Substances and substance combinations among accidental substance-related acute toxicity deaths (AATDs) in Canada from...

Canada has seen a rise in substance-related accidental acute toxicity deaths (AATDs) in recent years. Research indicates that fentanyl opioids, non-fentanyl opioids, and stimulants are classes of concern and that multidrug AATDs have increased. However, there is limited information regarding the specific substances involved. This study aims to identify the substances and substance combinations as well as substance classes and substance class combinations most often involved in AATDs across Canada between 2016 and 2017. It also examines variations in substances by year and across sociodemographic, socioeconomic, and geographic factors.

Data were abstracted from the coroner and medical examiner files of all AATDs that occurred across Canada between 2016 and 2017. Top substances and classes detected in or contributing to AATDs were identified based on toxicology reports and cause of death statements. AATDs were stratified by year of death, age, sex, residence community type, neighbourhood income quintile, and province/region to understand variations in the substances contributing to AATDs. Combinations of substances and classes contributing to death were examined with UpSet plots and trends of select substances were visualized over time with ribbon charts. An algorithm was developed to report the source and origin of the substances based on prescription history and scene evidence.

Fentanyl, cocaine, alcohol, and methamphetamine were the top substances contributing to the 7,902 AATDs identified between 2016 and 2017 in Canada. While stimulants and opioids were the most common substance classes contributing to AATDs, other classes, including benzodiazepines and acetaminophen also emerged as classes among the top contributors. Between 2016 and 2017, the proportion of AATDs attributable to diacetylmorphine (heroin) per quarter decreased while the proportion of AATDs attributable to carfentanil per quarter increased. AATDs involving more than one substance occurred across all sociodemographic, socioeconomic, and geographic groups. Substances contributing to AATDs more commonly originated from non-pharmaceutical sources than from pharmaceutical sources.

Specific substances and substance combinations contributing to deaths vary over time and geographic areas. Opioids and stimulants are both detected in and contribute to a majority of AATDs, but the substance-related acute toxicity death crisis is complex and attributable to many substance classes. Understanding these differences will allow for targeted substance-related policies, prevention, and harm reduction efforts.