Characterizing trends and patterns in benzodiazepine-related toxicity deaths in Ontario: a descriptive cross-sectional study

Objectives — The unregulated drug supply in Canada increasingly contains benzodiazepines, particularly those not approved for medical use, raising concerns about toxicity risk, especially when combined with opioids. Therefore, we aimed to describe trends in benzodiazepine-related toxicity deaths and compare their characteristics and circumstances by benzodiazepine type.

Methods — We conducted a descriptive cross-sectional study of accidental benzodiazepine-related toxicity deaths in Ontario between January 1, 2018 and June 30, 2022, using linked administrative healthcare at ICES including coroner’s investigation records from the Drug and Drug/Alcohol Related Death Database. We measured monthly crude rates of benzodiazepine toxicity deaths and summarized characteristics (age, sex, region of residence, etc.) and circumstances (number and types of substances involved, healthcare encounters for toxicities and substance use disorders, etc.) of decedents and compared these by benzodiazepine type (approved vs. not approved for medical use in Canada).

Results — Between January 2018 and June 2022, 782 Ontarians died of benzodiazepine-related toxicity (median age of 40 years), of which 70.5% were male and 88.6% resided in Southern Ontario The rate of benzodiazepine toxicity death peaked in December 2020 (0.27 per 100,000; N = 40). Overall, 98.1% of benzodiazepine deaths involved another substance, most commonly opioids (91.2%). Moreover, one-fifth (22.6%) of decedents had experienced a hospital-treated substance toxicity in the year prior to death, and almost two-thirds (64.1%) had a healthcare encounter with a substance use disorder diagnosis in the prior five years.

Conclusion — Benzodiazepines remain an important contributor to substance-related mortality in Ontario, with nearly 800 benzodiazepine-related toxicity deaths observed over a four-and-a-half-year period. As almost all deaths involved multiple substances, most commonly opioids, harm reduction and treatment programs must adapt to the evolving needs of people who use drugs who may experience both intentional and unintentional benzodiazepine exposure.