Association of Recreational Marijuana Use with Aneurysmal Subarachnoid Hemorrhage.

Objective: Our objective was to evaluate the effect of cannabis use on hospitalizations for aneurysmal subarachnoid hemorrhage (aSAH).

Methods: The Nationwide Inpatient Sample (2004-2011) was used to identify all patients (age 15-54) with a primary diagnosis of aSAH (International Classification of Diseases, Ninth Edition, Clinical Modification 430). We identified patients testing positive for cannabis use using all available diagnosis fields. The incidence and characteristics of aSAH hospitalizations among cannabis users were examined. Bivariate and multivariate analyses were performed to determine the effect of cannabis use on aSAH and in-hospital outcomes.

Results: Prior to adjustment, the incidence of aSAH in the cannabis cohort was slightly increased relative to the noncannabis cohort (relative risk: 1.07, 95% confidence interval [CI]: 1.02-1.11). Cannabis use in aSAH was more frequent among younger patients (40.44 ± 10.17 versus 43.74 ± 8.68, P < .0001), males (53.3% versus 40.76%, P < .0001), black patients (35.92% versus 19.10%, P < .0001), and Medicaid enrollees (31.13% versus 18.31%, P < .0001). The cannabis use cohort had greater overall illicit drug use but fewer medical risk factors for aSAH. Cannabis use (odds ratio: 1.18, 95% CI: 1.12-1.24) was found to be an independent predictor of aSAH when adjusting for demographics, substance use, and risk factors. Cannabis use was not associated with symptomatic cerebral vasospasm, inpatient mortality, or adverse discharge disposition.

Conclusions: Our analysis suggests that recreational marijuana use is independently associated with an 18% increased likelihood of aSAH. Further case-control studies may analyze inpatient outcomes and other understudied mechanisms behind cannabis-associated stroke.