Serum 25-hydroxyvitamin D levels and all-cause and cardiovascular disease mortality among US adults with hypertension: the NHANES linked mortality study.

OBJECTIVES: Research suggests that serum concentrations of 25-hydroxyvitamin D [25(OH)D] are inversely associated with hypertension incidence. This study examined whether concentrations of 25(OH)D are inversely associated with mortality risk among US adults with hypertension.
METHODS: We analyzed data from the 2001-2004 National Health and Nutrition Examination Survey with mortality data obtained through 2006. Hazard ratios with 95% confidence intervals (CIs) for all-cause and cardiovascular disease (CVD) mortality were estimated using Cox proportional hazard models.
RESULTS: Of 2609 participants with hypertension, 191 died (including 68 CVD deaths) during an average of 3.7-year follow-up. Compared with participants with 25(OH)D concentrations in the highest quartile (≥29 ng/ml), the hazard ratios for all-cause mortality were 1.93 (95% CI 1.06-3.49), 1.32 (95% CI 0.85-2.04), and 1.36 (95% CI 0.84-2.22), respectively (P for trend <0.05), and the hazard ratios for CVD mortality were 3.21 (95% CI 1.14-8.99), 2.42 (95% CI 0.85-6.90), and 2.33 (95% CI 0.88-6.12), respectively (P for trend <0.05), in the first (<17 ng/ml), second (17-<23 ng/ml) and third (23-<29 ng/ml) quartiles of 25(OH)D after adjustment for potential confounding variables. Additionally, concentrations of 25(OH)D as a continuous variable were linearly and inversely associated with the risk of mortality from all causes (P = 0.012) and from CVD (P = 0.010). These relationships were not affected much by adjustment for baseline blood pressure and use of antihypertension medications.
CONCLUSION: Concentrations of 25(OH)D were inversely associated with all-cause and CVD mortality among adults with hypertension in the US. Enhancing vitamin D intake may contribute to a lower risk for premature death.