Coffee Consumption and Stroke Risk: Evidence from a Systematic Review and Meta-Analysis of more than 2.4 Million Men and Women

Abstract Background Results of stroke risk and coffee consumption are inconclusive. This study aimed to provide an updated systematic review and meta-analysis of the association between coffee consumption and stroke risk. Method Random-effects models were used to pool relative risk estimates (RRs) with 95% confidence intervals (CIs). The highest versus the lowest categories of coffee consumption as well as dose-response analysis with a one-stage robust error meta-regression model (REMR) were assessed for stroke risk. Results In total, 21 studies including 30 independent cohorts that comprised more than 2.4 million participants were included. The pooled RR with 95% CI for the highest versus the lowest categories of coffee consumption was 0.87 (0.80–0.94) with moderate heterogeneity (I2 = 32.0%). Sensitivity analysis suggested that the influence of each individual data set to an overall result was not significant. As suggested by Begg's funnel plots and Egger tests (p=0.006), some evidence for publication bias was observed. Further analysis with the trim-and-fill method indicated no noticeable harm to our results was generated by any potential bias. Dose-response analysis suggested a nonlinear relationship (U-shape) between stroke risk and coffee (p = 0.0002). The strongest association for stroke (21% lower risk) was found for coffee consumption of 3–4 cups/day and no further reduction in stroke risk was observed with increasing levels of coffee consumption beyond this amount. Conclusion Our study provided evidence of a significant inverse association between coffee consumption and risk of stroke. Future large prospective studies with excellent design are warranted to confirm our findings and provide a more definitive conclusion.