Clinical summary

###Background Trials give conflicting results for the role of vitamin D supplementation and rate of fractures.

###Methods Trials were identified via existing meta-analyses and additional searches of MEDLINE and CENTRAL. Plots was made using openMetaAnalysis. openMetaAnalysis uses R programming language hosted online at openCPU and the R library meta.

###Results When all trials are pooled, there is no associate between vitamin D supplementation and rate of fractures (plot). Meta-regression show that fracture reduction is associated with both the change in vitamin D levels (plot) and the final achieved achieved (plot). Subgroup analysis (Figure below) shows that trials that achieved effective supplementation of vitamin D, defined as a dose that raises the serum level of vitamin D by 20 nmol/L (8 ng/mL) and achieves a final level of at least 60 nmol/L (24 ng/mL). Additional subgrouping of the trials with effective dosing into those trials with and without calcium as a cotreatment show similar results but the trials without cotreatment do not quite reach statistical significance.(plot)

###Conclusion Vitamin D supplementation, when given in effective doses, is associated with reduced fractures. However, this observation should be tested in prospective trials with and without cotreatment with calcium.

##Details Full details of this review are published in ...