title: Vitamin D deficiency and mortality in patients receiving dialysis: the Comprehensive Dialysis Study.
abstract: OBJECTIVE
  Although several studies have shown poorer survival among individuals with 25-hydroxy (OH) vitamin D deficiency, data on patients receiving dialysis are limited. Using data from the Comprehensive Dialysis Study (CDS), we tested the hypothesis that patients new to dialysis with low serum concentrations of 25-OH vitamin D would experience higher mortality and hospitalizations.
  
  
  METHODS
  The CDS is a prospective cohort study.We recruited participants from 56 dialysis units located throughout the United States.
  
  
  METHODS
  We obtained data on demographics, comorbidites, and laboratory values from the CDS Patient Questionnaire as well as the Medical Evidence Form (CMS form 2728). Participants provided baseline serum samples for 25-OH vitamin D measurements.
  
  
  METHODS
  We ascertained time to death and first hospitalization as well as number of first-year hospitalizations via the U.S. Renal Data System standard analysis files. We used Cox proportional hazards to determine the association between 25-OH vitamin D tertiles and survival and hospitalization. For number of hospitalizations in the first year, we used negative binomial regression.
  
  
  RESULTS
  The analytic cohort was composed of 256 patients with Patient Questionnaire data and 25-OH vitamin D concentrations. The mean age of participants was 62 (±14.0) years, and mean follow-up was 3.8 years. Patients with 25-OH vitamin D concentrations in the lowest tertile (<10.6 ng/mL) at the start of dialysis experienced higher mortality (adjusted hazard ratio 1.75, 95% confidence interval [CI] 1.03-2.97) as well as hospitalization (adjusted hazard ratio 1.76, 95% CI 1.24-2.49). Patients in the lower 2 tertiles (<15.5 ng/mL) experienced a higher rate of hospitalizations in the first year (incidence rate ratio 1.70 [95% CI 1.06-2.72] for middle tertile, 1.66 [95% CI 1.10-2.51] for lowest tertile).
  
  
  CONCLUSIONS
  We found a sizeable increase in mortality and hospitalization for patients on dialysis with severe 25-OH vitamin D deficiency.
authors.affiliation: Division of Nephrology, Department of Medicine, Stanford University School of Medicine, Palo Alto, California. Electronic address: sanand2@stanford.edu.
authors.forename: Shuchi
authors.initials: S
authors.lastname: Anand
authors.forename: Glenn M
authors.initials: GM
authors.lastname: Chertow
authors.forename: Kirsten L
authors.initials: KL
authors.lastname: Johansen
authors.forename: Barbara
authors.initials: B
authors.lastname: Grimes
authors.forename: Lorien S
authors.initials: LS
authors.lastname: Dalrymple
authors.forename: George A
authors.initials: GA
authors.lastname: Kaysen
authors.forename: Manjula
authors.initials: M
authors.lastname: Kurella Tamura
mesh_terms: D000368:Aged; D005260:Female; D006760:Hospitalization / Q000706:statistics & numerical data; D006801:Humans; D008297:Male; D008875:Middle Aged; D006435:Renal Dialysis / Q000401:mortality*; D014481:United States; D014807:Vitamin D / Q000031:analogs & derivatives / Q000097:blood; D014808:Vitamin D Deficiency / Q000097:blood / Q000150:complications* / Q000401:mortality
chemical_list: D014807:Vitamin D; C104450:25-hydroxyvitamin D