In this meta-analysis, we evaluated the association between serum 25-hydroxyvitamin D (25(OH) vitamin D) level and the risk of total fractures and hip fractures. Low serum 25(OH) vitamin D level is associated with an increased risk of total and hip fractures.
Introduction: Data on the association between serum 25(OH) vitamin D level and the risk of fractures are conflicting. This study aimed to provide a summary of prospective cohort or nested case-control studies on the association between serum 25(OH) vitamin D level and the risk of total fractures and hip fractures.
Methods: We identified relevant studies by searching the PubMed, EMBASE, and OVID databases from their inception to June 1, 2016. We included published prospective cohort or nested case-control studies evaluating the associations of serum 25(OH) vitamin D level with the fracture risk. Two reviewers abstracted the data independently. Relative risks (RRs) with 95% confidence intervals (CIs) were derived throughout the whole analysis.
Results: Sixteen prospective cohort studies and three nested case-control studies were included. We found that low serum 25(OH) vitamin D level was significantly associated with the risk of total fractures (RR 1.25, 95% CI 1.06-1.43; I 2 = 31.3%, p for heterogeneity = 0.15) and hip fractures (RR 1.48, 95% CI 1.29-1.68; I 2 = 0%, p for heterogeneity = 0.51). The hip fracture risk was increased by 40% for each SD decrease in serum 25(OH) vitamin D level (RR 1.40, 95% CI 1.20-1.61; I 2 = 0%, p for heterogeneity = 0.51). The per SD decrease in serum 25(OH) vitamin D level was not associated with the increased risk of total fractures (RR 1.14, 95% CI 0.93-1.35; I 2 = 63.2%, p for heterogeneity = 0.04).
Conclusions: Our study suggests that low serum 25(OH) vitamin D level is associated with increased risks of total and hip fractures. In the analyzed studies, the per SD decrease in serum 25(OH) vitamin D level was associated with the hip fracture risk but not with the total fracture risk.
Keywords: Cohort; Fracture; Meta-analysis; Serum 25(OH) vitamin D.