Alcohol intake and risk of stroke: A dose-response meta-analysis of prospective studies

Background Alcohol intake is inconsistently associated with the risk of stroke morbidity and mortality. The purpose of this study was to summarize the evidence regarding this relationship by using a dose-response meta-analytic approach. Methods We performed electronic searches of PubMed, EMBASE, and the Cochrane Library to identify relevant prospective studies. Only prospective studies that reported effect estimates with 95% confidence intervals (CIs) of stroke morbidity and mortality for more than 2 categories of alcohol intake were included. Results We included 27 prospective studies reporting data on 1,425,513 individuals. Low alcohol intake was associated with a reduced risk of total stroke (risk ratio [RR], 0.85; 95% CI: 0.75-0.95; P = 0.005), ischemic stroke (RR, 0.81; 95% CI: 0.74-0.90; P < 0.001), and stroke mortality (RR, 0.67; 95% CI: 0.53-0.85; P = 0.001), but it had no significant effect on hemorrhagic stroke. Moderate alcohol intake had little or no effect on the risks of total stroke, hemorrhagic stroke, ischemic stroke, and stroke mortality. Heavy alcohol intake was associated with an increased risk of total stroke (RR, 1.20; 95% CI: 1.01-1.43; P = 0.034), but it had no significant effect on hemorrhagic stroke, ischemic stroke, and stroke mortality. Conclusions Low alcohol intake is associated with a reduced risk of stroke morbidity and mortality, whereas heavy alcohol intake is associated with an increased risk of total stroke. The association between alcohol intake and stroke morbidity and mortality is J-shaped.