Impact of blood urea nitrogen to creatinine ratio on infectious events, cardiovascular events, and all-cause mortality in patients with hemodialysis: a retrospective cohort study

Background In patients undergoing hemodialysis, serum blood urea nitrogen (BUN) and creatinine (Cr) levels are affected by factors such as diet and muscle mass. Few studies have examined the optimal range of serum BUN/Cr ratios in these patients. Therefore, this study examined the association between the BUN/Cr ratio and all-cause mortality. Methods This retrospective cohort study evaluated pre-dialysis BUN/Cr ratios. Cox regression analysis was performed with all-cause mortality as the outcome and the BUN/Cr ratio as an explanatory factor. Results This study included 1321 patients undergoing hemodialysis (mean age: 63.5 +/- 11.7 years; dialysis duration: 110 [17-203] months; 70.0% male). The mean serum BUN was 65.1 +/- 14.1 mg/dL, Cr was 11.5 +/- 3.1 mg/dL, and BUN/Cr ratio was 5.97 +/- 2.26. During the study, 253 deaths occurred. Using the group with the second-lowest serum BUN/Cr ratio (4.7-5.6) as a reference, the highest BUN/Cr ratio (> 6.8) was associated with a significantly higher mortality rate (hazard ratio [HR], 1.98; 95% confidence interval [95% CI], 1.30-3.03), and the second-highest group (5.6-6.8) had an increased risk of major cardiovascular disease events (HR, 1.67; 95% CI, 1.22-2.28) and infectious events (HR, 1.59; 95% CI, 1.04-2.45). Conclusion Elevated BUN/Cr ratios were associated with increased risks of infectious events, cardiovascular events, and all-cause mortality in patients undergoing hemodialysis.