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 .
Vitamin D deficiency in dialysis patients: effect of dialysis modality and implications on outcome.
OBJECTIVE Vitamin D deficiency has been linked to cardiovascular disease and mortality in hemodialysis ( HD ) patients . The purpose of the present cross-sectional study was to analyze the Vitamin D status of dialysis patients from a single center , study determinants of Vitamin D deficiency , and assess its implication s on outcome . METHODS A prospect i ve observational study of 115 prevalent dialysis patients was carried out , in which clinical and dialysis-related characteristics including routine biochemistry were studied in relation to levels of  25-hydroxyvitamin-D ( 25[OH]D , chemiluminescence )  . Survival was assessed after a median follow-up period of 413 days . RESULTS 25(OH)D deficiency and insufficiency was present in 51 % and 42 % of the patients , respectively . Only 7 % of the patients showed normal 25(OH)D levels .  Peritoneal dialysis  patients presented the lowest 25(OH)D levels . Also , a significant difference was found between on-line hemodiafiltration ( OL-HDF ) and conventional HD ( 11 [ 6 to 16 ] versus 19 [ 13 to 27 ] ng/mL ; P < 0.001 ; 25th to 75th percentiles , conventional HD versus OL-HDF respectively ) . In multinomial logistic regression analysis , patients on conventional HD had 8.35 greater odds ( 95 % CI [ 2.04 to 34.20 ] ) of 25(OH)D deficiency than OL-HDF even after adjustment for sex , parathyroid hormone , pH , and Charlson comorbidity index . During the follow-up period , 18 patients died . Both crude and adjusted ( hazard ratio , 6.96 ; 95 % CI [ 1.44 to 33.64 ] ) Cox analysis identified 25(OH)D deficiency as a mortality risk factor . CONCLUSION This observational study underlines the high prevalence of hypovitaminosis D in dialysis patients and its strong implication s on outcome . Furthermore , our results suggest that OL-HDF was associated with a better preservation of the vitamin D status as compared with conventional HD
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 .