title: Association of serum vitamin B12 and folate with mortality in incident hemodialysis patients.
abstract: BACKGROUND
  Vitamin B12 (B12) and folate are essential vitamins that play important roles in physiological processes. In the general population, many studies have evaluated the association of these vitamins with clinical outcomes, yet this association in hemodialysis (HD) patients remains unclear.
  
  
  METHODS
  We examined the association of serum folate and B12 with mortality in a 5-year cohort of 9517 (folate) and 12 968 (B12) HD patients using Cox models with hierarchical adjustment for sociodemographics, comorbidities, and laboratory variables associated with the malnutrition and inflammation complex syndrome. The associations of baseline B12 and folate (separately) with all-cause mortality were evaluated across five categories of B12 [<400 (reference), 400-<550, 550-<650, 650-<750 and ≥750 pg/mL] and folate [<6.2, 6.2-<8.4, 8.4-<11 (reference), 11-<14.3 and ≥14.3 ng/mL].
  
  
  RESULTS
  The study cohort with B12 measurements had a mean ± standard deviation age of 63 ± 15 years, among whom 43% were female, 33% were African-American, and 57% were diabetic. Higher B12 concentrations ≥550 pg/mL were associated with a higher risk of mortality after adjusting for sociodemographic and laboratory variables. However, only lower serum folate concentrations <6.2 ng/mL were associated with a higher risk of all-cause mortality when adjusted for sociodemographic variables [adjusted hazard ratio (95% confidence-interval): 1.18 (1.03-1.35)].
  
  
  CONCLUSIONS
  Higher B12 concentrations are associated with higher all-cause mortality in HD patients independent of sociodemographics and laboratory variables, whereas lower folate concentrations were associated with higher all-cause mortality after accounting for sociodemographic variables. Further studies are warranted to determine the optimal B12 and folate level targets in this population.
authors.affiliation: Division of Nephrology & Hypertension, Harold Simmons Center for Kidney Disease Research and Epidemiology, University of California Irvine, School of Medicine, Orange, CA, USA.
authors.forename: Melissa
authors.initials: M
authors.lastname: Soohoo
authors.affiliation: Division of Nephrology & Hypertension, Harold Simmons Center for Kidney Disease Research and Epidemiology, University of California Irvine, School of Medicine, Orange, CA, USA.
authors.forename: Seyed-Foad
authors.initials: SF
authors.lastname: Ahmadi
authors.affiliation: Division of Nephrology & Hypertension, Harold Simmons Center for Kidney Disease Research and Epidemiology, University of California Irvine, School of Medicine, Orange, CA, USA.
authors.forename: Hemn
authors.initials: H
authors.lastname: Qader
authors.affiliation: Division of Nephrology & Hypertension, Harold Simmons Center for Kidney Disease Research and Epidemiology, University of California Irvine, School of Medicine, Orange, CA, USA.
authors.forename: Elani
authors.initials: E
authors.lastname: Streja
authors.affiliation: Division of Nephrology & Hypertension, Harold Simmons Center for Kidney Disease Research and Epidemiology, University of California Irvine, School of Medicine, Orange, CA, USA.
authors.forename: Yoshitsugu
authors.initials: Y
authors.lastname: Obi
authors.affiliation: Division of Nephrology & Hypertension, Harold Simmons Center for Kidney Disease Research and Epidemiology, University of California Irvine, School of Medicine, Orange, CA, USA.
authors.forename: Hamid
authors.initials: H
authors.lastname: Moradi
authors.affiliation: Division of Nephrology & Hypertension, Harold Simmons Center for Kidney Disease Research and Epidemiology, University of California Irvine, School of Medicine, Orange, CA, USA.
authors.forename: Connie M
authors.initials: CM
authors.lastname: Rhee
authors.affiliation: Division of Nephrology & Hypertension, Harold Simmons Center for Kidney Disease Research and Epidemiology, University of California Irvine, School of Medicine, Orange, CA, USA.|Department of Medicine, Inje University, Busan, South Korea.
authors.forename: Tae Hee
authors.initials: TH
authors.lastname: Kim
authors.affiliation: Division of Nephrology, University of Tennessee Health Science Center, Memphis TN, USA, and Nephrology Section, Memphis Veterans Affairs Medical Center, Memphis, TN, USA.
authors.forename: Csaba P
authors.initials: CP
authors.lastname: Kovesdy
authors.affiliation: Division of Nephrology & Hypertension, Harold Simmons Center for Kidney Disease Research and Epidemiology, University of California Irvine, School of Medicine, Orange, CA, USA.
authors.forename: Kamyar
authors.initials: K
authors.lastname: Kalantar-Zadeh
mesh_terms: D000368:Aged; D005260:Female; D005492:Folic Acid / Q000097:blood*; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D016016:Proportional Hazards Models; D006435:Renal Dialysis; D051437:Renal Insufficiency / Q000097:blood* / Q000401:mortality / Q000628:therapy; D012306:Risk; D014805:Vitamin B 12 / Q000097:blood*
chemical_list: D005492:Folic Acid; D014805:Vitamin B 12
keywords: folate; hemodialysis; mortality; nutrition; vitamin B12