Lower serum bilirubin is a risk factor for cardiovascular mortality in maintenance hemodialysis patients: a retrospective cohort study

Background: Although recent studies showed serum bilirubin, an endogenous antioxidant, is protective against cardiovascular diseases, cancer, and diabetic complications, less information is available its association with cardiovascular mortality in hemodialysis patients. This study aimed to investigate the relationship between serum bilirubin and the cardiovascular mortality in maintenance hemodialysis patients. Methods: : This retrospective study included 284 chronic hemodialysis patients who started hemodialysis between January 01, 2003, and May 30, 2019. The endpoint was cardiovascular death and all-cause death. A Cox proportional hazards model was used to evaluate the risk factors for cardiovascular death in the maintenance hemodialysis. The cardiovascular mortality was evaluated by Kaplan-Meier analysis. Results: : Up to 2019, the median follow-up time was 53 months. In Kaplan–Meier analysis curves, the risk of cardiovascular death in the patients with serum indirect bilirubin (IBIL) levels＜3.0 μmol/L was significantly higher than those with serum IBIL levels≥3.0 μmol/L( p =0.045). In multivariate Cox regression analysis, the risk of cardiovascular mortality in patients with serum IBIL levels ≥3.0 μmol/L was 0.556 times the risk in patients with serum IBIL levels＜3.0 μmol/L (Hazard ratio=0.556, 95% confidence interval 0.334~0.926, p =0.024). However, there was no significant association between serum IBIL and all-cause mortality ( p =0.269). Conclusions: : Our findings suggest that low serum IBIL level is independently associated with high risk of cardiovascular death in maintenance hemodialysis patients.