Journal of Advanced Intensive and Critical Care Medicine

Abstract

Background: Simple, readily available biomarkers that reflect disease severity in critically ill patients are of significant clinical interest. The blood urea nitrogen-to-albumin (BUN/ALB) ratio has emerged as a potential marker integrating renal function, nutritional status, and systemic illness.

Objectives: To evaluate the association between the BUN/ALB ratio and in-hospital mortality, hospital length of stay (LOS), intensive care unit (ICU) LOS, and vasopressor requirements among ICU patients.

Methods: We conducted a retrospective cohort study of adult ICU admissions. The primary outcome was in-hospital mortality. Secondary outcomes included hospital LOS, ICU LOS, and number of vasopressors administered. Multivariable logistic regression was used to evaluate associations with mortality, while negative binomial regression models were used for count outcomes. Models were sequentially adjusted for demo graphic variables, laboratory values, and comorbidities.

Results: A total of 1,879 unique ICU admissions were included. The median BUN/ALB ratio was 6.7 (Q1 Q3: 4.3–12.4). Higher BUN/ALB ratios were associated with increased odds of in-hospital mortality in adjusted models without comorbidities (OR 1.03 per unit increase; 95% CI 1.01–1.04), but this association was attenuated after adjustment for comorbidities. The BUN/ALB ratio remained independently associated with hospital LOS after full adjustment (IRR 1.011; 95% CI 1.005–1.016). Associations with ICU LOS and vasopressor use were no longer significant after accounting for comorbidities.

Conclusions: The BUN/ALB ratio is associated with markers of disease severity, particularly hospital LOS, among critically ill patients. However, comorbid conditions appear to drive much of the observed association with mortality and ICU-level outcomes. The BUN/ALB ratio may serve as a useful adjunctive marker of illness burden rather than an independent predictor of mortality.