Subgroup analyses in the observational studies indicated that risk of mortality was significantly higher in studies with lower baseline use of vitamin D supplements .
The effects observed for vitamin D3 supplementation remained unchanged when grouped by various characteristics .
However , for vitamin D2 supplementation , increased risks of mortality were observed in studies with lower intervention doses and shorter average intervention periods .
Conclusions Evidence from observational studies indicates inverse associations of circulating 25-hydroxyvitamin D with risks of death due to cardiovascular disease , cancer , and other causes .
Objective To evaluate the extent to which circulating biomarker and supplements of vitamin D are associated with  mortality from cardiovascular , cancer , or other conditions  , under various circumstances .
Impact of Hypovitaminosis D and Alfacalcidol Therapy on Survival of Hemodialysis Patients: Results from the French ARNOS Study
Background : In chronic kidney disease and dialysis patients , vitamin D deficiency is associated with mortality . In some observational studies , calcitriol analogue therapy was associated with a better survival rate in hemodialysis ( HD ) patients . The aim of this study was to determine the relationship between serum 25-hydroxyvitamin D ( 25-OHD ) levels and alfacalcidol therapy with HD patients ’ outcomes . Methods : We measured baseline 25-OHD levels using a cross-sectional analysis in 648 HD prevalent patients from the regional ARNOS French cohort . A 42-month survival analysis was applied according to serum 25-OHD level and calcitriol analogue therapy . Results : The prevalence of 25-OHD insufficiency < 30 ng/ml was high ( 73 % ) , with only 22 % taking native vitamin D supplementation . A baseline 25-OHD level above the median value ( 18 ng/ml ) was associated with lower all-cause mortality [ hazard ratio ( HR ) , 0.73 ( 0.5–0.96 ) ; p = 0.02 ] after adjustment for age , gender , dialysis vintage , calcemia , phosphatemia , cardiovascular disease , and diabetes . Only in monovariate analysis was low-dose oral alfacalcidol therapy associated with a better survival rate in patients with and without 25-OHD deficiency [ HR , 0.7 ( 0.5–0.92 ) ; p = 0.05 ] . Conclusions : Our study shows that , among prevalent HD patients , low 25-OHD levels affect  mortality .  Alfacalcidol therapy , especially in small doses , may provide compensation , but this needs to be further confirmed using prospect i ve controlled studies comparing native and active vitamin D compounds
Subgroup analyses in the observational studies indicated that risk of mortality was significantly higher in studies with lower baseline use of vitamin D supplements .
The effects observed for vitamin D3 supplementation remained unchanged when grouped by various characteristics .
However , for vitamin D2 supplementation , increased risks of mortality were observed in studies with lower intervention doses and shorter average intervention periods .
Conclusions Evidence from observational studies indicates inverse associations of circulating 25-hydroxyvitamin D with risks of death due to cardiovascular disease , cancer , and other causes .
Objective To evaluate the extent to which circulating biomarker and supplements of vitamin D are associated with  mortality from cardiovascular , cancer , or other conditions  , under various circumstances .