title: A phase IV, two-armed, randomized, cross-over study comparing compliance with once-a-month administration of vitamin D3 to compliance with daily administration of a fixed-dose combination of vitamin D3 and calcium during two 6-month periods.
abstract: In a randomized, cross-over study, once monthly administration of vitamin D3 was preferred over a once daily administration of a fixed-dose combination of vitamin D3 and calcium, with a better compliance but without any significant difference in the increase in vitamin D levels.
  
  
  BACKGROUND
  The aim of the present study was to compare a once-monthly administration of vitamin D3 to a daily administration of a fixed-dose combination of vitamin D3 and calcium during two treatment periods of 6 months.
  
  
  METHODS
  One hundred volunteers aged 50 years old or older were randomized to receive either one drinkable ampoule containing 25,000 IU vitamin D3 (D-Cure®, SMB) once monthly (group VD) or one chewable tablet containing 1000 mg calcium carbonate + 800 IU vitamin D3 (Steovit Forte®, Takeda) once daily (group VDCa) during 6 months. After the first 6 months of treatment, the groups were reversed according to the randomized cross-over design. Treatment compliance (i.e. the primary outcome), preference, acceptability and vitamin D levels and adverse events were all collected.
  
  
  RESULTS
  For the two periods, the patients had a significantly higher compliance in the VD group than in the VDCa group (p < 0.0001). During the study, 50 (56.8 %) patients preferred the VD treatment, 16 (18.2 %) patients preferred the VDCa, and for 22 (25.0 %) patients, neither treatment was preferred. At the end of the first 6 months of treatment, the mean (SD) increase of 25(OH)D was 6.57 ng/mL (8.19) in the VD group and 3.88 ng/mL (10.0) in the VDCa group (p = 0.16 between groups).
  
  
  CONCLUSIONS
  In this study, a once-monthly administration of vitamin D3 was preferred over a once-daily administration of a fixed-dose combination of vitamin D3 and calcium, with a better compliance but without any significant difference in the increase in vitamin D levels.
authors.affiliation: Support Unit in Epidemiology and Biostatistics, Department of Public Health, Epidemiology and Health Economics, University of Liège, Liège, 4000, Belgium. olivier.bruyere@ulg.ac.be.
authors.forename: O
authors.initials: O
authors.lastname: Bruyère
authors.affiliation: Médecine Appareil Locomoteur, CHU Liège, BRULL, Liège, Belgium.
authors.forename: R
authors.initials: R
authors.lastname: Deroisy
authors.affiliation: Support Unit in Epidemiology and Biostatistics, Department of Public Health, Epidemiology and Health Economics, University of Liège, Liège, 4000, Belgium.
authors.forename: N
authors.initials: N
authors.lastname: Dardenne
authors.affiliation: Department of Clinical Chemistry, University of Liège, Liège, Belgium.
authors.forename: E
authors.initials: E
authors.lastname: Cavalier
authors.affiliation: SMB Belgium, Brussels, Belgium.
authors.forename: M
authors.initials: M
authors.lastname: Coffiner
authors.affiliation: SMB Belgium, Brussels, Belgium.
authors.forename: S
authors.initials: S
authors.lastname: Da Silva
authors.affiliation: SMB Belgium, Brussels, Belgium.
authors.forename: S
authors.initials: S
authors.lastname: De Niet
authors.affiliation: Support Unit in Epidemiology and Biostatistics, Department of Public Health, Epidemiology and Health Economics, University of Liège, Liège, 4000, Belgium.
authors.forename: J-Y
authors.initials: JY
authors.lastname: Reginster
mesh_terms: D000368:Aged; D002118:Calcium / Q000008:administration & dosage* / Q000009:adverse effects / Q000627:therapeutic use; D002762:Cholecalciferol / Q000008:administration & dosage* / Q000009:adverse effects / Q000627:therapeutic use; D018592:Cross-Over Studies; D004334:Drug Administration Schedule; D004338:Drug Combinations; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010024:Osteoporosis / Q000188:drug therapy*; D016903:Drug Monitoring
chemical_list: D004338:Drug Combinations; D002762:Cholecalciferol; D002118:Calcium
keywords: 25OHD; Compliance; Preference; Randomized controlled trial; Vitamin D