SERUM FOLATE AND RISK FOR ISCHEMIC STROKE - FIRST NATIONAL-HEALTH AND NUTRITION EXAMINATION SURVEY EPIDEMIOLOGIC FOLLOW-UP-STUDY

Background and Purpose A serum folate concentration less than or equal to 9.2 nmol/L has been associated with elevated levels of plasma homocyst(e)ine. Elevated homocyst(e)ine levels have been associated with ischemic stroke in case-control studies; however, the results from prospective studies have been equivocal. We investigated whether a folate concentration less than or equal to 9.2 nmol/L was associated with ischemic stroke in a national cohort. Methods We used data from the First National Health and Nutrition Examination Survey Epidemiologic Follow-up Study (n=2006). Cox proportional hazards analyses were used to adjust for differences in follow-up time and covariates. During the PS-year follow-up, 98 ischemic strokes occurred. Results After adjusting for age, race, sex, education, diabetes, history of heart disease, systolic blood pressure, body mass index, hemoglobin level, cigarette smoking, and alcohol intake, participants with a folate concentration less than or equal to 9.2 nmol/L were at slightly increased risk for ischemic stroke (relative risk [RR], 1.37; 95% confidence interval [CI], 0.82 to 2.29). There was a folate-race interaction (P=.11 for interaction term). Whites with a folate concentration less than or equal to 9.2 nmol/L had a relative risk of 1.18 (95% CI, 0.67 to 2.08), whereas blacks had a relative risk of 3.60 (95% CI, 1.02 to 12.71). Conclusions These findings suggest that a folate concentration less than or equal to 9.2 nmol/L may be a risk factor for ischemic stroke, especially in blacks. However, given the small number of stroke events, additional studies are needed to assess the role of folate in the epidemiology of ischemic stroke.