title: Low levels of vitamin D are associated with increased mortality in patients attending a university hospital in Denmark.
abstract: BACKGROUND
  Increased mortality in patients with low serum concentrations of S-25(OH)D has been described, though no causal relationship has been shown. The aim of this cohort study was to investigate the possible association between S-25(OH)D status and all-cause mortality in 5,147 patients attending a university hospital in Denmark from 2003-2008.
  
  
  METHODS
  Serum was analyzed for ionized calcium (S-Ca(2+)), parathyroid hormone (S-PTH) and S-25(OH)D. Kaplan-Meier curves were used to analyze the association between S-25(OH)D quartiles, S-PTH-quartiles and all-cause mortality. Cox regression analyzed associations of age, gender, concentrations of ionized calcium, S-PTH and S-25(OH)D with all-cause mortality.
  
  
  RESULTS
  Log rank tests for both S-25(OH)D and S-PTH quartiles showed a significant difference across the quartiles. The Cox regression analysis showed a hazard ratio (HR) for death of 1.02 (95% CI: 1.01; 1.03) for S-PTH per pmol/L increase, 1.07 (95% CI: 1.05; 1.10) for S-25(OH)D per 10 nmol/L decrease and 0.54 (95% CI: 0.24; 1.20) for S-Ca(2+) per mmol/L increase.
  
  
  CONCLUSIONS
  This study supports growing evidence, that low serum concentrations of 25(OH)D are associated with an increased all-cause mortality; however the nature of the study prevents the finding of a causal relationship. In the Cox regression analysis S-25(OH)D concentrations in the blood were inversely associated with all-cause mortality. Prospective controlled studies are needed to confirm a causal relationship between low S-25(OH)D concentrations and mortality.
authors.affiliation: Department of Clinical Pharmacology, Bispebjerg Hospital, University of Copenhagen, Denmark.
authors.forename: Thalia M
authors.initials: TM
authors.lastname: Blicher
authors.forename: Henrik L
authors.initials: HL
authors.lastname: Jørgensen
authors.forename: Peter
authors.initials: P
authors.lastname: Schwarz
authors.forename: Hans C
authors.initials: HC
authors.lastname: Wulf
mesh_terms: D002118:Calcium / Q000097:blood; D003718:Denmark / Q000453:epidemiology; D017052:Hospital Mortality; D006785:Hospitals, University; D006801:Humans; D012307:Risk Factors; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood
chemical_list: D014807:Vitamin D; C104450:25-hydroxyvitamin D; D002118:Calcium