Method of Suicide Attempt Influences Risk for Later Successful Suicide

From Medscape Medical News

Megan Brooks

August 3, 2010 — The method used in an initial suicide attempt influences the risk for a later successful suicide, with those who attempt suicide by hanging, drowning, shooting by firearm, jumping, or gassing most likely to succeed on subsequent attempts, new research suggests.

"Intensified aftercare is warranted for suicide attempts" involving these methods, the researchers conclude in a report published online July 13 in the British Medical Journal.

The study also shows that people who attempt suicide by these highly lethal methods are likely to choose the same method on subsequent attempts.

Using Swedish national registry data, Bo Runeson, MD, PhD, and colleagues from the Karolinska Institute in Stockholm, Sweden, studied 48,649 individuals admitted to the hospital between 1973 and 1982 after attempted suicide. They compared risks for subsequent suicide attempt by index suicide method during a 21- to 31-year follow-up period, ending in 2003.

During follow-up, a total of 5740 subjects (11.8%) successfully committed suicide and the risk for suicide varied considerably by the method used on the index suicide attempt.

Attempted suicide by poisoning was the most common method, used by 83.8% of attempters, and was linked to most later successful suicides (n = 4270).

However, the highest relative risk for eventual successful suicide was found for those in whom the index attempt was by hanging, strangulation, or suffocation. In this group, 258 men (53.9%) and 125 women (56.6%) later successfully committed suicide (hazard ratio, 6.2; 95% confidence interval, 5.5 – 6.9; after adjustment for age, sex, education, immigrant status, and co-occurring psychiatric morbidity), and 333 of these individuals (87%) did so within 1 year of the index attempt.

First Year Most Risky

"As in previous studies, successful suicide was particularly common during the first year after the index attempt," the study authors note, perhaps stemming from a distressing life situation or "intense symptom rich phases of coexisting psychiatric disorder." For example, when stratified by psychiatric comorbidity, 69% of subjects who attempted suicide by hanging and had a psychotic disorder died from suicide within 1 year.

"The important short term excess in suicide rate after a suicide attempt by such means has not been acknowledged in previous studies," they note, "and suggests possible benefits of more focused aftercare during the first few years after admission to hospital."

For other methods — gassing, firearm/explosive, jumping, and drowning — relative risks were significantly lower than for hanging but still increased at 1.8, 3.2, 3.2, and 4.0, respectively. Cutting, and “other” methods conferred risks at levels similar to that of poisoning (the reference category).

Most of those who successfully committed suicide used the same method as they did at the index attempt, the study authors report. For example, 93% of men and 92% of women who used hanging in the index attempt later died from suicide by hanging; 82% of men and 86% of women who used drowning in the index attempt died by drowning later.

The researchers note that aftercare for suicide attempters is often based on estimates of suicidal intent. Other reports suggest that psychiatric disorders should be considered. The new data, the study authors say, “strongly indicate that such assessments should also be guided by the method used.”

Keith Hawton, MD, of the Centre for Suicide Research, University Department of Psychiatry, Warneford Hospital, in Oxford, England, agrees. However, he warns in an accompanying editorial 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."

Dr. Runeson and colleagues and Dr. Hawton have disclosed no relevant financial relationships.

BMJ. 2010;340:c3222. Published online July 13, 2010.