Abstract: 【Abstract】Objective To explore the relationship between the values of baseline red blood cell distribution width (RDW), time-averaged RDW and RDW dynamic trends and the all-cause mortality in continuous ambulatory peritoneal dialysis (CAPD) patients. Methods We reviewed 89 incident patients undergoing (CAPD) between July 1, 2005 and June 30, 2017 treated at the Peritoneal Dialysis Center of Beijing Hospital and examined the changes of RDW from baseline to December 31, 2018. We then assessed the relationship between the values of baseline RDW and time-averaged RDW and the risk of mortality. The optimal cut-off value of time- averaged RDW was determined based on receiver operating characteristic (ROC) curve. We assigned the patients into four groups according to baseline RDW and time-averaged RDW: "double-low" RDW group at baseline and follow-up; low baseline and high follow-up RDW group; high baseline and low followup RDW group; and "double-high" RDW group at baseline and follow-up. The difference of prognosis was observed among the four groups. Results This study included 89 patients, with an average age of 62.6 years and a mean follow-up duration of 48.0 (32.0～66.0) months. Thirty-three patients (37.1%) died in the followup period. Baseline RDW and time-averaged RDW correlated positively with mortality (r=0.365, P＜0.001;r=0.520, P＜0.001). Multivariate COX regression analysis showed that time-averaged RDW was a significant predictor of all-cause mortality in the CAPD patients (HR=1.833, 95% CI: 1.158～2.899, P=0.010). The area under the curve (AUC) in ROC for time-averaged RDW was 0.881 (95％ CI: 0.686～0.808, P＜0.001), and the optimal prediction cut-off value was 14.1%. Compared with the "double-low" RDW group at baseline and follow-up, the cumulative survival rate was lower in the "double-high" RDW group and low baseline and high follow-up RDW group (c2=17.172, P＜0.001; c2=11.232,P=0.001). Conclusions Higher time-averaged RDW was associated with a higher risk of mortality among CAPD patients. Compared with the patients with persistently low RDW, those with persistently high RDW or low baseline and high follow-up RDW had poorer survival outcomes.

Key words: Peritoneal dialysis, Mortality, Red cell distribution width