Abstract 16936: Vitamin D Supplementation Lowers Blood Pressure and Improves Control Rates in a Predominantly African American Hypertensive Cohort
Background: Vitamin D deficiency, highly prevalent in African Americans, has been associated with elevated blood pressure (BP) and hypertension in epidemiological studies. However, vitamin D supplementation has not been shown to consistently lower BP.
Methods: Six hundred forty eight hypertensive patients with vitamin D blood levels and BP above JNC goal levels, with at least one follow-up visit, were followed a median of 10.6 months (5 clinic visits). At baseline, mean age was 56.5 years, mean BP 156/92 mm Hg, (mean of 22.3/8.8 mm Hg above JNC BP goal), mean vitamin D level 17.6 ng/ml; 67.2% were women and 87.7% were African American. Mixed effects general linear models were used to estimate longitudinal BP changes. Cox proportional hazards models were used to estimate the impact of vitamin D supplementation on first attainment of JNC goal BP. Repeated event proportional hazards analysis was utilized to determine the incremental (per 1 category higher of vitamin D supplementation) likelihood of attainment of JNC goal BP during follow-up. Models were adjusted for age, sex, initial BP level, baseline vitamin D level (< 15, > 15 ng/ml), antihypertensive drug therapeutic intensity, and vitamin D supplementation (0 = no vitamin D, 1 = < 2000 IU/d, 2 = > 2000 IU/d); the latter two variables were entered into the models as time-varying covariates.
Results: Relative to no vitamin D supplementation, longitudinal SBP change was - 3.9 (p = 0.0089) and - 10.7 mm Hg (p = 0.0003) greater at incrementally higher vitamin D supplementation; DBP change was -2.5 (p = 0.0042) and - 7.0 mm Hg (p < 0.0001) greater. Per 1 category higher vitamin D supplementation, there was no effect on first attainment of goal SBP HR = 1.15, 95% CI 0.94 - 1.39. However, first time DBP control was favorably impacted - HR = 1.28, 95% CI 1.09 - 1.50. Repeated events proportional hazards analysis showed greater BP control per 1 category higher vitamin D supplementation (SBP goal HR = 1.32, 95% CI 1.21 - 1.44; DBP goal HR =1.30, 95% CI 1.20 - 1.41).
Conclusion: Vitamin D supplementation appears to lower BP and improve BP control rates independent of the intensity of antihypertensive treatment in a dose-dependent manner. The BP lowering effect is, however, most pronounced at > 2000 IU/d.
- © 2011 by American Heart Association, Inc.