Suicide prediction tools leave some people vulnerable

Preventing suicide is the cornerstone of mental health treatment. But the way it is being done could be causing more harm than good.

That's the controversial message from a recent analysis, which suggests that the main factor doctors use to assess suicide risk ends up diverting treatment away from people who may need it while over-treating those who may not.

It is so hard to predict who will actually harm themselves that about 98 to 99 per cent of people deemed "high-risk" and incarcerated or heavily medicated never go on to commit suicide, says psychiatrist Matthew Large at the University of New South Wales in Sydney, Australia. Most suicides occur among those with psychiatric conditions deemed to be low-risk.

"Even the people we categorise as low-risk are many times more likely to kill themselves than members of the general community," Large says. "A low- and high-risk psychiatric patient is like looking at the difference between the 10th and 11th floor and not looking at the difference between those floors and the ground."

Large says the "key pillar" of risk-assessment is suicidal ideation ? having thoughts about suicide. This kind of ideation usually results in automatic high-risk categorisation.

But when Large looked through all the evidence with Olav Nielssen from the University of Sydney, Australia, he found that the link between suicide ideation and suicide is not necessarily as strong as often assumed.

Other factors

Other risk factors should also be considered, he says. A psychiatric patient with suicidal ideation may be 2.5 times as likely to commit suicide as one without ? but in some populations, men are about four times as likely to die from suicide as women.

Large says by relying on suicidal ideation to choose who to treat, risk-assessment might even result in more suicides overall since it means that fewer resources are targeted at the larger "low-risk" group.

Robert Goldney, a psychiatrist from the University of Adelaide, Australia, says Large might be right about the numbers, but risks "throwing the baby out with the bathwater".

"It just defies logic to say that there is no association between thinking about suicide and suicide," he says. "There has to be some sort of thought prior to suicide."

Large agrees it is counter-intuitive, but says there are patients who die from suicide without any forward planning. What's more, patients may not tell their doctor if they have suicidal ideas ? and those who do may never hurt themselves.

Brian Draper, a psychiatrist at the University of New South Wales, says determining risk is imperfect and difficult ? but he argues suicidal ideas help doctors understand changes in a patient's illness, and inform risk judgements.

Large says suicidal ideas should be investigated and treated, but just not used to judge risk.

"Mostly risk assessment is a kind of comforting myth ? the idea that we can get by with rationing limited resources on this basis," he says.

Journal reference: American Journal of Psychiatry, DOI: 10.1176/appi.ajp.2012.11111674

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