Red Blood Distribution Width Predicts All-cause Mortality In Peritoneal Dialysis Patients

Objective:Red blood cell distribution width(RDW)is a measure of the heterogeneity in the size of erythrocytes,which is routinely included in the complete blood cell count.Recently,RDW has been found to be an independent predictor of all-cause mortality in heart failure,stroke and critically ill patients.The purpose of this study was to investigate whether RDW is associated with the mortality in peritoneal dialysis patients.Methods:1.Two hundred and seventy five patients received peritoneal dialysis from 2003-2016 were enrolled in the second affiliated hospital of Soochow University.Patients were consecutively recruited and followed up every two months in the following 13 years.Patients included received peritoneal dialysis for at least three months and were absent from microcytic anemia,infection,acute cardiac failure or myocardinal infarction within 3 weeks before the sample collecting.2.Enrollmented the demographic data,biochemistry data and the blood parameter such as Age,Co-morbidity,PD duration(mons),RRF,Total Kt/V,Hemoglobin(g/L),MCV(fl),Albumin(g/L),CH(mmol/L),TG(mmol/L),BUN(mmol/L)and so on.The normal range of RDW in our lab is 11%-15%.Primary outcome was the all-cause mortality and the cardiovascular mortality at the end of the follow-up.3.The value of RDW was categorized into four quartiles(Q1,≤13.4;Q2,13.4–14.2;Q3,14.2–15.1;Q4,≥15.1).Demographic factors were compared across RDW quartiles by using ANOVA for continuous variables,or chi-squared test for categorical variable.Survival curve was computed by Kaplan–Meier method.Cox proportional hazard analysis was performed by using RDW as a continuous variable.Calculations were performed using SPSS for Windows 17.0.1.Results:275 participants were included in this study,the median age of the population was 57.5±15.7 years,54.9% were male.The mean dialysis duration was 22.2±18 months.By using the backward stepwise multiple linear regression analysis,only age(0.012±0.006,P=0.044),PD duration(-0.025±0.005,P<0.001),RRF(-0.060±0.029,P=0.044),MCV(-0.031±0.012,P=0.012),Fe(-0.041±0.017,P=0.019)and albumin(-0.045±0.015,P=0.015)were associated with RDW.In the death group,the RDW(15.3±1.74 versus 13.9±1.24%,P<0.01)and log CRP(1.04±0.45 versus 0.73±0.24,P=0.01)were significantly higher,while albumin(25.3±5.6 versus 32.2±5.2,P<0.01),pre-albumin(233.4±129.3 versus 346.3±124.1,P<0.01),Hb(100.0± 21.6 versus 108.2±22.9,P<0.01),Scr(661.9±259.8 versus 776.7±324.5,P=0.03),UA(416.7±107.2 versus 449.8±106.7,P=0.02),RRF(2.95±1.9 versus 3.95±2.9,P=0.05)and RKt/V(0.44±0.34 versus 0.58±0.44,P=0.01)were significantly lower.The Kaplan–Meier crude analyses demonstrated that higher RDW quartile was associated with increased death.The multivariate analysis with the Cox risk model with the adjustment for age,hamemoglobin,MCV,albumin,pre-albumin,CR,UA,CRP,serum calcium,phosphorus levels and diabetes etc,which revealed that the fourth quartile RDW was strongly associated about the risk of death.In addition,a 1% increment of RDW was associated with 34% increased hazard of all-cause mortality.The AUC of the RDW values for mortality was 0.76(P<0.01).Conclusion:1.The association between RDW and age,PD duration,RRF,MCV,Fe,albumin are statistical significance.2.The patients are trending to occur a bad outcome when the RDW and log CRP were significantly higher,while albumin,pre-albumin,Hb,Scr,UA,RRF and RKt/V were significantly lower.3.RDW was associated with the hazard of all-cause mortality.Higher RDW level demonstrates a higher mortality risk.4.RDW is an independent predictor of all-cause mortality.