title: Vitamin D supplementation in the management of knee osteoarthritis: study protocol for a randomized controlled trial.
abstract: BACKGROUND
  Osteoarthritis (OA) is a common health issue worldwide in the aging population who are also commonly deficient in vitamin D. Our previous study suggested that higher serum 25-(OH)D levels were associated with reduced knee cartilage loss, implying that vitamin D supplementation may prevent the progression of knee OA. The aim of the VItamin D Effects on OA (VIDEO) study is to compare, over a 2- year period, the effects of vitamin D supplementation versus placebo on knee structural changes, knee pain, and lower limb muscle strength in patients with symptomatic knee OA.
  
  
  METHODS
  Randomised, placebo-controlled, and double-blind clinical trial aiming to recruit 400 subjects (200 from Tasmania and 200 from Victoria) with both symptomatic knee OA and vitamin D deficiency (serum [25-(OH)D] level of >12.5 nmol/liter and <60 nmol/liter). Participants will be randomly allocated to vitamin D supplementation (50,000 IU compounded vitamin D3 capsule monthly) or identical inert placebo group for 2 years. The primary endpoint is loss of knee cartilage volume measured by magnetic resonance imaging (MRI) and Western Ontario and McMaster Universities Index of OA (WOMAC) knee pain score. The secondary endpoints will be other knee structural changes, and lower limb muscle strength. Several other outcome measures including core muscle images and central blood pressure will be recorded. Linear and logistic regression will be used to compare changes between groups using univariable and multivariable modeling analyses. Both intention to treat and per protocol analyses will be utilized.
  
  
  CONCLUSIONS
  The trial is designed to test if vitamin D supplementation will reduce loss of knee cartilage volume, prevent the progression of other knee structural abnormalities, reduce knee pain and strengthen lower limb muscle strength, thus modify disease progression in knee OA.
  
  
  BACKGROUND
  ClinicalTrials.gov identifier: NCT01176344; Australian New Zealand Clinical Trials Registry: ACTRN12610000495022.
authors.affiliation: Menzies Research Institute Tasmania, University of Tasmania, Private Bag 23, Hobart, TAS, 7000, Australia.
authors.forename: Yuelong
authors.initials: Y
authors.lastname: Cao
authors.forename: Graeme
authors.initials: G
authors.lastname: Jones
authors.forename: Flavia
authors.initials: F
authors.lastname: Cicuttini
authors.forename: Tania
authors.initials: T
authors.lastname: Winzenberg
authors.forename: Anita
authors.initials: A
authors.lastname: Wluka
authors.forename: James
authors.initials: J
authors.lastname: Sharman
authors.forename: Kay
authors.initials: K
authors.lastname: Nguo
authors.forename: Changhai
authors.initials: C
authors.lastname: Ding
mesh_terms: D018771:Arthralgia / Q000188:drug therapy / Q000473:pathology; D050071:Bone Density Conservation Agents / Q000008:administration & dosage*; D018450:Disease Progression; D004311:Double-Blind Method; D006801:Humans; D008279:Magnetic Resonance Imaging; D053580:Muscle Strength / Q000187:drug effects; D020370:Osteoarthritis, Knee / Q000188:drug therapy* / Q000473:pathology; D010919:Placebos; D012107:Research Design; D013648:Tasmania; D016896:Treatment Outcome; D014739:Victoria; D014807:Vitamin D / Q000008:administration & dosage*; D014808:Vitamin D Deficiency / Q000188:drug therapy; D014815:Vitamins / Q000008:administration & dosage*
chemical_list: D050071:Bone Density Conservation Agents; D010919:Placebos; D014815:Vitamins; D014807:Vitamin D