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People who survive a first attempt at suicide by poisoning are 42 times more likely than the general population to kill themselves by poisoning eventually, say the authors of the world's largest suicide-risk study.

“The durable risk of suicide long after the first self-poisoning episode suggests that to save lives we may need ongoing sustained initiatives," said Associate Professor Yaron Finkelstein, lead author of the study. “Most individuals who eventually died by suicide used more violent methods on subsequent attempts, and only seven per cent of them reached hospital alive.”

Researchers at the University of Toronto, The Hospital for Sick Children (SickKids), the Institute for Clinical Evaluative Sciences (ICES) and Sunnybrook Health Sciences Centre, based the study on more than 65,000 people who survived a self-poisoning episode – including adults and children. The results were published in the .

Researchers tracked every person who presented to an emergency department in Ontario for self-poisoning between April 2002 and December 2010. They found that the risk of death from accidents was 10 times higher following self-poisoning. 

This suggests that the first episode of deliberate self-poisoning is a strong predictor for subsequent suicide and premature death. 

”The hope is that our findings can be used to target this high-risk group and that it may influence suicide-prevention strategies to include long-term follow-up and efforts,” said Dr. Finkelstein, an associate professor of paediatrics, pharmacology and toxicology at U of T and staff physician in paediatric emergency medicine, and clinical pharmacology and toxicology, and associate scientist at SickKids. 

In Canada, suicide is the second leading cause of death in individuals aged 15 to 35 years, yet prevention efforts have remained a challenge, because the long-term outcomes following suicide attempts have not been well characterized. The present study also identified population-level suicide risk factors, which include being male, having engaged in multiple self-poisonings, higher socioeconomic status, a diagnosis of depression and psychiatric care in the year preceding the first self-poisoning episode. 

“Previous research has largely focused on short-term studies of patients with known psychiatric conditions in individual health-care centres,” said Finkelstein. “However, no one has looked at the entire population including both patients with diagnosed mental health conditions as well as everyone else in the community.

“Additionally, this is the first study to focus exclusively on individuals with a first presentation for self-poisoning. More research is required, and our multidisciplinary team is working hard to dig deeper, and is focusing on the vulnerable group of teenagers, as well as subsequent self-harm behaviours.” 

Dr. David Juurlink, the study's senior author, is professor of medicine, pediatrics, and health policy, management, and evaluation at U of T, senior scientist at ICES, and head of the division of clinical pharmacology and toxicology at Sunnybrook Health Sciences Centre. 

“It’s surprising how little we know about long-term outcomes after a first self-poisoning episode.” said Juurlink. “By following a very large group of patients over a long period of time, this study demonstrates that the risk of suicide remains elevated long after a first attempt. The implication of this is that suicide prevention efforts in these patients must also be sustained.”