A Canadian study has found that a person's risk of suicide after an initial attempt was 42 times higher than that of the general population and could persist for years.
In what is said to be the largest study of its kind, Toronto researchers tracked every person who came to a hospital emergency department in Ontario as a result of self-poisoning between April, 2002, and December, 2010.
They identified 65,784 children and adults who survived the suicide attempt – including almost 18,500 teenagers.
Of the 65,000-plus patients discharged after self-poisoning – the most common way of trying to take one's own life – 4,176 individuals died during the followup study period, 976 of them by suicide.
Among those who killed themselves were 107 teens, who took their own lives just over two years on average after their first attempt.
The risk of death from apparent accidents was also 10 times higher after that first suicide attempt.
"I think the key message is that patients at all ages – both teenagers and adults – who present to hospital with a first episode of intentional self-poisoning are at a significantly increased risk of suicide over the ensuing decade," said Yaron Finkelstein, the lead author of the study that was published on Wednesday in the journal JAMA Psychiatry.
Self-poisoning is often the result of overdosing on over-the-counter or prescription drugs or ingesting a noxious substance.
While some are treated and discharged from the ER, more severe cases are admitted for critical care or for psychiatric care if they appear unstable and likely to harm themselves again imminently.
"About 99 per cent of those who reach hospital alive are surviving," said Dr. Finkelstein, an emergency room physician at the Hospital for Sick Children. "And that is the opportunity to identify them and implement prevention for subsequent attempts.
"Most individuals who eventually died by suicide used more violent methods on subsequent attempts, and only seven per cent of them reached hospital alive."
The median time from hospital discharge after a first attempt to a completed suicide was 18 months, the researchers found, and about one-quarter took their own lives more than four years later.
"The suicide risk is durable over many years after the first presentation," said Dr. Finkelstein.
"And therefore we suggest that prevention efforts should target these populations because of the high risk, and at the same time those initiatives should be sustained over time."
Factors that increase the risk of a renewed attempted at suicide are advancing age, being male, high socioeconomic status and a diagnosis of depression and psychiatric care in the year preceding the first attempt, he added.
The study also found that initial self-poisoning attempts were associated with an increased risk of accidental death over the following decade, often due to falls from heights or motor vehicle crashes, without a suicide note.
"We suspect that some accidental deaths or deaths of indeterminate intent are in fact suicides that were not classified as such by investigating coroners in the absence of definitive proof of intent," the authors write.
Jennifer Brasch, a psychiatrist in the Concurrent Disorders Clinic at St. Joseph's Healthcare in Hamilton, said the study's finding that an unsuccessful attempt continues to put a person at high risk for suicide "should be a flag to every doctor."
"People need a primary-care physician or psychiatrist or psychiatric clinic that provides ongoing followup," said Dr. Brasch, who was not involved in the study.
There are also interventions that have been shown to help prevent a subsequent suicide attempt, including hospital-based programs that teach patients how to combat suicidal thoughts and develop problem-solving skills, as well as offering peer support, she said.