Abstract 9478: Vitamin D Deficiency is Associated with Increased Risk of Fatal Stroke Among Whites but not Blacks: the NHANES-III Linked Mortality Files
Background: Vitamin D deficiency is associated with all-cause and cardiovascular disease (CVD) mortality. Prior data suggest racial differences in 25-hydroxyvitamin D [25(OH)D] levels may partially explain the excess risk of clinical CVD seen in blacks compared to whites. Both vitamin D deficiency and stroke are more prevalent among blacks. We examined whether vitamin D contributes to the excess risk of fatal stroke in blacks.
Methods: The Third National Health and Nutrition Examination Survey was a probability sample of US non-institutionalized civilians conducted between 1988–1994 (baseline). Data regarding 25(OH)D levels, demographics, and CVD risk factors was collected. Vital status through December 2006 was obtained via linkage with the National Death Index. Fatal stroke was defined as death from cerebrovascular disease (ICD-10 codes I60–I69). 25(OH)D levels <15 ng/mL were considered deficient. Among white and black adults without CHD or stroke reported at baseline (n=7981), Cox regression was used to estimate hazard ratios (HR) for fatal stroke by vitamin D status and race during a median of 14.1 years of follow-up.
Results: Mean 25(OH)D levels were significantly lower in blacks compared to whites (19.4 vs 30.8 ng/mL, respectively). In multivariable-adjusted models, the HR for fatal stroke associated with 25(OH)D deficiency was higher among whites, but not blacks (Table). In age and sex adjusted models, the HR for fatal stroke associated with black race compared with white race was 1.76 (1.19, 2.60) and was only modestly attenuated after further adjustment for socio-economic status and CVD risk factors [1.65 (1.07, 2.54)]. Further adjustment for 25(OH)D did not attenuate the HR for fatal stroke among blacks [1.69 (1.07, 2.69)].
Conclusions: Vitamin D deficiency may increase risk of stroke death in whites but not blacks. Although blacks had a higher rate of fatal stroke compared to whites, racial differences in 25(OH)D levels did not explain this excess risk.
- © 2010 by American Heart Association, Inc.