Associations of vitamin K status with mortality and cardiovascular events in peritoneal dialysis patients.

Purpose: Vitamin K deficiency, expressed by a high level of desphospho-uncarboxylated matrix GLA protein (dp-ucMGP), is highly prevalent in dialysis patients. However, the predictive ability of the vitamin K status remains unclear in continuous ambulatory peritoneal dialysis (CAPD) patients.
Methods: 158 prevalent CAPD patients with a median level of dp-ucMGP of 1093 (752, 1485) pmol/L were enrolled. Patient outcomes including all-cause mortality and cardiovascular events (CVEs) were recorded during follow-up. Survival curves were performed using Kaplan-Meier method, and the influences of dp-ucMGP on outcomes were analyzed by Cox regression models.
Results: A total of 59 deaths and 82 new episodes of CVEs occurred during median follow-up of 31.4 ± 13.1 months (range: 3.8-48.0 months). Kaplan-Meier analysis revealed patients with higher dp-ucMGP levels (≥ 1093 pmol/L) had an increased risk for both mortality (P = 0.005) and CVEs (P < 0.001). Multivariable Cox regression confirmed that higher dp-ucMGP levels increase the mortality risk [hazard ratio (HR), 1.763; 95% CI 1.045-3.291] and CVEs (HR, 1.846; 95% CI 1.074-3.172). For every 100 pmol/L increase in serum dp-ucMGP, the adjusted HRs for mortality and CVEs were 1.054 (95% CI 1.008-1.106) and 1.034 (95% CI 1.012-1.089), respectively.
Conclusions: Vitamin K deficiency, as expressed by high dp-ucMGP levels, showed independently associations with mortality and CVEs in CAPD patients.