Bjorkman 2007.

Methods	Randomised, double‐blind, placebo‐controlled trial using parallel group design (three intervention groups).
Participants	Country: Finland. Number of participants randomised: 218 chronically bedridden patients (81.7 % women), 65 to 104 (mean 84.5) years of age. Inclusion criteria: age over 65 years, chronically impaired mobility, stable general condition, and no known present disease (except osteoporosis) or medication (vitamin D supplements, glucocorticoids, antiepileptics, etc.) affecting calcium or bone metabolism. Exclusion criteria: markedly elevated creatinine levels (> 125 µmol/L) hypercalcaemia (ionised calcium > 1.32 mmol/L), hypothyroidism (thyrotropin > 5.3 mU/L) or hyperthyroidism (thyrotropin < 0.2 mU/L).
Interventions	Participants were randomly assigned to receive: Intervention group 1: vitamin D3 (1200 IU) daily, (n = 73); 17 participants from this group received calcium 500 mg daily; Intervention group 2: vitamin D3 (400 IU) daily, (n = 77); 11 participants from this group received calcium 500 mg daily; Intervention group 3 (Control group): matched placebo vitamin D3 (0 IU) daily (n = 68), 15 participants from this group received calcium 500 mg daily; for a six‐month period. "Participants received vitamin D3 (Vigantol, Merck KGaA, Darmstadt, Germany 20,000 IU/ml in Migliol oil) in doses of 0 µg, 140 µg, or 420 µg (groups 1, 2, 3) every 2 weeks, equivalent with average daily intakes of 0 IU, 400 IU, or 1200 IU. To ensure that all three groups received identical volumes (26 drops = 0.84 ml), medication oil was diluted three‐fold with Migliol oil in group 2, and group 1 received plain Migliol oil. Furthermore, the oil was swallowed entirely in the presence of the nurse and given with a small amount of food or drink, if necessary." "Before the start of the intervention, the use of dairy products was roughly evaluated to be insufficient among 40 patients, who received a daily calcium carbonate substitution of 500 mg during the intervention. Three other patients also received a previous daily medication of 500 mg calcium carbonate at entry, which they continued to receive through the intervention."
Outcomes	The primary outcome measures were parathyroid function and bone turnover.
Stated aim of study	"To evaluate the effects of vitamin D supplementation on parathyroid function and bone turnover in aged, chronically immobile patients."
Notes	"Vitamin D supplementation was well tolerated. One patient, however, developed a mild hypercalcaemia (ionised calcium from 1.24 to 1.40 mmol/L) in group 3." Treatment agents were produced by Vigantol, Merck KGaA, Darmstadt, Germany. Authors did not provide data about compliance. Additional information on the risk of bias domains was received through personal communication with Dr Mikko Björkman (31.01.2009).
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Sequence generation was achieved using computer random number generation.
Allocation concealment (selection bias)	Low risk	"Allocation was controlled by coded bottles. Each bottle was individually coded to blind the participants and the ward nurses of not only the content of the bottles but also of the group labels (1, 2, 3)."
Blinding (performance bias and detection bias) All outcomes	Low risk	The trial was described as blinded, the parties that were blinded, and the method of blinding was described, so that knowledge of allocation was adequately prevented during the trial.
Incomplete outcome data (attrition bias) All outcomes	Low risk	The numbers and reasons for dropouts and withdrawals in all intervention groups were described.
Selective reporting (reporting bias)	Low risk	Pre‐defined, or clinically relevant and reasonably expected outcomes are reported on.
Industry bias	Unclear risk	Treatment agents were produced by Vigantol, Merck KGaA, Darmstadt, Germany.
Other bias	Low risk	The trial appears to be free of other components that could put it at risk of bias.