In systematic review, we aimed to describe the prevalence, characteristics and outcome of ischemic strokes in patients with history of marijuana use.

As marijuana is increasingly viewed by the public as safe and harmless, there is a notable rise in the prevalence of marijuana use and associated complications. Marijuana contains the vasoactive substance tetrahydrocannabinol (THC), which has been shown to independently increase the risk of ischemic stroke. The prevalence and outcome of ischemic strokes due to marijuana use is poor reported.

Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, we searched PubMed and 8 other databases, through April 2019, for randomized clinical trials and observational studies reporting ischemic stroke as a complication of marijuana.

Of 3,164 records screened, 12 studies met the inclusion criteria. The studies were published between 2011 and 2018 (median 2015) and included 6 cohort (5 retrospective and 1 prospective), 3 cross-sectional, 2 case-series and 1 case-control studies. These encompassed 4,437,335 patients, of which 405,099 (9%) used marijuana. Among marijuana users, 251,297 (62%) were male and the median age was 41 years (range 23-47). Ischemic stroke developed in 12,130 patients (3% of marijuana users), of which 3,030 patients (25%) used other vasoactive substances. Among patients with ischemic stroke and marijuana use, the most commonly reported stroke risk factors were hypertension (22%), smoking (19%), hyperlipidemia (12%), heart failure (8%) and diabetes (7%). The median overall mortality of patients with ischemic stroke was 12.5 % (range 2.7-17). There was limited data on the neurological outcome and recovery after ischemic stroke in marijuana users.

Data describing the prevalence and outcome of ischemic stroke in marijuana users remain limited. Our findings highlight a dire need for further research that focus on the various effects of marijuana use on cerebrovascular complications and methods to mitigate negative outcomes.