Grant: Project Grant

Opioid overdoses, polysubstance misuse, mental health disorders, and trauma place a significant health and economic burden on Canadians. While recreational cannabis legalization (RCL) has been used in some U.S.A states to control the opioid epidemic and for potential positive health benefits, two Canadian studies have already reported an increase in rates of emergency department (ED) visits for cannabis poisoning since RCL. Compared to other ED patients, those with cannabis poisoning have a higher frequency of mental health diagnoses, specifically mood and anxiety disorders. Most patients in the ED with cannabis poisoning have also used at least one other substance, primarily alcohol. Acute cannabis use is known to change perceptions and behaviour, and has been found to increase the risk of injury, including traffic deaths and falls, which is the most common cause of traumatic brain injury (TBI) in older adults. Although some regions in the U.S.A have found that rates of traffic deaths and cannabis poisonings increased after RCL, in Canada and elsewhere there is a lack of strong evidence on RCL's impact on other health outcomes and their associated costs. In this study, we will assess whether monthly rates of hospitalizations, ED visits, and deaths for substance use (including cannabis, alcohol, and/or opioids), mental health outcomes, and injuries (including TBI) have changed overall and among different groups/locations since RCL in Canada. We will also determine the effect of RCL on healthcare service utilization costs for all health outcomes. This research is important for guiding policy, education, and prevention strategies that support and improve the health and well-being of all Canadians.