Research identifies the population groups disproportionately impacted by suicide in Australia

Attributable risk of suicide for populations in Australia

By Piumee Bandara, Andrew Page, Lennart Reifels, Karolina Krysinska, Karl Andriessen, Marisa Schlichthorst, Anna Flego, Long Khanh-Dao Le, Cathrine Mihalopoulos, Jane Pirkis.

Published 8 January 2024

What's the issue?

Suicide is a recognised public health issue in Australia that significantly impacts individuals, families and communities. Identification of populations that are disproportionately impacted by suicide can inform the approach of the Australian government, health systems and community to suicide prevention.

The population attributable fraction (PAF) is one way to determine which populations are disproportionately impacted by suicide.

The PAF estimates the proportion of cases of a particular health issue (e.g. suicide) that would be prevented if the effects of certain risk factors were comprehensively addressed.

The PAF takes into account both the relative risk of suicide, and the prevalence of suicide in a population. However, the PAF does not take into account the complexity of, and co-existing factors that can lead to suicide, but rather analyses risk factors as independent of each other. Despite this limitation, the PAF is still a valuable tool to better understand risk and inform prevention approaches.

The researchers of this paper who shared the results of previous research studies using the PAF to determine suicide risk factors have found:

• Psychiatric disorders are commonly identified as a large contributor to the risk of suicide and self-harm in high-income countries.
• Previous self-harm has also been identified as a significant contributor to self-harm in older adults in China and in repeat self-harm.
• Unemployment and low socioeconomic position have also been shown to increase suicide risk.

Researchers aimed to conduct an analysis in Australia using the PAF to identify populations disproportionately impacted by suicide in the Australian specific context.

What was done?

A classification system was used to identify population groups disproportionately impacted by suicide. This classification system was taken from a previous project the researchers had conducted, but the researchers included additional target populations of which are documented as being disproportionately impacted by suicide. The revised classification system included 17 population groups:

• Men
• Young people (aged 24 years or less)
• Adults (aged 25–64 years)
  
• Older adults (aged 65 years or more)
• People born overseas
• Aboriginal and Torres Strait Islander people
• People residing in rural or remote Australia [i.e., living outside of a major city according to Australian Statistical Geography Standard
• People with a mental health or behavioural condition
• People with a chronic physical health condition
• People who have previously attempted suicide
• Current or ex-serving military personnel
• Offender populations
• Lesbian, gay, or bisexual (LGB) populations (researchers were unable to include transgender people due to insufficient population-based data)
• People bereaved by suicide
• People from lower socioeconomic backgrounds
• People employed in manual trade or 'blue-collar' occupations
• Unemployed people.

To calculate the PAF for a target population, researchers first established a risk estimate by reviewing previous studies on the risk of death by suicide for each target population. For population groups that did not have sufficient risk data in the literature, the researchers used additional data from the Australian Bureau of Statistics (ABS) Causes of Death data, and Australian 2016 Census data.

To determine the PAF estimates for each population, the researchers:

1. Conducted a meta-analysis with Stata software
2. Calculated 95% confidence intervals using Monte-Carlo simulation models using Ersatz Software
3. Conducted re-calculations of the PAF on randomly drawn values defined for relative risk and proportion estimates.

What was found?

Large PAF values were associated with

• Men
• People bereaved by suicide
• People with a mental health or behavioural condition
• People with a chronic physical condition
• Adults aged 25–64 years
• LGB populations
• People employed in blue collar occupations.

PAF estimates of significance were estimated for:

• People with a previous suicide attempt
• Aboriginal and Torres Strait Islander populations.

Why are findings important?

The research identifies groups disproportionately impacted by suicide, and that those groups may benefit from targeted interventions. Overall suicide rates in Australia may be reduced if risk factors in identified population groups are addressed.

The researchers note that methodological limitations should be considered when interpreting the results, with relative risk estimates identified in population-based studies, not systematic reviews of individuals studies for each target population.