Marijuana Legalization and Opioid Use Disorder in Ontario, Canada, From 2015 to 2021

This study examined the trends in opioid-related hospitalizations and deaths in Ontario, Canada, from 2015, to 2021, with a particular focus on the periods before and after cannabis legalization. The social problem addressed was the ongoing opioid crisis, exacerbated by rising opioid-related health issues. Grounded in the harm reduction theory, this research explored whether cannabis legalization could serve as a substitute to mitigate opioid use disorder. Data were extracted from the Discharge Database, Emergency Department Database, National Ambulatory Care Reporting System, and Hospital Morbidity Database. Analysis using the generalized estimation equation (GEE) method revealed a significant increase in opioid-related hospitalizations, which rose from a mean of 405.56 (SD = 38.67) in 2015 to 1486.33 (SD = 49.803) in 2021, representing 366% increase. The hospitalization rate notably increased twofold in 2020 and threefold in 2021 compared to 2015. A one-way ANOVA demonstrated a statistically significant effect of time on both hospitalizations, F(6,65) = 37.67, p < 0.001, and deaths, F(6,65) = 8.67, p < 0.001. The GEE analysis indicated a significant rise in monthly hospitalizations from the illegal to the legal cannabis period (B = 61.99, SE = 6.37, p < 0.001), along with significant yearly increases in opioid-related deaths from 2015 to 2021. These findings suggest that opioid-related health issues intensified during the cannabis legalization era, though the specific impact of the COVID-19 pandemic on these trends remains unclear. The study’s implications for social change include insights into the potential role of cannabis legalization as a harm reduction strategy, which could inform policies aimed at addressing the opioid crisis.