title: Estimation of the optimum dose of vitamin D for disease prevention in older people: rationale, design and baseline characteristics of the BEST-D trial.
abstract: BACKGROUND
  Previous large trials of vitamin D for prevention of fractures and other disease outcomes have reported conflicting results, possibly because the doses tested were insufficient to maintain optimum blood levels of vitamin D (25[OH]D) predicted by the observational studies. This report describes the design and baseline characteristics of the BEST-D (Biochemical Efficacy and Safety Trial of vitamin D) trial which aims to establish the best dose of vitamin D to assess in a future large outcome trial.
  
  
  METHODS
  The BEST-D trial will compare the biochemical and other effects of daily dietary supplementation with 100 μg or 50 μg vitamin D3 or placebo, when administered for 12 months, in 305 ambulant community-dwelling older people living in Oxfordshire, England. The primary analyses will compare 12-month mean plasma concentrations of 25(OH)D as well as the proportion of participants with a 12-month concentration >90 nmol/L between participants allocated 100 μg and participants allocated 50 μg daily. Secondary analyses will compare the two active doses (both separately and when combined) with placebo. Additional end-points include biochemical assessments of safety, blood pressure, arterial stiffness, falls, fractures, heel and wrist bone density, grip strength and physical performance and echocardiographic assessments of cardiac function in a random sample of participants.
  
  
  RESULTS
  About one-third of eligible participants agreed to participate in the trial. The mean age was 72 (SD 6) years with equal numbers of men and women. About one third reported a prior history of fracture or hypertension, one-fifth reported a prior cardiovascular event, and one tenth reported diabetes or a fall in the previous 6 months.
  
  
  CONCLUSIONS
  The results of this trial will help determine the optimum dose of vitamin D to test in a larger trial investigating whether vitamin D supplementation can reduce the risk of fractures, cardiovascular disease or cancer.
authors.affiliation: Clinical Trial Service Unit and Epidemiological Studies Unit, University of Oxford, Oxford, UK. Electronic address: Robert.clarke@ctsu.ox.ac.uk.
authors.forename: Robert
authors.initials: R
authors.lastname: Clarke
authors.affiliation: Division of Endocrinology & Metabolism, New York University School of Medicine, New York, NY, USA.
authors.forename: Connie
authors.initials: C
authors.lastname: Newman
authors.affiliation: Clinical Trial Service Unit and Epidemiological Studies Unit, University of Oxford, Oxford, UK.
authors.forename: Joseph
authors.initials: J
authors.lastname: Tomson
authors.affiliation: Hightown Surgery, Banbury, Oxfordshire, UK.
authors.forename: Harold
authors.initials: H
authors.lastname: Hin
authors.affiliation: Clinical Trial Service Unit and Epidemiological Studies Unit, University of Oxford, Oxford, UK.
authors.forename: Rijo
authors.initials: R
authors.lastname: Kurien
authors.affiliation: Clinical Trial Service Unit and Epidemiological Studies Unit, University of Oxford, Oxford, UK.
authors.forename: Jolyon
authors.initials: J
authors.lastname: Cox
authors.affiliation: Clinical Trial Service Unit and Epidemiological Studies Unit, University of Oxford, Oxford, UK.
authors.forename: Michael
authors.initials: M
authors.lastname: Lay
authors.affiliation: Clinical Trial Service Unit and Epidemiological Studies Unit, University of Oxford, Oxford, UK.
authors.forename: Jenny
authors.initials: J
authors.lastname: Sayer
authors.affiliation: Clinical Trial Service Unit and Epidemiological Studies Unit, University of Oxford, Oxford, UK.
authors.forename: Michael
authors.initials: M
authors.lastname: Hill
authors.affiliation: Clinical Trial Service Unit and Epidemiological Studies Unit, University of Oxford, Oxford, UK.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Emberson
authors.affiliation: Clinical Trial Service Unit and Epidemiological Studies Unit, University of Oxford, Oxford, UK.
authors.forename: Jane
authors.initials: J
authors.lastname: Armitage
mesh_terms: D000058:Accidental Falls / Q000517:prevention & control*; D000368:Aged; D001794:Blood Pressure / Q000187:drug effects; D015519:Bone Density / Q000187:drug effects; D050071:Bone Density Conservation Agents / Q000008:administration & dosage* / Q000009:adverse effects; D002762:Cholecalciferol / Q000008:administration & dosage* / Q000009:adverse effects; D019587:Dietary Supplements; D004452:Echocardiography; D005260:Female; D050723:Fractures, Bone / Q000517:prevention & control*; D018737:Hand Strength; D006321:Heart / Q000187:drug effects / Q000502:physiology; D006801:Humans; D008297:Male; D012107:Research Design; D059289:Vascular Stiffness / Q000187:drug effects; D014807:Vitamin D / Q000031:analogs & derivatives / Q000097:blood
chemical_list: D050071:Bone Density Conservation Agents; D014807:Vitamin D; D002762:Cholecalciferol; C104450:25-hydroxyvitamin D
keywords: 07034656; 25-Hydroxyvitamin D; EudraCT number: 2011-005763-24; Parathyroid hormone; Vitamin D supplementation trial