Association of serum 25-hydroxyvitamin D concentrations with all-cause and cardiovascular mortality among US adults with prehypertension: a prospective cohort study

Background Prehypertension affects 25-50% of adults worldwide and no prior study has examined the relationship between serum 25-hydroxyvitamin D [25(OH)D] concentrations and mortality risk in individuals with prehypertension. This study aims to investigate the association of serum 25(OH)D concentrations with all-cause and CVD mortality among prehypertensive adults by utilizing data from the US National Health and Nutrition Examination Survey (NHANES) 2007-2014 and linked 2019 mortality file. Methods We included 4345 prehypertensive adults who participated in the NHANES between 2007 and 2014 and were followed up until 31 December 2019. Weighted Cox proportional hazards models were used with adjustments for multiple covariates to calculate the hazard ratio (HR) and 95% confidence interval (CI) for the risks of dying from any cause and CVD. Results During a median follow-up of 8.8 years, 335 deaths from any causes were documented, of which 88 participants died from CVD. Compared with participants with sufficient 25(OH)D (>= 75 nmol/L), the multivariate-adjusted HRs and 95% CIs for participants with severe deficiency (< 25 nmol/L), moderate deficiency (25-49.9 nmol/L), and insufficient concentrations (50-74.9 nmol/L) of serum 25(OH)D for all-cause death were 2.83 (1.46-5.52), 1.17 (0.74-1.86), and 1.36 (0.93-1.98), respectively. Similarly, the multivariable-adjusted HRs and 95%CIs for CVD death were 4.14 (1.10-15.51), 1.23 (0.46-3.28), and 1.73 (0.96-3.14), respectively. We found that there was a 9% reduction in the risk of death from all causes and a 14% reduction in the risk of death from CVD for every 10 nmol/L increase in serum 25(OH)D concentrations. Conclusion Severe serum 25(OH)D deficiency among prehypertensive adults was associated with increased risk of mortality from all causes as well as from CVD. Our work suggests that supplementing with vitamin D may prevent premature death in severely deficient individuals with prehypertension.