Prospective study of serum 25-hydroxyvitamin D level, cardiovascular disease mortality, and all-cause mortality in older U.S. adults.J Am Geriatr Soc. 2009 Sep; 57(9):1595-603.JA
To evaluate the association between serum 25-hydroxyvitamin D (25(OH)D) levels and mortality in a representative U.S. sample of older adults.
Prospective cohort from the Third National Health and Nutrition Examination Survey (NHANES III) and linked mortality files.
Noninstitutionalized U.S. civilian population.
Three thousand four hundred eight NHANES III participants aged 65 and older enrolled from 1988 to 1994 and followed for mortality through 2000.
Primary exposure was serum 25(OH)D level at enrollment. Primary and secondary outcomes were all-cause and cardiovascular disease (CVD) mortality, respectively.
During the median 7.3 years of follow-up, there were 1,493 (44%) deaths, including 767 CVD-related deaths. Median 25(OH)D level was 66 nmol/L. Adjusting for demographics, season, and cardiovascular risk factors, baseline 25(OH)D levels were inversely associated with all-cause mortality risk (adjusted hazard ratio (HR)=0.95, 95% confidence interval (CI)=0.92-0.98, per 10 nmol/L 25[OH]D). Compared with subjects with 25(OH)D levels of 100 nmol/L or higher, the adjusted HR for subjects with levels less than 25.0 nmol/L was 1.83 (95% CI=1.14-2.94) and for levels of 25.0 to 49.9 nmol/L was 1.47 (95% CI=1.09-1.97). The association appeared stronger for CVD mortality (adjusted HR=2.36, 95% CI=1.17-4.75, for subjects with 25[OH]D levels<25.0 nmol/L vs those > or =100.0 nmol/L) than for non-CVD mortality (adjusted HR=1.42, 95% CI=0.73-2.79, for subjects with 25[OH]D levels<25.0 nmol/L vs those > or =100.0 nmol/L).
In noninstitutionalized older adults, a group at high risk for all-cause mortality, serum 25(OH)D levels had an independent, inverse association with CVD and all-cause mortality. Randomized controlled trials of vitamin D supplementation in older adults are warranted to determine whether this association is causal and reversible.