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 insufficiency and prognosis in chronic lymphocytic leukemia.
Vitamin D insufficiency is common globally and low levels are linked to higher cancer incidence . Although vitamin D insufficiency is related to inferior prognosis in some cancers , no data exist for chronic lymphocytic leukemia/small lymphocytic lymphoma ( CLL/SLL ) . We evaluated the relationship of 25(OH)D serum levels with time-to-treatment ( TTT ) and overall survival ( OS ) in newly diagnosed CLL patients participating in a prospect i ve cohort study ( discovery cohort ) and a separate cohort of previously untreated patients participating in an observational study ( confirmation cohort ) . Of 390 CLL patients in the discovery cohort , 119 ( 30.5 % ) were 25(OH)D insufficient . After a median follow-up of 3 years , TTT ( hazard ratio[HR ] = 1.66 ; P = .005 ) and OS ( HR = 2.39 ; P = .01 ) were shorter for 25(OH)D-insufficient patients . In the validation cohort , 61 of 153 patients ( 39.9 % ) were 25(OH)D insufficient . After a median follow-up of 9.9 years , TTT ( HR = 1.59 ; P = .05 ) and OS ( HR 1.63 ; P = .06 ) were again shorter for 25(OH)D-insufficient patients . On pooled multivariable analysis of patients in both cohorts adjusting for age , sex , Rai stage , CD38 status , ZAP-70 status , immunoglobulin heavy chain variable ( IGHV ) gene mutation status , CD49d status , and cytogenetic abnormalities assessed by interphase fluorescent in situ hybridization testing , 25(OH)D insufficiency remained an independent predictor of TTT ( HR = 1.47 ; P = .008 ) , although the association with OS was not significant ( HR = 1.47 ; P = .07 ) . Vitamin D insufficiency is associated with inferior TTT and OS in CLL patients . Whether normalizing vitamin D levels in deficient CLL patients would improve outcome merits clinical testing
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 .