 (95% CI = 0.42-0.64)
  • 48% lower for men in the reserves, SMR = 0.52 (95% CI = 0.41-0.66)
  • 18% higher for ex-serving men, SMR = 1.18 (95% CI = 1.02-1.35)
  • 115% (or 2.15 times) higher for ex-serving women, SMR = 2.15 (95% CI = 1.33-3.29).

These differences were all found to be statistically significant.

Unlike suicide rates, these SMRs cannot be used to compare suicide rates between service groups or across time.

Suicide rate for females

While the number of women in the ADF is increasing, it has historically been low. The size of the contemporary female ex-serving cohort is increasing each year, with the number reaching 16,366 in 2017. Each year of data adds to the confidence in the results for female ex-serving ADF personnel. For this reason, suicide information for ex-serving females is reported for the first time in this report.

In the period 2001-2017, there were 21 suicide deaths among ex-serving females.

The suicide rate for ex-serving females in 2002-2017 was 15 per 100,000 compared with 27 per 100,000 for males as shown in Table 3.

The age-adjusted rate of suicide for ex-serving females was 115% (or 2.15 times) higher than Australian women, SMR = 2.15 (95% CI = 1.33-3.29).

This difference was statistically significant. Confidence intervals (CI) provide one way to assess the randomness that may occur in the number of suicides over time. The wider confidence interval for the female ex-serving SMR reflects the higher degree of potential variability compared to the male results. More information on confidence intervals is provided in the Technical Notes section.

For privacy and statistical reasons relating to the small number of women in the study, suicide rates and SMRs for serving and reserve women and SMRs for ex-serving women by 3-year periods are not reported.

Analysis by period 2007 to 2017

Rate of suicide by service status (men)

Observed rates for the three ADF service status groups are presented in this section. They can be validly compared with each other and over time, and can be compared with rates for the Australian population.

Description: This section reports the observed suicide rates for men in the three ADF service status groups, for 3-year rolling aggregations from 2007 to 2017. Comparisons are made between rates for men in each of the service status groups and to rates for Australian men in the same age range.

While the proportion of women in the ADF is increasing, the number of women serving in the ADF has historically been low, and for privacy and statistical reasons, only limited rates for ADF women have been reported. For further information on interpreting this measure, see Technical Notes.

Results based on cause of death information that is not final are subject to greater change than those based on final cause of death information. However, estimates for all periods are subject to change as improvements to the underlying data are incorporated.

For the 3 year rolling aggregations from 2007 to 2017, the rate of suicide among:

  • serving men was between 8 and 18 per 100,000 population
  • men in the reserves was between 10 and 15 per 100,000 population
  • ex-serving men was between 25 and 33 per 100,000 population.

Significance testing using confidence intervals (CIs) has been used to examine the differences between groups. See Technical Notes and Data tables for more detail.

Over the study period, the suicide rate among serving men was consistently lower than the rate for Australian men in the same age range. This difference was found to be statistically significant for each 3-year period up to and including 2014–2016.

For men in the reserves, the suicide rate was consistently lower than the rate for Australian men over the study period. This difference was found to be statistically significant for the most recent 3-year periods from 2013–2015 to 2015–2017.

For ex-serving men, the suicide rate was consistently higher than that for men in the Australian population. This difference was found to be significantly higher for the 3-year period 2013–2015 and the subsequent 3-year period 2014–2016.

The interactive graph below presents the suicide rates for men in each of the three ADF service status groups and the rates for the comparative population of Australian men, for all 3-year periods from 2007-2009 to 2015-2017.

Data underlying this graph are available in Supplementary tables S1.1 to S1.3. See Data for a link to the tables.

Please note, data are subject to change: see Technical Notes for further detail.

Age-adjusted suicide measures (standardised mortality ratios) by service status (men)

This report uses SMRs to control for the difference in age structures between the three ADF service status groups and their equivalent comparison (Australian) population. SMRs for men are presented by service status, for 3-year periods from 2007 to 2017.

