Relationship between serum bilirubin levels and mortality in patients on peritoneal dialysis

Background: Studies have shown that the serum total bilirubin (TBil) is associated with the mortality of the general population and of hemodialysis patients. However, few studies have examined the associations of the direct bilirubin (DBil) and indirect bilirubin (IBil) with the mortality of peritoneal dialysis (PD) patients. Methods: This was a retrospective cohort study. Clinical and laboratory data were collected from 740 PD patients. The primary endpoint was 5-year all-cause mortality. Survival analysis was performed using the Kaplan-Meier method with the log-rank test. The mortality hazard ratio was evaluated using Cox regression models. Results: Among the 740 PD patients, the mean age was 49.9 ± 15.0 years, 54.9% were men, and 20.3% had diabetes. During the median follow-up period of 28 months (interquartile range, 14-41 months), 178 patients died. Kaplan-Meier analysis revealed that all-cause mortality was higher in the patients in the higher TBil group than in the lower TBil group (25.6% vs. 18.3%, p = .017) and in patients in the higher IBil group than in the lower IBil group (24.3% vs. 19%, p = .026). Multivariate analysis showed that compared with the lower TBil group, the 5-year mortality risk was higher in the higher TBil group (HR = 1.69, 95% CI: 1.11-2.56, p = .014). Similarly, there was a 56% higher risk of 5-year mortality in the higher IBil group than in the lower IBil group (HR = 1.56, 95% CI: 1.04-2.34, p = .032). However, no such associations were observed between the DBil and the mortality risk. Conclusions: The baseline serum TBil and IBil levels were significantly associated with 5-year all-cause mortality among PD patients.