Few studies have compared the proportion of ischemic strokes attributable to traditional vascular risk factors (population-attributable risk percent or PAR%) between genders and races. The PAR% is a function of the population prevalence and strength of association of a risk factor.

A population-based case-control study of ischemic stroke in young adults ages 18-49 in the Baltimore-Washington region was used to study the prevalence, odds ratios, and PAR% of hypertension, diabetes, and smoking among blacks and whites. Logistic regression was used to calculate age-adjusted odds ratios. All analyses were stratified by gender.

There were 1044 cases and 1099 controls. Of the cases, 47% were black, 54% were women. Roughly a quarter to a third of all strokes in women were attributable to smoking. Due to the higher prevalence of hypertension and a higher odds ratio for hypertension in black men (OR 3.9, 95% CI 2.6-5.9) compared to white men (OR 1.8, 95% CI 1.3-2.6), there was a much higher PAR% for hypertension among black men than white men.  

Traditional vascular risk factors have the potential to explain a high proportion of ischemic stroke in young adults. The high proportion of strokes in women attributable to smoking underscores the need for targeted smoking cessation interventions in this population. Diabetes and, especially, hypertension are important contributors to the excess population burden of ischemic stroke among blacks. These findings support the value of early screening and treatment for hypertension in young blacks.