Effect of vitamin K on improving post‑kidney transplant outcomes: a meta‑analysis

The effect of vitamin K on clinical outcomes in patients receiving kidney transplantation is contested according to previous studies. This meta-analysis aimed to summarize the impact of vitamin K on all-cause mortality, renal function, inflammation, and vascular/bone health in patients receiving kidney transplantation. EMBASE, PubMed, and Cochrane were searched for literature concerning the effect of vitamin K on clinical outcomes of patients receiving kidney transplantation until December 2022. Normal vitamin K status/vitamin K supplementation was considered as the experimental group; while vitamin K deficiency/no vitamin K supplementation was considered as the control group. All-cause mortality, renal function indexes, C-reactive protein (CRP), and vascular/bone health indexes were extracted and analyzed. A total of seven studies with 1,101 patients in the experimental group and 651 patients in the control group were included. All-cause mortality was decreased in the experimental group vs. the control group [relative risk (95% confidence interval (CI)]: 0.72 (0.60-0.86), P<0.001]. Regarding renal function indexes, the estimated glomerular filtration rate was increased in the experimental group vs. the control group [mean difference (95% CI): 9.87 (1.48-18.26), P=0.021]; while creatinine and albumin remained unchanged between the two groups (both P>0.05). Moreover, CRP, systolic blood pressure, diastolic blood pressure, triglycerides, hemoglobin, calcium, and 25-hydroxyvitamin D were unchanged between the two groups (all P>0.05). Publication bias was low, and the robustness assessed by sensitivity analysis was generally acceptable. Thus vitamin K exerted a potential implication in reducing all-cause mortality and improving renal function in patients receiving kidney transplantation.