Association of serum bilirubin levels with mortality in patients with diabetes initiating chronic hemodialysis: a competing risks analysis of a single-center cohort

Abstract

Background: Evidence remains scarce regarding the property of serum bilirubin levels as a prognostic factor for the incidence of mortality in dialysis patients. Here, we aimed to examine the association between serum bilirubin levels and mortality in patients with diabetes initiating hemodialysis. Methods: This was a single-center, observational, historical cohort study of 395 Japanese patients with diabetes initiating chronic hemodialysis. There were 98 women and 297 men, and the mean (±SD) age was 61 ± 12 years. Patients were dichotomized at the baseline median level of serum bilirubin (0.3 mg/dL). The endpoints were the incidence of all-cause and cause-specific mortality. Hazard ratios for these endpoints were estimated using the Fine-Gray subdistribution hazard model and cause-specific hazard model because of the presence of competing risks. Results: During a median follow-up period of 3.9 years (range; 0.0-10.7 years), there were 83 cases of death, consisting of 39 and 44 cases from atherosclerotic cardiovascular diseases (ASCVDs) and non-ASCVDs, respectively. In the multivariate competing risks analysis, patients with lower bilirubin levels were associated with higher risk of ASCVD-related mortality (subdistribution hazard ratio 3.57, p = 0.015) but not with non-ASCVD-related mortality (0.83, p = 0.665) than those with higher bilirubin levels. Analysis treating bilirubin levels as a continuous variable, as well as cause-specific models yielded the similar results. Conclusions: Lower serum levels of bilirubin may be predictive of higher risk of ASCVD-related mortality in patients with diabetes initiating chronic hemodialysis. There was no relationship between levels of bilirubin and non-ASCVD-related mortality.

Cause-Specific Risk Factors of Death in Individuals with Diabetes: A Competing Risks Modeling

“…Despite the popularity of competing risks modeling in various disciplines of medicine, studies using this approach in the diabetes context are not frequent (12-14). In a recent study, the risk of death from CVD, cancer, and other (non-cardiovascular-non-cancer) causes has been evaluated without evaluating risk factors of each death type (2).…”