Background and ObjectivesStroke in young adults constitutes 15%–18% of all ischemic stroke cases. Black individuals have an excess risk of ischemic stroke especially in young adults. Although it is known that Black patients have a higher prevalence of hypertension and diabetes, few studies have addressed the association of concurrent multiple vascular risk factors with the excess risk of early-onset stroke among Black individuals.MethodsA population-based case-control study of early-onset ischemic stroke, ages 15–49 years, was conducted in the Baltimore-Washington DC region between 1992 and 2007. Presence of the risk factors of obesity, hypertension, diabetes, and current smoking were obtained from both cases and controls by an in-person interview. Risk factor groups were defined as (1) 1 risk factor, (2) 2 risk factors, (3) 3 risk factors, and (4) 4 risk factors. Logistic regression analysis adjusting for age and sex was used to evaluate the association between each risk factor group and ischemic stroke compared with the reference group with no risk factors.ResultsThe study included 1,034 cases and 1,091 controls. Of the cases, 47% were Black, 54% were men, and the mean (±SD) age was 41.0 (±6.9) years. The odds of having a stroke increased exponentially as the number of risk factors increased, 2.1, 2.6, 7.6, 16.5, allp< 0.001, for groups 1–4, respectively. When stratified by race, Black individuals were approximately 6 times more likely to have all 4 risk factors.DiscussionThe risk of stroke in young adults increased exponentially with the number of risk factors. Young Black patients with ischemic stroke were approximately 6 times more likely to have the co-occurrence of obesity, hypertension, diabetes, and smoking compared with their White counterparts. Targeting public health interventions to identify and improve care to Black young adults with multiple stroke risk factors may have substantial impact on lowering risk of stroke.