Heavy cannabis users at elevated risk of stroke: evidence from a general population survey.

OBJECTIVE

Case reports and hospital-based case-control studies suggest that cannabis use may increase the risk of stroke. We examined the risk of non-fatal stroke or transient ischemic attack (TIA) among cannabis users in the general community.

METHODS

A general population survey of Australians aged 20-24 years (n=2,383), 40-44 years (n=2,525) and 60-64 years (n=2,547) was used to determine the odds of lifetime stroke or TIA among participants who had smoked cannabis in the past year while adjusting for other stroke risk factors.

RESULTS

There were 153 stroke/TIA cases (2.1%). After adjusting for age cohort, past year cannabis users (n=1,043) had 3.3 times the rate of stroke/TIA (95% CI 1.8-6.3, p<0.001). The incidence rate ratio (IRR) reduced to 2.3 after adjustment for covariates related to stroke, including tobacco smoking (95% CI 1.1-4.5). Elevated stroke/TIA was specific to participants who used cannabis weekly or more often (IRR 4.7, 95% CI 2.1-10.7) with no elevation among participants who used cannabis less often.

CONCLUSIONS

Heavy cannabis users in the general community have a higher rate of non-fatal stroke or transient ischemic attack than non-cannabis users.