Increased Blood Urea Nitrogen-To-Creatinine Ratio is an Independent Predictor of Mortality in Patients with End-Stage Renal Disease.

Abstract

Background: End-stage renal disease (ESRD) is the final phase of chronic kidney disease, characterized by severe renal dysfunction that leads to metabolic disturbances in blood urea nitrogen (BUN) and serum creatinine (Scr). Currently, the relationship between the BUN/creatinine ratio (BCR) and all-cause mortality in patients with ESRD remains unclear. This study aimed to investigate the predictive value of BCR for short-term (60-day) and intermediate-term (365-day) all-cause mortality risk in patients with ESRD.

Methods: By using data from the MIMIC-IV database, we included patients with ESRD meeting ICD-9/ICD-10 diagnostic criteria, excluding those aged < 18 years, non-intensive care unit admissions, and those with incomplete information, ultimately enrolling 2,102 patients. The participants were stratified according to the BCR quartiles. Kaplan-Meier survival analysis and multivariate Cox regression were used to compare differences in all-cause mortality between the groups. Restricted cubic spline (RCS) analysis was used to examine the dose-response relationship between BCR and all-cause mortality. Subgroup analysis was used to assess result stability, and receiver operating characteristic (ROC) curves were used to compare the predictive performance of BCR versus individual markers (BUN or Scr).

Results: This study included 2,102 patients with ESRD. The results demonstrated a positive correlation between BCR and 60- and 365-day all-cause mortality rates. Multivariate Cox regression analysis revealed that each one-unit increase in BCR was associated with a 3% higher risk of 60-day all-cause mortality (HR = 1.03, 95% CI: 1.01 - 1.04) and 365-day all-cause mortality (HR = 1.03, 95% CI: 1.01 - 1.04). The RCS analysis showed a linear relationship between BCR and 60-day all-cause mortality (p-overall < 0.001, p-non-linear = 0.237), whereas a non-linear relationship was observed for 365-day all-cause mortality (p-overall < 0.001, p-non-linear = 0.018). The subgroup analysis revealed no significant interaction effects. ROC analysis indicated the superior predictive performance of BCR compared to BUN or Scr alone.

Conclusions: BCR serves as an independent predictor of all-cause mortality risk in patients with ESRD and may provide a novel reference index for clinical prognosis assessment.