Association between red cell distribution width and mortality in patients undergoing continuous ambulatory peritoneal dialysis

Objective To investigate the association of red cell distribution width (RDW) with all-cause and cardiovascular disease (CVD)-related mortality in patients undergoing continuous ambulatory peritoneal dialysis (CAPD). Methods A retrospective analysis was performed on 207 patients who initiated CAPD for more than 3 months between July 2005 and March 2016 in the First Hospital Affiliated to Zhengzhou University. Baseline data on demographic, clinical and biochemical variables as well as comorbidities were obtained; medications and clinic outcomes were recorded. According to receiver operator characteristic curve (ROC) analysis, patients were divided into high RDW (RDW＞15.1%) and low RDW (RDW≤15.1%) groups. The data of two groups were compared and Spearman's correlation analysis was used to explore the association of RDW with clinical and biochemical parameters. Survival curves were calculated using Kaplan-Meier method. Cox regression model was employed to analyze risk factors of all-cause and CVD-related mortality. Results In this study, 207 CAPD patients were enrolled. The overall median survival time was 80 months. And the median survival time of high RDW group (68 patients) and low RDW group (139 patients) were 59 months and 96 months, respectively. There were statistical differences in diastole pressure, hemoglobin, hematocrit, serum albumin, intact parathyroid hormone (iPTH), eGFR, cholesterol, lipoprotein a, 4-hour dialysate-to-plasma ratio for creatinine (4hD/Pcr), total Ccr (P＜0.05, respectively); the two groups also varied in the proportion of chronic obstructive pulmonary disease, cardiovascular disease and hyperlipidemia, as well as in the use of iron supplements, angiotensin-converting enzyme (ACE) inhibitors or angiotensin Ⅱ receptor blockers (ARB), and beta-receptor blockers (P＜0.05, respectively). Cardiovascular event was a leading cause of mortality. Kaplan-Meier survival curves showed that the high RDW group had higher all-cause and CVD-related mortality compared with the low RDW group (P＜0.01). The 1-year, 3-year, and 5-year patient survivals of the high RDW and low RDW group were 87.97% vs 97.01%, 58.02% vs 81.53%, and 41.62% vs 67.96%, respectively, demonstrating significant differences (P=0.001). Multivariate Cox regression analysis showed that high RDW was independent risk factor for all-cause mortality (HR=1.212, 95%CI: 1.007-1.458, P=0.042) and CVD-related mortality (HR=1.697, 95%CI:1.030-2.795, P=0.038). Conclusion RDW is associated with mortality risks in CAPD patients and can be stratified as a valuable indicator for the risk of death.