The impact of recreational cannabis legalization on cannabis-related acute care events among adults with schizophrenia.

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Patients with schizophrenia have a higher risk of cannabis use disorder and may be uniquely affected by the legalization of recreational cannabis. This study examined whether cannabis legalization led to changes in acute care utilization among patients with schizophrenia. Using linked health administrative data, we included adult patients with schizophrenia in Ontario from October 2015 to May 2021 (n = 121,061). We examined the differences in cannabis, psychosis, and mental health-related emergency department (ED) visits over three periods: pre-legalization, legalization of flowers and herbs (phase 1), and legalization of edibles, extracts, and topicals (phase 2) using interrupted time-series methods. Our study found that phase 1 was associated with decreases in cannabis-related, mental health-related, and cannabis + psychosis-related ED visits among the patients with schizophrenia. Notably, an immediate 25.8% (95% CI 13.8-37.6%) decrease in cannabis-related ED visits was observed in men, and an immediate 18.5% decrease in mental health-related ED visits (95% CI 6.0-31.2%) in women. These decreases were also shown in the comparative ITS models, demonstrating that the changes observed were distinct from trends in the general population. However, phase 2 was not associated with any significant changes. Despite higher baseline rates of acute care utilization among patients with schizophrenia, cannabis legalization was associated with significant reductions, particularly during phase 1. Our findings suggest that regulatory measures accompanying legalization could enhance the quality and safety of cannabis products, potentially leading to fewer adverse health outcomes in vulnerable patient populations. Further research is needed to optimize healthcare responses for this vulnerable population.