title: What is the optimal level of vitamin D in non-dialysis chronic kidney disease population?
abstract: OBJECTIVE
  To evaluate thresholds for serum 25(OH)D concentrations in relation to death, kidney progression and hospitalization in non-dialysis chronic kidney disease (CKD) population.
  
  
  METHODS
  Four hundred and seventy non-dialysis 3-5 stage CKD patients participating in OSERCE-2 study, a prospective, multicenter, cohort study, were prospectively evaluated and categorized into 3 groups according to 25(OH)D levels at enrollment (less than 20 ng/mL, between 20 and 29 ng/mL, and at or above 30 ng/mL), considering 25(OH)D between 20 and 29 ng/mL as reference group. Association between 25(OH)D levels and death (primary outcome), and time to first hospitalization and renal progression (secondary outcomes) over a 3-year follow-up, were assessed by Kaplan-Meier survival curves and Cox-proportional hazard models. To identify 25(OH)D levels at highest risk for outcomes, receiver operating characteristic (ROC) curves were performed.
  
  
  RESULTS
  Over 29 ± 12 mo of follow-up, 46 (10%) patients dead, 156 (33%) showed kidney progression, and 126 (27%) were hospitalized. After multivariate adjustment, 25(OH)D < 20 ng/mL was an independent predictor of all-cause mortality (HR = 2.33; 95%CI: 1.10-4.91; P = 0.027) and kidney progression (HR = 2.46; 95%CI: 1.63-3.71; P < 0.001), whereas the group with 25(OH)D at or above 30 ng/mL did not have a different hazard for outcomes from the reference group. Hospitalization outcomes were predicted by 25(OH) levels (HR = 0.98; 95%CI: 0.96-1.00; P = 0.027) in the unadjusted Cox proportional hazards model, but not after multivariate adjusting. ROC curves identified 25(OH)D levels at highest risk for death, kidney progression, and hospitalization, at 17.4 ng/mL [area under the curve (AUC) = 0.60; 95%CI: 0.52-0.69; P = 0.027], 18.6 ng/mL (AUC = 0.65; 95%CI: 0.60-0.71; P < 0.001), and 19.0 ng/mL (AUC = 0.56; 95%CI: 0.50-0.62; P = 0.048), respectively.
  
