Vitamin D and calcium reduces the risk of hip and any fractures. - GreenMedInfo Summary
Vitamin D Supplementation and Fractures in Adults: A Systematic Umbrella Review of Meta-Analyses of Controlled Trials.
J Clin Endocrinol Metab. 2021 Oct 23. Epub 2021 Oct 23. PMID: 34687206
CONTEXT: The growing number of systematic reviews/meta-analyses (SR/MAs) on vitamin D (±calcium) for fracture prevention has led to contradictory guidelines. This umbrella review aims to assess the quality and explore the reasons for discrepancy of SR/MAs of trials on vitamin D supplementation for fracture risk reduction in adults.
EVIDENCE ACQUISITION: We searched 4 databases (2010-2020), Epistemonikos, and references of included SR/MAs, and we contacted experts in the field. We used AMSTAR-2 for quality assessment. We compared results and investigated reasons for discordance using matrices and sub-group analyses (PROSPERO registration: CRD42019129540).
EVIDENCE SYNTHESIS: We included 13 SR/MAs on vitamin D and calcium (Ca/D) and 19 SR/MAs on vitamin D alone, compared to placebo/control. Only 2 from 10 SR/MAs on Ca/D were of moderate quality. Ca/D reduced the risk of hip fractures in 8/12 SR/MAs (relative risk (RR) 0.61-0.84), and any fractures in 7/11 SR/MAs (RR 0.74-0.95). No risk reduction was noted in SR/MAs exclusively evaluating community-dwelling individuals or in those on vitamin D alone compared to placebo/control. Discordance in results between SR/MAs stems from inclusion of different trials, related to search periods and eligibility criteria, and varying methodology (using intention to treat, per-protocol, or complete case analysis from individual trials). Vitamin D alone has no protective effect on fracture risk.
CONCLUSIONS: Ca/D reduces the risk of hip and any fractures, possibly driven by findings from institutionalized subjects. Individual participant data meta-analyses of patients on Ca/D with sufficient follow-up period, and subgroup analyses, would unravel determinants for a beneficial response to supplementation.