Serum 25-hydroxyvitamin D status and cardiovascular outcomes in chronic peritoneal dialysis patients: a 3-y prospective cohort study

Background: Patients with kidney disease are at high risk of developing 25-hydroxyvitamin D [25(OH)D] deficiency. Objective: We studied the association between serum 25(OH)D status and clinical outcomes of chronic peritoneal dialysis patients. Design: We measured serum 25(OH)D concentrations in 230 prevalent peritoneal dialysis patients and then followed these patients prospectively for 3 y or until death. Results: Serum 25(OH)D was deficient or insufficient (ie, <75nmol/L) in 87% of the patients. Adjusting for clinical and demographic factors, every 1-unit increase in log-transformed serum 25 (OH)D was associated with a 44% reduction in the hazard of fatal or nonfatal cardiovascular events (95% CI: 0.35, 0.91; P = 0.018). However, the association was gradually lost when additional adjustment was made in a stepwise fashion for residual glomerular filtration rate (P = 0.078) and echocardiographic measures (P = 0.39). Kaplan-Meier estimates showed a significantly greater fatal or nonfatal cardiovascular event-free survival probability among patients with serum 25(OH)D > 45.7 nmol/L (median) than among patients with concentrations <= 45.7 nmol/L (P = 0.004). In addition, patients with 25(OH)D > 45.7 nmol/L had a significantly higher cardiovascular event-free survival probability than did patients with 25(OH)D :5 45.7 nmol/L in the stratified analysis for patients with left ventricular mass index less than the median (P = 0.013) or normal systolic function (P = 0.005). Conclusions: A lower serum 25(OH)D concentration was associated with an increased risk of cardiovascular events in chronic peritoneal dialysis patients. Furthermore, serum 25(OH)D status appeared to show a differential influence on the cardiovascular outcomes of peritoneal dialysis patients depending on the degree of left ventricular hypertrophy and systolic dysfunction.