Background and purpose: Ischemic stroke is associated with the metabolic syndrome (MetS) as diagnosed using dichotomous criteria; however, these criteria exhibit racial/ethnic discrepancies. Our goal was to assess whether ischemic stroke risk extended over the spectrum of worsening MetS severity using a sex- and race/ethnicity-specific MetS-severity Z score.
Methods: We used Cox-proportional hazards models to assess the relationship between baseline MetS-Z score and incident ischemic stroke among participants of the Atherosclerosis Risk in Communities study and Jackson Heart Study who were free from diabetes, coronary heart disease or stroke at baseline, evaluating 13 141 white and black individuals with mean follow-up of 18.6 years.
Results: We found that risk of ischemic stroke increased consistently with MetS severity, with a hazard ratio of 1.75 (95% CI, 1.35-2.27) for those >75th percentile compared to those <25th percentile. This risk was highest for white females (hazard ratio, 2.63 [CI, 1.70-4.07]) though without significant interaction by sex and race. Relationships between stroke and all the individual components of MetS were only noted for white females, though again without sex-race interactions. Hazard ratio's for systolic blood pressure and stroke were significant among all sex/racial subgroups.
Conclusions: Ischemic stroke risk increased over the spectrum of MetS severity in the absence of baseline diabetes mellitus, further implicating potential etiologic risks from processes underlying MetS. Individuals with elevated MetS severity should be counselled toward lifestyle modification to lower ischemic stroke risk.
Keywords: blood pressure; fasting; glucose; metabolic syndrome; risk factors.