Description:  SMRs provide a comparison of suicide rates between two populations, while controlling for differences in age distributions. SMRs greater than 1.0 indicate age and sex-specific rates are higher in the ADF population than those in the Australian population; and SMRs less than 1.0 indicate lower rates in the ADF population. SMRs are presented as comparisons of age-adjusted rates.

SMRs cannot be compared with each other, because different weighting is used to generate each result.

While the proportion of women in the ADF is increasing, the number of women serving in the ADF has historically been low, and for privacy and statistical reasons, only the suicide rate and SMR for ex-serving women for the period 2002–2017 has been reported.

For further information on interpreting this measure, see Technical Notes. Results based on cause of death information that is not final are subject to greater change than those based on final cause of death information. However, estimates for all periods are subject to change as improvements to the underlying data are incorporated.

The age-adjusted suicide rate among ex-serving men was consistently higher than in men in the Australian population over the whole study period. A significant difference was observed in the 3-year period 2013–2015 (see Data tables for more detail). When compared with the rate for Australian men, the age-adjusted rate for ex-serving men was between 14% higher (SMR = 1.14) in 2009–2011 and 36% higher (SMR = 1.36) in 2013–2015.

After adjusting for age, the suicide rate for men in the reserves was consistently lower than the Australian population. When tested, this difference was found to be statistically significant in each 3-year period from 2009–2011 to 2015–2017. When compared with rates for Australian men, the age-adjusted suicide rate among men in the reserves ranged from 32% lower (SMR=0.68) in 2007–2009 to 55% lower (SMR=0.45) in 2013–2015 and 2015–2017.

After adjusting for age, the suicide rate for serving men was consistently lower when compared with rates for Australian men in each 3-year period between 2007–2009 and 2015–2017. The age-adjusted suicide rate for serving men was found to be significantly lower than rates for Australian men in each 3-year period from 2007–2009 to 2014–2016. When compared to rates for Australian men, the age-adjusted suicide rate for serving men ranged between 63% lower (SMR=0.37) in 2012–2014 and 24% lower (SMR=0.76) in 2015–2017.

The SMRs for men in each ADF service status group between 2007–2009 and 2015–2017 are presented in the interactive graph below. Select an ADF service group from the menu to display its SMR.

Data underlying this graph are available in Supplementary tables S2.2 to S2.4. See Data for a link to the tables.

Please note, data are subject to change: see Technical Notes for further detail.

Suicide rates by age (ex-serving men, aged under 30 and aged 30 years and over)

Description: This section presents suicide rates per 100,000 population for ex-serving men aged under 30 and those aged 30 years and over, for 3-year periods from 2007 to 2017. Comparisons are made to rates for men in the same age range in the Australian population.

While the proportion of women in the ADF is increasing, the number of women serving in the ADF has historically been low, and for privacy and statistical reasons, suicide rates for ADF women are not reported. For further information on interpreting this measure, see Technical Notes.

Results based on cause of death information that is not final are subject to greater change than those based on final cause of death information. However, estimates for all periods are subject to change as improvements to the underlying data are incorporated.

From 2007–2009 to 2015–2017 the suicide rate for ex-serving men aged under 30 was consistently higher than that for men in the same age range in the Australian population. When tested, the difference was significant from 2012–2014 to 2014–2016. The suicide rate for ex-serving men aged under 30 was 23 per 100,000 at the start of the study period and 47 per 100,000 in 2013–2015. The rate for all Australian men under 30 was between 17 and 21 per 100,000 over the study period.

The suicide rate for ex-serving men aged 30 years and over ranged between 23 and 29 per 100,000 population over the study period. During this time, there was no evidence of a difference in suicide rates between ex-serving men aged 30 and over and men in the same age range in the Australian population.

The suicide rate for ex-serving men, by age, is compared with the rate for Australian men in the same age range in the interactive graph below. Select an age group from the menu to display the comparison.

Data underlying this graph are available in Supplementary tables S3.1 to S3.2. See Data for a link to the tables.

Please note, data are subject to change: see Technical Notes for further detail.

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