The method that people use to attempt suicide has a large influence on the risk of later completed suicide, according to a new study published in the British Medical Journal today.
A Swedish study found that suicide attempts involving hanging or strangulation, drowning, firearm, jumping from a height, or gassing are moderately to strongly associated with an increased risk of suicide compared with poisoning or cutting.
Suicide is a leading cause of death and the risk of suicide following a suicide attempt is around 10% over follow-up of five to 35 years. However, there has been little research so far into the characteristics of a suicide attempt - such as being well planned, drastic or violent - and whether those have a bearing on the risk of a later completed suicide.
Researchers from the Karolinska Institute in Stockholm used national registers to carry out a study of 48,649 people admitted to hospital in Sweden due to a suicide attempt between 1973 and 1982.
They studied how the method of the suicide attempt might predict a completed suicide during a follow-up of 21-31 years, to the end of 2003.
The results showed that during follow up, 5,740 people (12%) went on to commit suicide and that suicide risk varied substantially by the method used at the previous suicide attempt.
Attempted suicide by poisoning was the most common method (84% of attempters) and was therefore linked to the majority of later suicides (4,270). However, the researchers found that the highest risk for eventual suicide (54% in men and 57% in women) was found for attempted suicide by hanging, strangulation, or suffocation.
People were around six times more likely to successfully commit suicide if they had attempted suicide by these methods previously, after adjusting for age, gender, education, immigrant status, and psychiatric illness.
More than 85% of these suicide cases died within one year following the prior suicide attempt.
For other methods such as gassing, jumping from a height, using a firearm or explosive, and drowning; the risks were significantly lower than for hanging, but were still higher at 1.8 times to 4 times more likely to successfully commit suicide.
People whose suicide attempt involved poisoning or cutting led to 12.3% or 13% respectively of later suicides.
The authors conclude: "The method used at a suicide attempt predicts later completed suicide also when controlling for sociodemographic confounding and co-occurring psychiatric disorder. Intensified aftercare is warranted after suicide attempts involving hanging, drowning, firearms or explosives, jumping from a height, or gassing."
In an accompanying editorial, Keith Hawton, Professor of Psychiatry at Warneford Hospital in Oxford, says that the results of this study have important implications for assessment and aftercare of patients who self harm. However, he warns that, "although use of more lethal methods of self harm is an important index of suicide risk, it should not obscure the fact that self harm in general is a key indicator of an increased risk of suicide."