| BackgroundIn recent years,with the annual increasing prevalence and incidence of chronic kidney disease(CKD)and end-stage renal disease(ESRD),they have been recognized as the one of main public health burden in the world,so it is particularly important to find effective prevention and treatment methods for chronic kidney disease.Peritoneal dialysis(PD)and hemodialysis are options for ESRD patients who can’t undergo preemptive kidney transplantation.Compared with hemodialysis,peritoneal dialysis has become an essential renal replacement therapy for a number of ESRD patients due to advantages of learning at home easily,less cost,less impact on hemodynamics,lower risk of hospital-acquired infections,and better residual renal function protection.Although peritoneal dialysis technology and the management of PD patients have been improved significantly,the mortality of PD patients remains high.It’s reported that the total annual mortality of PD patients is about 9.9%in our country,cardiovascular disease(CVD)is the main cause of death,accounting for about 40%of the total mortality in ESRD patients.Therefore,it has become an extremely important in daily clinical work to reduce the cardiovascular complications and mortality of peritoneal dialysis patients,improve the efficiency of peritoneal dialysis treatment and the life quality of patients,find and effectively control risk factors related to peritoneal dialysis,and take scientific and efficient preventive and therapeutic measures.The traditional risk factors of peritoneal dialysis such as age,hypertension,diabetes,obesity,dyslipidemia,have been widely recognized.Many peritoneal dialysis patients have benefited from the regulation of these major risk factors.However,the mortality of peritoneal dialysis patients remains high,and traditional drug treatment have little effect on some patients,which brings great challenges to the prevention and treatment of peritoneal dialysis.It also suggests that the deaths of peritoneal dialysis patients are systemic complex pathophysiological process.There are still some new non-traditional factors that need to be studied and discussed.Bilirubin is a catabolism product of heme,including total bilirubin(TBIL),indirect bilirubin and direct bilirubin.As one of the indicators of liver function test,it is often used to assess the degree of jaundice.It is considered a toxic substance of central nervous system.In recent years,studies have shown that serum bilirubin level is significantly related to the risk of all-cause death from many common diseases(chronic obstructive pulmonary disease,coronary heart disease,ischemic stroke,malignant tumors,etc.).Previous domestic and foreign studies have reported the association between serum bilirubin level and tmortality in PD patients,but conclusions of various studies are different,so further studies are needed to help provide more evidence for subsequent meta-analysis.ObjectiveSerum bilirubin is confirmed to be related to the adverse outcomes in many diseases.But evidence predicting risk of death in PD patients is still limited.This study retrospectively analyzed the clinical data of continuous ambulatory peritoneal dialysis(CAPD)patients at the First Affiliated Hospital of Zhengzhou University to investigate the association between serum bilirubin level and all-cause and CVD mortality in CAPD patients.Methods1.217 end-stage renal disease patients undergoing continuous ambulatory peritoneal dialysis were recruited in this study at the First Affiliated Hospital of Zhengzhou University from September 1,2012 to May 31,2019.All the patients performed the peritoneal dialysis catheterization at the first time in this hospital.Exclusion criterias:(1)The age of patients was less than 18 years old.(2)Maintenance peritoneal dialysis time was less than 3 months.(3)Lost to follow-up.(4)Serum bilirubin level was not tested within 3 months before peritoneal dialysis.(5)The peritoneal balance test has not been performed and assessed the adequacy of dialysis.(6)Hemodialysis has been received for more than 3 months or kidney transplantation history before peritoneal dialysis.(7)Hepatitis B,hepatitis C virus positive or liver transaminase,serum bilirubin levels were elevated.2.In this retrospective cohort study,all patients were followed up from initial peritoneal dialysis to death,switched to hemodialysis or kidney transplantation,or until August 31,2019.We collected the latest clinical baseline data of patients within 3 months before the initial peritoneal dialysis:(1)Demographic data:age,gender.(2)Primary kidney disease.(3)Comorbidities:cardiovascular disease,hypertension,diabetes,chronic pulmonary diseases.(4)Laboratory examination indicators:total bilirubin,plasma albumin,hemoglobin,blood creatinine,estimated glomerular filtration rate(eGFR).(5)Peritoneal dialysis related indicators:results of peritoneal equilibration test and dialysis adequacy test within 1 to 3 months of peritoneal dialysis.(6)Survival time and clinical outcomes.3.Spearman correlation analysis was used for correlation between baseline data and serum total bilirubin.Kaplan-Meier method was used to draw the survival curve,Log-Rank test was used to compare the differences in survival rates among groups,and the Cox proportional hazard regression model predicted the association between serum bilirubin level and all-cause and CVD mortality in peritoneal dialysis patients.Results1.A total of 217 patients were enrolled in this study,among them there were 136 male patients(62.7%),the median age was 45(35.5,52)years old,and the median age of dialysis was 20(11,44)months.The primary kidney diseases leading to end-stage renal disease were chronic glomerulonephritis(112,51.6%),hypertensive renal damage(43,19.8%),diabetic nephropathy(25,11.5%),polycystic kidney(28,12.9%),other diseases(9,4.1%).2.The median of baseline serum TBIL was 4.6(3.6,6.1)μmol/L.All patients were divided into 3 groups according to their tertiles:low serum TBIL group(TBIL≤4.0μmol/L,72 patients),medium serum TBIL group(TBIL=4.0-5.4μmol/L,75 patients)and high serum TBIL group(TBIL>5.4μmol/L,70 patients).There were statistically significant differences in diastolic blood pressure,white blood cell count,blood magnesium,plasma albumin,total urine point protein,total Kt/V and the proportion of diabetes.3.Spearman correlation analysis showed that serum TBIL level was positively related to age,total iron binding capacity,white blood cell count,and hemoglobin,negatively related to plasma albumin,total urine protein,and total urine protein in 24 hours,and had no statistically significant relation with other laboratory examination indexes and comorbidities.4.Until August 31,2019,a total of 55 deaths occurred in 217 patients,among them 33 patients died of cardiovascular disease,9 patients died of infection,3 patients died of malignant tumors,and 10 patients died of other causes.There were significant differences in all-cause and CVD mortality among the three groups(all P<0.05).Kaplan-Meier survival curve showed that the survival rate of all-cause(Log-rankχ2=7.320,P=0.026)and CVD mortality(Log-rank χ2=6.739,P=0.034)of low serum TBIL group was significantly higher than that of medium and high serum TBIL group patients.5.The overall median survival time was 70(37,>81)months.The median survival time of low,medium and high serum TBIL group were>75(56,>75),63(28,>81)and 58(30,70)months,respectively.The adjusted multivariate Cox regression analysis showed that the risk of all-cause mortality in low serum TBIL group was reduced by 63.5%(HR=0.365,95%CI:0.140～0.952,P=0.039)compared with medium serum TBIL group.Compared with the medium serum TBIL group,the risk of CVD mortality in low serum TBIL group was reduced by 79.2%(HR=0.208,95%CI:0.051-0.858,P=0.030).Conclusion1.Serum TBIL level is correlated with multiple clinical indicators of CAPD patients.2.Low serum TBIL level is an independent protective factor for all-cause and CVD mortality of CAPD patients. |
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