Krieg 1999.

Methods	Randomised clinical trial using parallel group design (two intervention groups).
Participants	Country: Switzerland. Number of participants randomised: 248 elderly institutionalised women 62 to 98 (mean 84.5) years of age. Inclusion criteria: elderly institutionalised women. Exclusion criteria: not reported.
Interventions	Participants were randomly assigned to receive: Intervention group 1: vitamin D3 (880 IU) plus calcium (1000 mg) daily (n = 124); Intervention group 2 (Control group): no treatment (n = 124); for a two‐year period.
Outcomes	The primary outcomes were quantitative ultrasound parameters of bones and metabolic disturbances.
Stated aim of study	"To assess the effect of supplementation with vitamin D and calcium on quantitative ultrasound parameters and metabolic disturbances in elderly institutionalised women."
Notes	"The drugs were given by the nursing staff to avoid lack of compliance." Trial agents were provided by Novartis Pharma, Basle, Switzerland.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	The trial is described as randomised but the method of sequence generation was not specified.
Allocation concealment (selection bias)	High risk	The allocation sequence was known to the investigators who assigned participants.
Blinding (performance bias and detection bias) All outcomes	High risk	Trial was not blinded, so that the allocation was known during the trial. Placebo was not used.
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	Trial agents were provided by Novartis Pharma, Basle, Switzerland.
Other bias	Low risk	The trial appears to be free of other components that could put it at risk of bias.