Vitamin D supplementation is not associated with a decreased risk of falls, meta-analysis finds

Vitamin D supplementation with or without calcium does not reduce falls by a significant amount, according to a new meta-analysis.

Researchers performed a trial-sequential meta-analysis to examine whether additional randomized, controlled trials of vitamin D's effect on falls were necessary. A trial-sequential analysis is a cumulative meta-analysis that maintains an overall risk of 5% for type 1 error, the researchers noted, thereby reducing the risk for false-positive results caused by repetitive statistical testing. The analysis included all participants who fell in an intention-to-treat analysis. The study results were published online April 24 by Lancet Diabetes & Endocrinology.

Twenty randomized, controlled trials involving 29,535 patients were included in the meta-analysis. Seventeen of the trials were double-blind and placebo-controlled. The researchers performed a traditional meta-analysis and found that a pooled analysis showed no effect of vitamin D, with or without calcium, on fall risk. In the trial-sequential analysis, the effect estimate of vitamin D with or without calcium was within the futility boundary, indicating that it did not reduce the relative risk by 15% or more. The authors also performed a sensitivity analysis with a risk reduction threshold of 10% and a subgroup analysis of vitamin D and vitamin D with calcium with a risk reduction threshold of 15%; the effect estimate remained within the futility boundary in both analyses.

The authors noted that the included trials had high statistical heterogeneity between results and that the trial-sequential design assumes that results of future trials will be similar to those of existing trials. However, they concluded that fall risk does not decrease by 15% or more as a result of supplementation with vitamin D, with or without calcium. “Further clinical trials of the effect of vitamin D supplements on falls might be difficult to justify,” the authors wrote. “At present, there is little justification for prescribing vitamin D supplements to prevent falls.”

The authors of an accompanying comment said that the current study “contributes to the ongoing controversy concerning interventions to reduce falls in older people.” They noted that the study's results question whether small, underpowered randomized trials can show an effect of vitamin D supplementation on falls and said that the feasibility of a large trial has yet to be established. “Until then, we are left with uncertainty about the benefits of vitamin D supplementation for reduction in fall risk, particularly among vulnerable older people,” the comment authors wrote.