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Risk of suicide following deliberate self-poisoning


Importance — Suicide is the 10th leading cause of death in the United States and its rate has risen by 16% in the past decade. Deliberate self-poisoning is the leading method of attempted suicide. Unlike more violent methods, which are almost universally fatal, survival following self-poisoning is common, providing an opportunity for secondary prevention. However, the long-term risk of suicide following a first episode of self-poisoning is unknown.

Objective — To determine the risk of suicide and mortality from other causes following a first self-poisoning episode.

Design — Population-based cohort study using multiple linked healthcare databases.

Setting — Ontario, Canada from April 2002 to March 2011.

Participants — The researchers identified all individuals with a first self-poisoning episode. For each individual with a deliberate self-poisoning, the researchers randomly selected one control from the same population with no such history, matched on age (within 3 months), sex and calendar year.

Main Outcomes — The primary analysis examined the risk of suicide following discharge after self-poisoning. Secondary analyses explored factors associated with suicide and examined the risk of death from accidents and death from any cause.

Results — The researchers identified 65,784 patients (including 18,482 [28.1%] younger than 20 years) discharged after a first self-poisoning episode. Over a median follow-up of 5.3 years, 4,176 died, including 976 (23.4%) deaths from suicide. The risk of suicide following self-poisoning was markedly increased relative to controls (adjusted hazard ratio 42.0; 95% confidence interval 27.8 to 63.4), corresponding to a suicide rate of 280 vs. 10 per 100,000 person-years, respectively. The median time from hospital discharge to suicide was 585 days (inter-quartile range 147 to 1,301). Older age, male sex, multiple intervening self-poisoning episodes, higher socioeconomic status, depression and recent psychiatric care were strongly associated with suicide. Patients with self-poisoning were also more likely to die from accidents (adjusted hazard ratio 10.5; 95% confidence interval 8.1 to 13.5) and all causes combined (adjusted hazard ratio 5.6; 95% confidence interval 5.1 to 6.0).

Conclusions and Relevance — A first self-poisoning episode is a strong predictor of subsequent suicide and premature death. Most suicides occur long after the index poisoning, emphasizing the importance of longitudinal, sustained secondary prevention initiatives.



Finkelstein Y, Macdonald EM, Hollands S, Sivilotti MLA, Hutson JR, Mamdani MM, Koren G, Juurlink DN; Canadian Drug Safety and Effectiveness Research Network (CDSERN). JAMA Psychiatry. 2015; 72(6):570-5. Epub 2015 Apr 1.

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