Sanders 2010.

Methods	Single centre, randomised, double‐blind, placebo‐controlled trial using parallel group design (two intervention groups). The Vital D study.
Participants	Country: Australia. Number of participants randomised: 2258 community‐dwelling women, 70 years or older (mean age 76 years) considered to be at high risk of fracture. Inclusion criteria: community‐dwelling women at higher risk of hip fracture, defined by criteria such as maternal hip fracture, past fracture, or self‐reported faller. Exclusion criteria: unable to provide informed consent or information about falls or fractures; permanently resided at a high‐level care facility; had an albumin‐corrected calcium level higher than 2.65 mmol/L; or had a creatinine level higher than 150 μmol/L, or currently took vitamin D doses of 400 IU or more, calcitriol, or antifracture therapy.
Interventions	Participants were randomly assigned to receive: Intervention group 1: vitamin D3 500,000 IU yearly (n = 1131); Intervention group 2 (Control group): matched placebo tablet of vitamin D yearly (n = 1127); for a three to five years (in autumn or winter), median 2.96 years. "Ten tablets were mailed to participants annually (March‐August, determined by recruitment date) with instructions to take all tablets on a single day. Study staff confirmed by telephone the ingestion of study medication within 2 weeks. Subsequent dosing occurred within 2 weeks of the anniversary of the first dose."
Outcomes	The primary outcome measures were falls and fractures. Secondary outcome measures were serum 25‐hydroxycholecalciferol and intact parathyroid hormone levels.
Stated aim of study	"To determine whether a single annual dose of 500 000 IU of cholecalciferol administered orally to older women in autumn or winter would improve adherence and reduce the risk of falls and fracture."
Notes	"Study staff confirmed by telephone the ingestion of study medication." Study medication was supplied by PSM Healthcare, Auckland, New Zealand.
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 performed by an independent statistician. Treatment allocation status was e‐mailed directly to the hospital clinical trials pharmacist responsible for dispensing study medication."
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. The participants and study staff were blinded to intervention group.
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	Study medication was supplied by PSM Healthcare, Auckland, New Zealand.
Other bias	Low risk	The trial appears to be free of other components that could put it at risk of bias.