Statin Adherence and the Risk of Stroke: A Dose-Response Meta-Analysis

Background Statins are one of the most common medications for stroke prevention. Increasing evidence indicates that the effect of statins against stroke may depend on the optimal adherence of the patients to the long-term therapies. However, the magnitude of the association between statin adherence and the risk of stroke has not been determined. Objective We conducted a dose-response meta-analysis to investigate the association between statin adherence and the risk of stroke. Methods The Medline and Embase databases were systematically searched to identify relevant observational studies that evaluated the association between statin adherence and stroke risk. Statin adherence was primarily quantified by the proportion of days covered by prescribed statins. Studies in which relative risks (RRs) with 95% confidence intervals (CIs) for the association between statin adherence and stroke risk were reported or could be estimated were included in this meta-analysis. Results A total of 15 studies with 710,504 participants were included. The pooled RR of total stroke for the categories with the highest compared with the lowest adherence to statins was 0.72 (95% CI 0.65-0.79). Stratified by stroke subtype, the pooled RR for ischemic stroke (IS) was 0.83 (95% CI 0.74-0.92) and for hemorrhagic stroke was 0.75 (95% CI 0.51-1.09). The dose-response analysis indicated that an improvement in statin adherence of 20% was associated with an 8% lower risk of total stroke (RR 0.92; 95% CI 0.89-0.94). In the subgroup analysis for IS, an improvement in statin adherence of 20% was associated with a 7% lower risk of IS (RR 0.93; 95% CI 0.88-0.99). Conclusion Improved adherence to statins was associated with a lower risk of stroke, particularly of IS.