Medical cannabis authorization and the risk of cardiovascular events : a longitudinal cohort study
Arsene Zongo, Cerina Lee, Jason R. B. Dyck, Jihane El‑Mourad, Elaine Hyshka, John G. Hanlon and Dean T. Eurich
BMC Cardiovascular Disorders, 2021, 21, 426
doi : 10.1186/s12872-021-02229-6
Background : Cannabis is increasingly used for therapeutic purpose. However, its safety profile is not well known. This study assessed the risk of cardiovascular-related emergency department (ED) visit and hospitalization in adult patients authorized to use medical cannabis in Ontario, Canada from 2014 to 2017.
Methods : This is a longitudinal cohort study of patients who received medical cannabis authorization and followedup in cannabis clinics, matched to population-based controls. The primary outcome was an ED visit or hospitalization for acute coronary syndrome (ACS) or stroke; and secondary outcome was for any cardiovascular event. Conditional Cox proportional hazards regression was used to assess the association between cannabis authorization and risk.
Results : 18,653 cannabis patients were matched to 51,243 controls. During a median follow-up of 242 days, the incidence rates for ACS or stroke were 7.19/1000 person-years and 5.67/1000 person-years in the cannabis and controls group, respectively- adjusted hazard ratio (aHR) of 1.44 (95% CI 1.08–1.93). When stratified by sex, the association was only statistically significant among males: aHR 1.77 (1.23–2.56). For the secondary outcome (any CV events), the aHR was 1.47 (1.26–1.72). The aHR among males and females were 1.52 (1.24–1.86) and 1.41 (1.11–1.79), respectively. Tested interaction between cannabis authorization and sex was not significant (p > 0.05).
Conclusions : Medical cannabis authorization was associated with an increased risk of ED visits or hospitalization for CV events including stroke and ACS.
Keywords : Longitudinal cohort study, Medical cannabis, Cardiovascular events, Acute coronary syndrome, Stroke, Hospitalization, Emergency department visit
• Among the safety concerns of medical cannabis use, there is limited data on the possible increased risk of cardiovascular events associated with the use of cannabis.
• This study is one of the few large epidemiological cohort studies that assesses the risk of cardiovascular CV events associated with the use of medical cannabis among patients in Ontario, Canada – 2014–2017.
• Overall, our results suggest that medical cannabis authorization was associated with a short-term increased risk of emergency department visit and hospitalization for cardiovascular events.
The number of individuals using cannabis to manage a health condition is increasing despite the lack of conclusive evidence on the efficacy and safety of cannabis for many of the indications for which it is used [1, 2]. In the first half of 2019, approximately 2.7 million Canadians were using cannabis for medical purposes . Cannabis is also the most commonly consumed licit/illicit substance in the world (recreational use) [4, 5]. Because the safety profile of cannabis remains unclear , the increasing use of cannabis could have unintended negative consequences for the users, the healthcare systems and public health in general.
Among the safety concerns, the possible increased risk of cardiovascular (CV) events associated with the use of cannabis is of concern . Different mechanisms have been suggested as possible causes of cannabis-related CV risk including a reversible cerebral vasoconstriction triggered by cannabis use (a possible mechanism of stroke) , increase in procoagulant proteins [7–9], ischemia by modulating cannabinoid receptors on vascular smooth muscles and human cardiomyocytes [10, 11] arrhythmia, and others . In a systematic review of 116 case reports, 29 observational studies, the authors concluded that while the data are limited (20 of the 29 studies were cross-sectional or case series), there is some suggestion that cannabis use may have negative CV consequences . Of note, the 116 individuals cases were young (mean age was 31 years), and mainly males (81.9%) and they mainly suffered from ischemic strokes or myocardial infarctions . Moreover, most of the studies included non-medical cannabis users. In other studies, however, an association between cannabis use and the risk of CV event was not found [13, 14]. Overall, the current state of evidence is limited to conclude on the CV safety of cannabis. Therefore, this study aimed to assess the risk of CV events associated with the use of cannabis among patients who received medical cannabis authorization in Ontario, Canada. We hypothesized that the medical use of cannabis will be associated with an increased risk of CV events compared to non-use.