title: Double-blind randomised controlled trial of vitamin D3 supplementation for the prevention of acute respiratory infection in older adults and their carers (ViDiFlu).
abstract: BACKGROUND
  Low-dose vitamin D supplementation is already recommended in older adults for prevention of fractures and falls, but clinical trials investigating whether higher doses could provide additional protection against acute respiratory infection (ARI) are lacking.
  
  
  OBJECTIVE
  To conduct a clinical trial of high-dose versus low-dose vitamin D3 supplementation for ARI prevention in residents of sheltered-accommodation housing blocks ('schemes') and their carers in London, UK.
  
  
  METHODS
  Fifty-four schemes (137 individual participants) were allocated to the active intervention (vitamin D3 2.4 mg once every 2 months +10 μg daily for residents, 3 mg once every 2 months for carers), and 54 schemes with 103 participants were allocated to control (placebo once every 2 months +vitamin D3 10 μg daily for residents, placebo once every 2 months for carers) for 1 year. Primary outcome was time to first ARI; secondary outcomes included time to first upper/lower respiratory infection (URI/LRI, analysed separately), and symptom duration.
  
  
  RESULTS
  Inadequate vitamin D status was common at baseline: 220/240 (92%) participants had serum 25(OH)D concentration <75 nmol/L. The active intervention did not influence time to first ARI (adjusted HR (aHR) 1.18, 95% CI 0.80 to 1.74, p=0.42). When URI and LRI were analysed separately, allocation to the active intervention was associated with increased risk of URI (aHR 1.48, 95% CI 1.02 to 2.16, p=0.039) and increased duration of URI symptoms (median 7.0 vs 5.0 days for active vs control, adjusted ratio of geometric means 1.34, 95% CI 1.09 to 1.65, p=0.005), but not with altered risk or duration of LRI.
  
  
  CONCLUSIONS
  Addition of intermittent bolus-dose vitamin D3 supplementation to a daily low-dose regimen did not influence risk of ARI in older adults and their carers, but was associated with increased risk and duration of URI.
  
  
  BACKGROUND
  clinicaltrials.gov NCT01069874.
authors.affiliation: Centre for Primary Care and Public Health, Blizard Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, UK Asthma UK Centre for Applied Research, Blizard Institute, Queen Mary University of London, London, UK.
authors.forename: Adrian R
authors.initials: AR
authors.lastname: Martineau
authors.affiliation: London School of Hygiene and Tropical Medicine, London, UK.
authors.forename: Yasmeen
authors.initials: Y
authors.lastname: Hanifa
authors.affiliation: Centre for Primary Care and Public Health, Blizard Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, UK.
authors.forename: Karolina D
authors.initials: KD
authors.lastname: Witt
authors.affiliation: Centre for Primary Care and Public Health, Blizard Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, UK.
authors.forename: Neil C
authors.initials: NC
authors.lastname: Barnes
authors.affiliation: Centre for Primary Care and Public Health, Blizard Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, UK.
authors.forename: Richard L
authors.initials: RL
authors.lastname: Hooper
authors.affiliation: Centre for Primary Care and Public Health, Blizard Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, UK.
authors.forename: Mital
authors.initials: M
authors.lastname: Patel
authors.affiliation: Centre for Primary Care and Public Health, Blizard Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, UK.
authors.forename: Natasha
authors.initials: N
authors.lastname: Stevens
authors.affiliation: Centre for Primary Care and Public Health, Blizard Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, UK.
authors.forename: Zinat
authors.initials: Z
authors.lastname: Enayat
authors.affiliation: Centre for Primary Care and Public Health, Blizard Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, UK.
authors.forename: Zuhur
authors.initials: Z
authors.lastname: Balayah
authors.affiliation: Centre for Primary Care and Public Health, Blizard Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, UK.
authors.forename: Asmat
authors.initials: A
authors.lastname: Syed
authors.affiliation: Centre for Primary Care and Public Health, Blizard Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, UK Advanced Medical and Dental Institute, Universiti Sains Malaysia, Penang, Malaysia.
authors.forename: Aishah
authors.initials: A
authors.lastname: Knight
authors.affiliation: Centre for Primary Care and Public Health, Blizard Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, UK.
authors.forename: David A
authors.initials: DA
authors.lastname: Jolliffe
authors.affiliation: Centre for Primary Care and Public Health, Blizard Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, UK.
authors.forename: Claire L
authors.initials: CL
authors.lastname: Greiller
authors.affiliation: Centre for Primary Care and Public Health, Blizard Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, UK.
authors.forename: David
authors.initials: D
authors.lastname: McLaughlin
authors.affiliation: Homerton University Hospital, London, UK.
authors.forename: Timothy R
authors.initials: TR
authors.lastname: Venton
authors.affiliation: Homerton University Hospital, London, UK.
authors.forename: Marion
authors.initials: M
authors.lastname: Rowe
authors.affiliation: Homerton University Hospital, London, UK.
authors.forename: Peter M
authors.initials: PM
authors.lastname: Timms
authors.affiliation: Royal London Hospital, London, UK.
authors.forename: Duncan
authors.initials: D
authors.lastname: Clark
authors.affiliation: London School of Hygiene and Tropical Medicine, London, UK.
authors.forename: Zia
authors.initials: Z
authors.lastname: Sadique
authors.affiliation: Centre for Primary Care and Public Health, Blizard Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, UK.
authors.forename: Sandra M
authors.initials: SM
authors.lastname: Eldridge
authors.affiliation: Centre for Primary Care and Public Health, Blizard Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, UK.
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Griffiths
mesh_terms: D000208:Acute Disease; D000368:Aged; D017028:Caregivers; D002762:Cholecalciferol / Q000627:therapeutic use*; D019587:Dietary Supplements; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D004334:Drug Administration Schedule; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009735:Nursing Homes; D012141:Respiratory Tract Infections / Q000517:prevention & control*; D014815:Vitamins / Q000627:therapeutic use*
chemical_list: D014815:Vitamins; D002762:Cholecalciferol
keywords: Respiratory Infection