Vitamin D supplementation and falls: a trial sequential meta-analysis.
BACKGROUND
Vitamin D supplementation is often recommended to prevent falls, although vitamin D trials and meta-analyses of these trials have reported conflicting results for this outcome. We aimed to assess if there was a need for further research.


METHODS
We explored the value of doing further randomised controlled trials assessing the effects of vitamin D supplements on falls with trial sequential analysis with a risk reduction threshold of 15%. All analyses were done using the numbers of participants who had a fall in intention-to-treat analyses. Trial sequential analysis performs a cumulative meta-analysis, but reduces the risk of false-positive results from repetitive statistical testing by maintaining the overall risk of type 1 error at 5%.


RESULTS
In 20 existing randomised controlled trials (n=29,535), the effect estimate for vitamin D with or without calcium on falls lay within the futility boundary, providing evidence that vitamin D supplementation does not alter the relative risk by 15% or more. In a sensitivity analysis using a risk reduction threshold of 10%, the effect estimate also lay within the futility boundary. In subgroup analyses using a risk reduction threshold of 15%, the effect estimate also lay within the futility boundary for trials of vitamin D supplementation (16 trials, n=22,291) and trials of vitamin D with calcium (six trials, n=9919).


CONCLUSIONS
In pooled analyses, supplementation with vitamin D, with or without calcium, does not reduce falls by 15% or more. Future trials with similar designs are unlikely to alter these conclusions. At present, there is little justification for prescribing vitamin D supplements to prevent falls.


BACKGROUND
Health Research Council of New Zealand.
Department of Medicine, University of Auckland, Auckland, New Zealand. Electronic address: m.bolland@auckland.ac.nz.
Mark J
MJ
Bolland
Department of Medicine, University of Auckland, Auckland, New Zealand.
Andrew
A
Grey
Department of Medicine, University of Auckland, Auckland, New Zealand.
Greg D
GD
Gamble
Department of Medicine, University of Auckland, Auckland, New Zealand.
Ian R
IR
Reid
D000058:Accidental Falls / Q000517:prevention & control*; D000368:Aged; D000369:Aged, 80 and over; D002136:Calcium, Dietary / Q000627:therapeutic use; D019587:Dietary Supplements; D005260:Female; D006801:Humans; D008297:Male; D016032:Randomized Controlled Trials as Topic; D014807:Vitamin D / Q000627:therapeutic use*
D002136:Calcium, Dietary; D014807:Vitamin D