  
  CONCLUSIONS
  25(OH)D < 20 ng/mL was an independent predictor of death and progression in patients with stage 3-5 CKD, with no additional benefits when patients reached the levels at or above 30 ng/mL suggested as optimal by CKD guidelines.
authors.affiliation: Pablo Molina, Sandra Beltrán, Belén Vizcaíno, Verónica Escudero, Julia Kanter, Ana I Ávila, José L Górriz, Luis M Pallardó, Department of Nephrology, Dr Peset University Hospital, 46017 Valencia, Spain.
authors.forename: Pablo
authors.initials: P
authors.lastname: Molina
authors.affiliation: Pablo Molina, Sandra Beltrán, Belén Vizcaíno, Verónica Escudero, Julia Kanter, Ana I Ávila, José L Górriz, Luis M Pallardó, Department of Nephrology, Dr Peset University Hospital, 46017 Valencia, Spain.
authors.forename: José L
authors.initials: JL
authors.lastname: Górriz
authors.affiliation: Pablo Molina, Sandra Beltrán, Belén Vizcaíno, Verónica Escudero, Julia Kanter, Ana I Ávila, José L Górriz, Luis M Pallardó, Department of Nephrology, Dr Peset University Hospital, 46017 Valencia, Spain.
authors.forename: Mariola D
authors.initials: MD
authors.lastname: Molina
authors.affiliation: Pablo Molina, Sandra Beltrán, Belén Vizcaíno, Verónica Escudero, Julia Kanter, Ana I Ávila, José L Górriz, Luis M Pallardó, Department of Nephrology, Dr Peset University Hospital, 46017 Valencia, Spain.
authors.forename: Sandra
authors.initials: S
authors.lastname: Beltrán
authors.affiliation: Pablo Molina, Sandra Beltrán, Belén Vizcaíno, Verónica Escudero, Julia Kanter, Ana I Ávila, José L Górriz, Luis M Pallardó, Department of Nephrology, Dr Peset University Hospital, 46017 Valencia, Spain.
authors.forename: Belén
authors.initials: B
authors.lastname: Vizcaíno
authors.affiliation: Pablo Molina, Sandra Beltrán, Belén Vizcaíno, Verónica Escudero, Julia Kanter, Ana I Ávila, José L Górriz, Luis M Pallardó, Department of Nephrology, Dr Peset University Hospital, 46017 Valencia, Spain.
authors.forename: Verónica
authors.initials: V
authors.lastname: Escudero
authors.affiliation: Pablo Molina, Sandra Beltrán, Belén Vizcaíno, Verónica Escudero, Julia Kanter, Ana I Ávila, José L Górriz, Luis M Pallardó, Department of Nephrology, Dr Peset University Hospital, 46017 Valencia, Spain.
authors.forename: Julia
authors.initials: J
authors.lastname: Kanter
authors.affiliation: Pablo Molina, Sandra Beltrán, Belén Vizcaíno, Verónica Escudero, Julia Kanter, Ana I Ávila, José L Górriz, Luis M Pallardó, Department of Nephrology, Dr Peset University Hospital, 46017 Valencia, Spain.
authors.forename: Ana I
authors.initials: AI
authors.lastname: Ávila
authors.affiliation: Pablo Molina, Sandra Beltrán, Belén Vizcaíno, Verónica Escudero, Julia Kanter, Ana I Ávila, José L Górriz, Luis M Pallardó, Department of Nephrology, Dr Peset University Hospital, 46017 Valencia, Spain.
authors.forename: Jordi
authors.initials: J
authors.lastname: Bover
authors.affiliation: Pablo Molina, Sandra Beltrán, Belén Vizcaíno, Verónica Escudero, Julia Kanter, Ana I Ávila, José L Górriz, Luis M Pallardó, Department of Nephrology, Dr Peset University Hospital, 46017 Valencia, Spain.
authors.forename: Elvira
authors.initials: E
authors.lastname: Fernández
authors.affiliation: Pablo Molina, Sandra Beltrán, Belén Vizcaíno, Verónica Escudero, Julia Kanter, Ana I Ávila, José L Górriz, Luis M Pallardó, Department of Nephrology, Dr Peset University Hospital, 46017 Valencia, Spain.
authors.forename: Javier
authors.initials: J
authors.lastname: Nieto
authors.affiliation: Pablo Molina, Sandra Beltrán, Belén Vizcaíno, Verónica Escudero, Julia Kanter, Ana I Ávila, José L Górriz, Luis M Pallardó, Department of Nephrology, Dr Peset University Hospital, 46017 Valencia, Spain.
authors.forename: Secundino
authors.initials: S
authors.lastname: Cigarrán
authors.affiliation: Pablo Molina, Sandra Beltrán, Belén Vizcaíno, Verónica Escudero, Julia Kanter, Ana I Ávila, José L Górriz, Luis M Pallardó, Department of Nephrology, Dr Peset University Hospital, 46017 Valencia, Spain.
authors.forename: Enrique
authors.initials: E
authors.lastname: Gruss
authors.affiliation: Pablo Molina, Sandra Beltrán, Belén Vizcaíno, Verónica Escudero, Julia Kanter, Ana I Ávila, José L Górriz, Luis M Pallardó, Department of Nephrology, Dr Peset University Hospital, 46017 Valencia, Spain.
authors.forename: Gema
authors.initials: G
authors.lastname: Fernández-Juárez
authors.affiliation: Pablo Molina, Sandra Beltrán, Belén Vizcaíno, Verónica Escudero, Julia Kanter, Ana I Ávila, José L Górriz, Luis M Pallardó, Department of Nephrology, Dr Peset University Hospital, 46017 Valencia, Spain.
authors.forename: Alberto
authors.initials: A
authors.lastname: Martínez-Castelao
authors.affiliation: Pablo Molina, Sandra Beltrán, Belén Vizcaíno, Verónica Escudero, Julia Kanter, Ana I Ávila, José L Górriz, Luis M Pallardó, Department of Nephrology, Dr Peset University Hospital, 46017 Valencia, Spain.
authors.forename: Juan F
authors.initials: JF
authors.lastname: Navarro-González
authors.affiliation: Pablo Molina, Sandra Beltrán, Belén Vizcaíno, Verónica Escudero, Julia Kanter, Ana I Ávila, José L Górriz, Luis M Pallardó, Department of Nephrology, Dr Peset University Hospital, 46017 Valencia, Spain.
authors.forename: Ramón
authors.initials: R
authors.lastname: Romero
authors.affiliation: Pablo Molina, Sandra Beltrán, Belén Vizcaíno, Verónica Escudero, Julia Kanter, Ana I Ávila, José L Górriz, Luis M Pallardó, Department of Nephrology, Dr Peset University Hospital, 46017 Valencia, Spain.
authors.forename: Luis M
authors.initials: LM
authors.lastname: Pallardó
keywords: Chronic kidney disease; Hospitalization; Mortality; Renal progression; Vitamin D