Relationship Between Serum Indirect Bilirubin Levels and Cardiovascular Events and All-Cause Mortality in Maintenance Hemodialysis Patients

Abstract

Purpose Unconjugated bilirubin is one of the most endogenous antioxidant substances. Mildly elevated total bilirubin concentrations may protect against cardiovascular disease and total death. However, most studies only focused on the association between serum total bilirubin and the risk of cardiovascular disease and total death. This study aimed to investigate the relationship between serum indirect bilirubin (IBIL) and the cardiovascular events in maintenance hemodialysis patients. Patients and Methods: This retrospective cohort study included 284 maintenance hemodialysis patients. Patients were divided into two groups according to the median IBIL level: high IBIL group (IBIL ≥3.0 μmol/L) and low IBIL group (IBIL <3.0 μmol/L). All demographic and laboratory data were recorded at baseline. The endpoint was cardiovascular events and all-cause mortality. Results During the median follow-up time of 62 months, 96 patients developed cardiovascular disease. There were 134 deaths. In Kaplan–Meier analysis curves, the risk of cardiovascular events in the low IBIL group was significantly higher than high IBIL group ( P < 0.001). In multivariate Cox regression analysis, the risk of cardiovascular events in high IBIL group was 0.484 times (95% CI 0.278–0.844, P = 0.010) the risk in low IBIL group. However, there was no significant association between serum IBIL level and all-cause mortality ( P = 0.269). Conclusion Our findings suggest that lower circulating IBIL levels were associated with the increased risk of cardiovascular events in maintenance hemodialysis patients.