Determining intent behind poisoning suicides

We thank Liu and colleagues for their article that described important temporal patterns about suicide in Canada.1 The decline observed in the age-standardized rate of suicide by poisoning leads us to wonder whether this may be because of misclassification of such suicides. This is important given concerns about rising suicidality among young and middle-aged adults, particularly during the current COVID-19 pandemic.2

Accidental poisonings now mainly include illicit drug overdoses among adults, and it is at the discretion of a medical examiner or coroner to determine whether or not that death was “accidental,” based on the circumstances and evidence surrounding the death.3 Deaths by firearm or suffocation (hanging) are much more likely to be deemed a suicide in the absence of any corroborating evidence (e.g., a suicide note) or an external perpetrator (i.e., evidence of a homicide). In contrast, a death by an overdose is particularly susceptible to being misclassified as an accidental poisoning, especially in the current era of opioid overuse.

Recent Canadian data have shown a resurgence in poisoning deaths because of the opioid epidemic. More than 50% of poisonings among Canadian youth presenting to hospital are intentional.4 Population-based data show that accidental poisonings and overdoses account for nearly half of all injury-related deaths among those aged 15–24 years, with greater than half of all deaths among those aged 18–24 years occurring outside of hospital.5 Hence, it is quite conceivable that more poisonings in Canada are both intentional and suicidal than realized.

Future research should re-evaluate poisoning deaths of undetermined intent, to elucidate what proportion are actually missed suicides.