Methods of non-fatal self-harm may help to predict future risk of suicide

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NICE guidance recommends that all people who self-harm and are admitted to hospital are given mental health and risk assessment:

Everyone who has self-harmed should have a comprehensive assessment of needs and risk; engaging the service user is a prerequisite.
- Taken from NICE Self-harm guidance (CG16), Nov 2004

This new prospective cohort study conducted by a research team from Oxford University’s Centre for Suicide Research, set out to investigate weather the most recent method of non-fatal self-harm could be used to predict the risk of future suicide.

The researchers took data from the Multicentre Study of Self-harm conducted in 3 centres in England from 2000-2010. Over 30,000 people presented to emergency departments in 6 hospitals from 2000-2007 with non-fatal self-harm. 41.3% of this cohort were male and the median age was 27 years old.

The outcome of interest was suicide and this was measured over a 3-11 year follow-up period.

Here’s what they found:

  • 378 individuals (1.25% of the total cohort) killed themselves during the study
  • 76.2% of participants had one episode of self-harm during the study, 13.3% had two episodes, 10.7% had three or more episodes
  • When compared with self-poisoning, all other methods of self-harm at the last episode were associated with a significantly increased risk of suicide as a whole:
    • Cutting (HR 1.79, 95% CI 1.62 to 1.98)
    • Hanging/asphyxiation (HR 2.65, 95% CI 2.36 to 2.97)
    • Carbon monoxide (CO)/other gas (HR 5.02, 95% CI 2.33 to 10.86)
    • Traffic related (HR 4.41, 95% CI 2.93 to 6.63)
    • All other self-injuries (HR 1.88, 95% CI 1.01 to 3.50)
  • When compared with self-poisoning, most other methods of self-injury at the last episode were associated with a significantly increased risk of suicide by self-injury (defined as all methods other than poisoning):
    • Cutting (HR 2.29, 95% CI 1.67 to 3.13)
    • Hanging/asphyxiation (HR 4.15, 95% CI 3.11 to 5.54)
    • CO/other gas (HR 6.70, 95% CI 1.70 to 26.49)
    • Traffic related (HR 5.65, 95% CI 2.40 to 13.32)
  • Other methods of self-injury were not significantly associated with risk of suicide by self-injury (HR 2.55, 95% CI 0.93 to 6.99)
  • People presenting with all methods of self-harm had similar risks of subsequent suicide by self-poisoning
  • 32% of people who killed themselves used the same method for their death as for their last episode of self-harm

It is important to stress that this study focused specifically on people who were admitted to an emergency department for self-harm and so does not include others who never reach hospital.

The authors concluded:

Method of self-harm may aid identification of individuals at high risk of suicide. Individuals using more dangerous methods (e.g. hanging, CO/other gas) should receive intensive follow-up. Method changes in repeated self-harm were not associated with suicide. Our findings reinforce national guidance that all patients presenting with self-harm, regardless of method, should receive a psychosocial assessment.

Links

Bergen H, Hawton K, Waters K, Ness J, Cooper J, Steeg S, Kapur N. How do methods of non-fatal self-harm relate to eventual suicide? J Affect Disord. 2012 Feb;136(3):526-33. Epub 2011 Nov 29. [PubMed abstract]

Self-harm: The short-term physical and psychological management and secondary prevention of self-harm in primary and secondary care (PDF). NICE CG16, Nov 2004.

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André Tomlin

André Tomlin
André started the Mental Elf website in May 2011. He has worked as an Information Scientist in Mental Health since the late nineties; initially at Oxford University's Centre for Evidence-Based Mental Health and since 2002 as the Managing Director of Minervation Ltd. He loves blogging, social media and elves! He also has established interests in evidence-based healthcare, usability testing and web design.

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