Vitamin D, Race, and Cardiovascular Mortality: Findings From a National US Sample

The Annals of Family Medicine
Q1
Jan 2010
Citations:159
Influential Citations:6
Observational Studies (Human)
80
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Enhanced Details

Methods
Retrospective cohort using NHANES III (1988-1994); adults aged 18+ with complete data (n = 15,363; weighted 90.8% of target); baseline serum 25(OH)D measured and quartiled; cardiovascular deaths followed through 2001 via the National Death Index; race/ethnicity categorized as white (non-Hispanic), black (non-Hispanic), Hispanic, and other; multiple covariates collected; analyses used Poisson regression with person-years, plus nested models to assess mediation by 25(OH)D and income.
Results
Low 25(OH)D (lowest quartile, mean 13.9 ng/mL) associated with higher cardiovascular mortality (adjusted IRR 1.40; 95% CI 1.16-1.70) versus higher quartiles (means 21.6, 28.4, 41.6 ng/mL). There is a threshold effect with little risk reduction above the 25th percentile. Excluding baseline cardiovascular morbidity yielded IRR 1.97 (95% CI 1.40-2.78). Blacks had higher cardiovascular mortality than whites in models with exogenous variables (IRR 1.38); adjusting for 25(OH)D reduced this to 1.14, and adding income eliminated it (IRR 1.01). Income and 25(OH)D had additive mediating effects. Findings suggest low vitamin D may contribute to black-white disparities in cardiovascular mortality. Interventional trials assessing whether vitamin D supplementation improves cardiovascular outcomes are needed, especially among Blacks; observational results are suggestive but not causal.
Limitations
Observational design limits causal inference; potential residual confounding and unmeasured factors; possible misclassification of cause of death; single baseline vitamin D measurement; data perturbations for confidentiality; results may not generalize beyond the US population.

Abstract

PURPOSE Findings are conflicting about the relationship between vitamin D levels and cardiovascular mortality. We wanted to determine the contribution of vitamin D levels to black-white disparities in cardiovascular mortality. METHODS We examined the...