Vitamin D Therapy in Adults With CKD: A Systematic Review and Meta-analysis

Area of Science:

• Nephrology
• Endocrinology
• Cardiovascular Medicine
• Bone Metabolism

Background:

• Chronic kidney disease (CKD) increases mortality risk, cardiovascular disease, and fractures, often linked to CKD-mineral and bone disorder (CKD-MBD).
• CKD-MBD involves altered bone and mineral metabolism, leading to vascular calcification and poor bone quality.
• Vitamin D is a common treatment for CKD-MBD, necessitating an evaluation of its clinical impact.

Purpose of the Study:

• To evaluate the effects of vitamin D therapy on mortality, cardiovascular, bone, and kidney outcomes in adults with CKD.
• To synthesize evidence from randomized controlled trials (RCTs) regarding vitamin D's efficacy and safety in CKD management.

Main Methods:

• Systematic review and meta-analysis of 128 RCTs involving 11,270 participants with stage 3-5 CKD (excluding kidney transplant recipients).
• Searched MEDLINE, Embase, and CENTRAL databases up to February 25, 2023; included RCTs with ≥3 months follow-up.
• Assessed risk of bias using Cochrane RoB 2 tool and evidence certainty using GRADE; primary endpoints included all-cause death, cardiovascular death, and fracture.

Main Results:

• Vitamin D therapy likely had no significant effect on all-cause death (RR, 1.04; 95% CI, 0.84-1.24) compared to placebo.
• Effects on fracture (RR, 0.68; 95% CI, 0.37-1.23) and cardiovascular death (RR, 0.73; 95% CI, 0.31-1.71) were uncertain.
• Vitamin D therapy lowered serum parathyroid hormone and alkaline phosphatase but increased serum calcium levels.

Conclusions:

• Vitamin D therapy did not reduce the risk of all-cause death in individuals with CKD.
• The effects of vitamin D on fracture, cardiovascular, and kidney outcomes in CKD patients remain uncertain.
• Limitations include short follow-up periods, small sample sizes, and suboptimal trial quality in the included studies.