Medical Cannabis Authorization and the Risk of Cardiovascular Events: A Longitudinal Cohort Study

Abstract Background Despite the rising rates of legalization of cannabis worldwide, very few investigators have studied the effects of medical cannabis use on healthcare utilization and subsequent cardiovascular (CV) risk. This study assesses the risk of CV-related emergency department (ED) visit/hospitalization in adult patients authorized to use medical cannabis in Ontario, Canada from 2014–2017. Methods This is a longitudinal cohort study of patients who received medical cannabis authorization and followed-up in cannabis clinics, matched to population-based controls. The primary outcome was an ED visit/hospitalization for any CV event; and secondary outcome was for acute coronary syndrome (ACS)/stroke. Conditional Cox proportional hazards regression was used to assess the association between cannabis use and risk. Results 18,653 cannabis patients were matched to 5,1243 controls. Incidence rates for any CV event were 28.34/1000 person-years and 19/1000 person-years in the cannabis and controls group, respectively- (aHR) of 1.52 (95%CI: 1.31–1.77). The aHR among patients with a history of CV event and those without were 1.50 (1.28–1.75) and 1.26 (1.03–1.55), respectively. The aHR among males and females were 1.52 (1.24–1.87) and 1.41 (1.11–1.80). For the ACS and stroke, the aHR was 1.44 (95%CI: 1.08–1.93). When stratified by sex, only men had an increased risk of ACS and stroke; aHR 1.77 (1.23–2.56). Conclusions Medical cannabis authorization was associated with an increased risk of ED visits or hospitalization for CV events including stroke and ACS - among males and for patients with a prior CV condition.