Context Observational studies suggest that heavy alcohol consumption may increase
the risk of stroke while moderate consumption may decrease the risk.
Objective To examine the association between alcohol consumption and relative
risk of stroke.
Data Sources Studies published in English-language journals were retrieved by searching
MEDLINE (1966–April 2002) using Medical Subject Headings alcohol drinking, ethanol, cerebrovascular accident, cerebrovascular disorders, and intracranial embolism and thrombosis and the key word stroke; Dissertation Abstracts Online using the keywords stroke and alcohol; and bibliographies of
Study Selection From 122 relevant retrieved reports, 35 observational studies (cohort
or case control) in which total stroke, ischemic stroke, or hemorrhagic (intracerebral
or total) stroke was an end point; the relative risk or relative odds and
their variance (or data to calculate them) of stroke associated with alcohol
consumption were reported; alcohol consumption was quantified; and abstainers
served as the reference group.
Data Extraction Information on study design, participant characteristics, level of alcohol
consumption, stroke outcome, control for potential confounding factors, and
risk estimates was abstracted independently by 3 investigators using a standardized
Data Synthesis A random-effects model and meta-regression analysis were used to pool
data from individual studies. Compared with abstainers, consumption of more
than 60 g of alcohol per day was associated with an increased relative risk
of total stroke, 1.64 (95% confidence interval [CI], 1.39-1.93); ischemic
stroke, 1.69 (95% CI, 1.34-2.15); and hemorrhagic stroke, 2.18 (95% CI, 1.48-3.20),
while consumption of less than 12 g/d was associated with a reduced relative
risk of total stroke, 0.83 (95%, CI, 0.75-0.91) and ischemic stroke, 0.80
(95% CI, 0.67-0.96), and consumption of 12 to 24 g/d was associated with a
reduced relative risk of ischemic stroke, 0.72 (95%, CI, 0.57-0.91). The meta-regression
analysis revealed a significant nonlinear relationship between alcohol consumption
and total and ischemic stroke and a linear relationship between alcohol consumption
and hemorrhagic stroke.
Conclusions These results indicate that heavy alcohol consumption increases the
relative risk of stroke while light or moderate alcohol consumption may be
protective against total and ischemic stroke.