Level 1: Likely reliable evidence
A number of systematic reviews and randomized trials have found evidence that vitamin D prevents falls and fractures in the elderly (JAMA. 2004;291:1999-2006), but adherence to daily supplements can be problematic for older patients. One way to address this problem might be to give vitamin D less often and use a higher dose. A large randomized trial evaluated the efficacy of a single annual high-dose vitamin D3 (cholecalciferol) supplement with 2,256 community-dwelling women in Australia (JAMA. 2010;303:1815-1822). Women aged 70 years and older who were at high risk for fractures were randomized to a single annual oral dose of vitamin D3 500,000 units vs. placebo. They participated for three to five years and were followed for one year after their last dose. The vitamin D3 group experienced a higher rate of falls (83.4 vs. 72.7 per 100 person-years, P=0.03) and an increase in radiologically confirmed fractures (4.9 vs. 3.9 per 100 person-years, P=0.047). The risk of falls remained significantly higher for the vitamin D3 group after adjustment for baseline calcium intake.