Mortality 36% higher in those deficient in vitamin D
The risk for mortality was a significant 36% higher for participants with 25-(OH)D 25 nmol/L compared with 50 nmol/L.
With the Mendelian randomization, there was an L-shaped association between genetically predicted 25-(OH)D level and all-cause mortality (P for nonlinearity < .001) and for mortality because of cancer and cardiovascular disease (P for nonlinearity ≤ .033).
Again, the strongest association with those outcomes and genetically predicted 25-(OH)D was found at levels below 25 nmol/L and a plateau was seen by 50 nmol/L.
Compared with a measured 25-(OH)D concentration of 50 nmol/L, investigators estimated that the genetically predicted odds of all-cause mortality would increase sixfold (odds ratio, 6.00) for participants at 10 nmol/L and by 25% (OR, 1.25) for those at 25 nmol/L.
And, compared with a measured 25-(OH)D concentration of 50 nmol/L, those with 10 nmol/L had genetically predicted odds ratios of 5.98 for cardiovascular mortality, 3.37 for cancer mortality, and 12.44 for respiratory mortality.
Comparing measured 25-(OH)D concentrations of 25 nmol/L versus 50 nmol/L, odds ratios for those outcomes were 1.25, 1.16, and 1.96 (95% confidence interval, 1.88-4.67), respectively. All were statistically significant.
Consistent results supportive of a causal effect of genetically predicted 25-(OH)D on all-cause mortality in those with low measured vitamin D concentrations were also found in a sensitivity analysis of 20,837 people of non-White ethnic origin.
The study was funded by the Australian National Health and Medical Research Council. Dr. Sutherland’s studentship is funded by an Australian Research Training Program Scholarship.
A version of this article first appeared on Medscape.com.