title: Serum 25-hydroxyvitamin D concentration and risk for major clinical disease events in a community-based population of older adults: a cohort study.
abstract: BACKGROUND
  Circulating concentrations of 25-hydroxyvitamin D [25-(OH)D] are used to define vitamin D deficiency. Current clinical 25-(OH)D targets based on associations with intermediate markers of bone metabolism may not reflect optimal levels for other chronic diseases and do not account for known seasonal variation in 25-(OH)D concentration.
  
  
  OBJECTIVE
  To evaluate the relationship of 25-(OH)D concentration with the incidence of major clinical disease events that are pathophysiologically relevant to vitamin D.
  
  
  METHODS
  Cohort study.
  
  
  METHODS
  The Cardiovascular Health Study conducted in 4 U.S. communities. Data from 1992 to 2006 were included in this analysis.
  
  
  METHODS
  1621 white older adults.
  
  
  METHODS
  Serum 25-(OH)D concentration (using a high-performance liquid chromatography-tandem mass spectrometry assay that conforms to National Institute of Standards and Technology reference standards) and associations with time to a composite outcome of incident hip fracture, myocardial infarction, cancer, or death.
  
  
  RESULTS
  Over a median 11-year follow-up, the composite outcome occurred in 1018 participants (63%). Defining events included 137 hip fractures, 186 myocardial infarctions, 335 incidences of cancer, and 360 deaths. The association of low 25-(OH)D concentration with risk for the composite outcome varied by season (P = 0.057). A concentration lower than a season-specific Z score of -0.54 best discriminated risk for the composite outcome and was associated with a 24% higher risk in adjusted analyses (95% CI, 9% to 42%). Corresponding season-specific 25-(OH)D concentrations were 43, 50, 61, and 55 nmol/L (17, 20, 24, and 22 ng/mL) in winter, spring, summer, and autumn, respectively.
  
  
  CONCLUSIONS
  The observational study was restricted to white participants.
  
  
  CONCLUSIONS
  Threshold concentrations of 25-(OH)D associated with increased risk for relevant clinical disease events center near 50 nmol/L (20 ng/mL). Season-specific targets for 25-(OH)D concentration may be more appropriate than static targets when evaluating health risk.
  
  
  BACKGROUND
  National Institutes of Health.
authors.affiliation: University of Washington, Seattle, USA. deboer@u.washington.edu
authors.forename: Ian H
authors.initials: IH
authors.lastname: de Boer
authors.forename: Gregory
authors.initials: G
authors.lastname: Levin
authors.forename: Cassianne
authors.initials: C
authors.lastname: Robinson-Cohen
authors.forename: Mary L
authors.initials: ML
authors.lastname: Biggs
authors.forename: Andy N
authors.initials: AN
authors.lastname: Hoofnagle
authors.forename: David S
authors.initials: DS
authors.lastname: Siscovick
authors.forename: Bryan
authors.initials: B
authors.lastname: Kestenbaum
mesh_terms: D000368:Aged; D002423:Cause of Death; D005260:Female; D005500:Follow-Up Studies; D006620:Hip Fractures / Q000453:epidemiology*; D006801:Humans; D008297:Male; D009203:Myocardial Infarction / Q000453:epidemiology*; D009369:Neoplasms / Q000453:epidemiology*; D016016:Proportional Hazards Models; D018570:Risk Assessment; D012307:Risk Factors; D012621:Seasons; D014481:United States / Q000453:epidemiology; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood; D014808:Vitamin D Deficiency / Q000097:blood / Q000150:complications*
chemical_list: D014807:Vitamin D; C104450:25-hydroxyvitamin D