Correlation between serum total bilirubin level and all cause death and cardiovascular event death in patients with peritoneal maintenance dialysis

Objective To investigate the correlation between serum total bilirubin level and all-cause mortality in peritoneal maintenance dialysis patients. Methods A single-center, retrospective and cohort study was conducted. A total of 126 patients with peritoneal dialysis, performed for 3 months or more in the department of nephropathy, second affiliated hospital of kunming medical university from January 1, 2013 to December 31, 2015, were enrolled. Demographic data, baseline clinical and laboratory test data from these patients were collected. All patients were followed up until 31 December 2018. The patients were divided into two groups according to the level of serum total bilirubin binary. Kaplan-Meier method was used to compare the survival rates of the two groups. COX regression model was used to analyze the correlation between serum total bilirubin and all-cause mortality and cardiovascular event mortality. Spearman correlation analysis was used to analyze the influencing factors of low serum total bilirubin level. Results A total of 126 patients with continuous peritoneal dialysis were enrolled in this study. The age of the patients was (52.8±13.5) and 83 of them were males (65.9%). Dialysis age was 25 (13,39) months. 42 patients died during the follow-up period. The all-cause mortality rate of the low serum total bilirubin group was 43.1% (28/65), and that of the high serum total bilirubin group was 23.0% (14/61), with statistically significant difference (P=0.017). There were statistically significant differences in serum total bilirubin (TBIL), urea nitrogen (BUN), creatinine (CREA), eGFR, phosphorus, calcium and phosphorus product between the two groups. Age, sex, hypertension, systolic pressure,diastolicpressure,diabetes mellitus, heart failure, left ventricular hypertrophy, coronary heart disease, cerebrovascular accident, HBV, HCV, dialysis age, serum leukocyte, ALT,AST,ALP,GGT,TBA, uric acid, iron, total cholesterol, triglyceride, albumin, blood sugar, hematocrit, C-reactive protein and parathyroid hormone had differences between the two groups with no statistical significance. Kaplan-Meier survival curve showed that the survival rate of patients with serum TBIL ≤ 5.9 mmol/L was significantly lower than that of patients with TBIL >5.9 mmol/L (P=0.001). Fully corrected multivariate COX regression analysis showed that low serum TBIL was an independent risk factor for all-cause mortality (HR=2.855 95% CI:1.476~5.524,P=0.002) in patients undergoing continuous peritoneal dialysis, and was associated with cardiovascular event mortality (HR=3.5011 95% CI:1.442~8.498,P=0.006). Conclusions TBIL is associated with all-cause mortality risk and cardiovascular mortality risk in CAPD patients.