title: Vitamin D and subsequent all-age and premature mortality: a systematic review.
abstract: BACKGROUND
  All-cause mortality in the population<65 years is 30% higher in Glasgow than in equally deprived Liverpool and Manchester. We investigated a hypothesis that low vitamin D in this population may be associated with premature mortality via a systematic review and meta-analysis.
  
  
  METHODS
  Medline, EMBASE, Web of Science, the Cochrane Library and grey literature sources were searched until February 2012 for relevant studies. Summary statistics were combined in an age-stratified meta-analysis.
  
  
  RESULTS
  Nine studies were included in the meta-analysis, representing 24,297 participants, 5,324 of whom died during follow-up. The pooled hazard ratio for low compared to high vitamin D demonstrated a significant inverse association (HR 1.19, 95% CI 1.12-1.27) between vitamin D levels and all-cause mortality after adjustment for available confounders. In an age-stratified meta-analysis, the hazard ratio for older participants was 1.25 (95% CI 1.14-1.36) and for younger participants 1.12 (95% CI 1.01-1.24).
  
  
  CONCLUSIONS
  Low vitamin D status is inversely associated with all-cause mortality but the risk is higher amongst older individuals and the relationship is prone to residual confounding. Further studies investigating the association between vitamin D deficiency and all-cause mortality in younger adults with adjustment for all important confounders (or using randomised trials of supplementation) are required to clarify this relationship.
authors.affiliation: NHS Greater Glasgow and Clyde, G12 0XH, Scotland. lynne.rush@nhs.net.
authors.forename: Lynne
authors.initials: L
authors.lastname: Rush
authors.forename: Gerry
authors.initials: G
authors.lastname: McCartney
authors.forename: David
authors.initials: D
authors.lastname: Walsh
authors.forename: Daniel
authors.initials: D
authors.lastname: MacKay
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D061213:Mortality, Premature; D006113:United Kingdom / Q000453:epidemiology; D014808:Vitamin D Deficiency / Q000401:mortality*