Association Between Red Cell Distribution Width And Mortality In Patients Undergoing Continuous Ambulatory Peritoneal Dialysis

BackgroundWith an annual increasing number of patients in end-stage renal disease(ESRD)currently,the therapy of chronic kidney diseases has become one of the globally public health problems that need to be solved urgently.Comparing with hemadialysis and renal transplantation,peritoneal dialysis has many more advantages.For example,PD has very little influence on hemodynamics of patients and lower cross infection rate,costs less and can protect residual renal function better.Although peritoneal dialysis modes have been improved significantly over the past few decades,the mortality of PD patients remains high.The mortality of dialysis patients is 6.1 to 16 times higher than that of the general population.Cardiovascular disease(CVD)is the leading cause of death in patients with maintenance dialysis,accounting for 44% to 51% of all-cause mortality of CKD patients.Foreign investigation reveals that the cardiovascular disease mortality in dialysis patients is 10 to 20 times higher than that in the general population.Therefore,identifying and stratifying the risk of all-cause and CVD-related death in peritoneal dialysis patients is an important challenge in clinics and also can help clinicians to provide individualized treatment plan for patients.For dialysis patients,there is no widely used tool on predicting all-cause death and CVD death.Study on this issue is also limited.So finding a marker predicting all-cause and CVD mortality of patients undergoing continuous ambulatory peritoneal dialysis is of great significance.ObjectiveRDW is now confirmed to be associated with adverse outcomes in cardiovascular and other diseases.But evidence predicting mortality of peritoneal dialysis patients is still limited.This study reviewed the data of patients undergoing continuous ambulatory peritoneal dialysis at the first affiliated hospital of Zhengzhou university to investigate the association between RDW and the risk of both all-cause and CVD-related mortality of CAPD patients.Methods1.We recruited 403 incident CAPD patients between 1 July 2005 and 30 June 2016 from the first affiliated hospital of Zhengzhou university.Exclusion criterias include that(1)patients who were less than 18 years old(2)peritoneal dialysis vintage is less than 3 months(3)transfered to other dialysis center or lost to follow-up(4)did not detect RDW in the first 3 months of dialysis.(5)have not accomplished PET test and evaluated the adequacy of dialysis.All the patients performed the peritoneal dialysis catheterization in our hospital and used Baxter’s lactate dialysis fluid for dialysis.2.In this retrospective cohort study,all the patients were followed up from initation of dialysis vintage to death;or switching to hemodialysis or renal transplantation;or until 30 June 2016.We collected demographic and baseline clinical data of patients which included laboratory biochemical indicators,such as electrolytes,albumin,intact parathyroid hormone,renal function,and blood lipids,anemia related indicators such as RDW,hemoglobin,serum iron,ferritin,total iron binding capacity;dialysis related parameters within the first 3 months of dialysis.We reviewed medication used such as iron and erythropoietin.The comorbidities included cardiovascular disease,diabetes,hypertension,chronic obstructive pulmonary disease,PD related peritonitis and so on.Survival time,clinical outcomes and other information was also recorded.3.According to ROC analysis,the best cut-off value of RDW was determined by which subjects were divided into high RDW group and low RDW group.Differences between demographic and baseline clinical data of the two groups were compared.The correlation between the study factors and RDW was analyzed.Differences in survival of the two groups were assessed using Kaplan-Meier methods.Cox regression model was used to evaluate the association between RDW and clinical outcomes(all-cause and CVD-related mortality)of the patients.The predictive value of RDW and other traditional parameters of mortality of CAPD patients were evaluated by ROC analysis.Results1.The study cohort finally included 207 patients undergoing CAPD,among them there were 120 male patients(58%).The mean age was 45.2±13.2 years,the median age of dialysis vintage was 29.5 months(3-117).The leading causes of ESRD were chronic glomerulonephritis(142,68.6%),hypertension(27,13.0%),diabetes(15,7.2%),polycystic kidney(14,6.8%),other diseases(9,4.4%).2.The area under the curve in receiver operating characteristic analysis was 0.751(95% CI= 0.686-0.808,p<0.0001).Taking RDW15.1% as the optimal cut-off value,the patients were divided into high RDW group(RDW>15.1%,68 patients),the low RDW group(RDW≤15.1%,139 patients).There were statistically significant differences in the levels of diastolic blood pressure,hemoglobin,albumin,intact parathyroid hormone,eGFR,total cholesterol,lipoprotein a,total Ccr,and 4h D/Pcr.The proportion of cardiovascular disease,COPD,hyperlipidemia in the low RDW group was lower than that in high RDW group.Comparing with high RDW group,low RDW group has a higher proportion of iron supplement,ACEI/ARB and beta blockers used.3.Spearman correlation analysis showed that RDW was positively related to C-reactive protein,ferritin,Lipoprotein a,the comorbidity of cardiovascular disease,negatively related to hemoglobin,albumin,eGFR,total Ccr and the use of iron supplement and had no statistically significant association with age,dialysis age,total iron binding capacity,total cholesterol,total Kt/V,EPO,the comorbidity of hypertension and diabetes mellitus.4.Until 30 June 2016,53 people of 207 patients died,among them 20 patients died of cardiovascular events,12 patients died of infection,1 patients died of hepatic encephalopathy,and 20 patients died of other causes.According to T test,there were statistically difference in all-cause and CVD-related mortality between the two group,P<0.001.Kaplan-meier survival curves showed that the survival rate of low RDW group patients was significantly higher than that of high RDW group patients.5.The 1-year,3-year,5-year patient survival of high RDW and low RDW group were 87.97% vs 97.01%,58.02% vs 81.53%,41.62% vs 67.96%,respectively.The fully adjusted model of multivariate Cox regression analysis showed that RDW was risk factors for all-cause and CVD-related mortality.Conclusion1.As a hematological parameter reflecting erythrocyte volume heterogeneity,RDW is correlated with various variables of PD patients.2.RDW was associated with all-cause and CVD-related mortality of CAPD patients.RDW can be used as a predictor of mortality in CAPD patients and its predictive value is superior to other traditional indicators.