Carotid Stiffness Is Associated With Incident Stroke: A Systematic Review and Individual Participant Data Meta-Analysis

BackgroundCarotid stiffening is considered a key element in the pathogenesis of stroke. However, results of studies evaluating the association between carotid stiffness and incident stroke have been inconsistent.ObjectivesThis study investigated whether carotid stiffness (as determined by ultrasonography) is associated with incident stroke and whether this association is independent of aortic stiffness as estimated by carotid-femoral pulse wave velocity (cfPWV). Additionally, we evaluated the incremental value of carotid stiffness for stroke risk prediction beyond Framingham risk factors and cfPWV.MethodsThis study included a systematic review and meta-analyses of aggregate and individual participant data (IPD), the latter of which was obtained by requesting individual-level data of all cohort studies with available data on carotid stiffness and cfPWV.ResultsTen studies (n = 22,472) were included in the aggregate data meta-analysis and 4 (n = 4,540) in the IPD meta-analysis. After adjusting for cardiovascular (CV) factors, the aggregate data meta-analysis showed that greater carotid stiffness (per SD) was associated with stroke (hazard ratio: 1.18; 95% confidence interval: 1.05 to 1.33). In addition, carotid stiffness was associated with total CV events and CV and all-cause mortality, but not with coronary heart disease events. In the IPD meta-analysis, additional adjustment for cfPWV did not materially change these associations. Carotid stiffness did improve stroke risk prediction beyond Framingham and cfPWV (integrative discrimination improvement: 0.4 percentage point [95% confidence interval: 0.1 to 0.6 percentage point] and continuous net reclassification improvement: 18.6% [95% confidence interval: 5.8% to 31.3%]).ConclusionsCarotid stiffness is associated with incident stroke independently of CV factors and aortic stiffness. In addition, carotid stiffness improves stroke risk prediction beyond Framingham and aortic stiffness.