Blood urea nitrogen to serum albumin ratio as a new prognostic indicator in critical patients with chronic heart failure

Abstract

Aims: Chronic heart failure (CHF) is often a common comorbidity in critically ill patients admitted to the intensive care unit (ICU) and carries an extremely poor prognosis. The study aimed to investigate the relationship between the blood urea nitrogen to serum albumin ratio (BAR) and the prognosis of patients with CHF admitted to the ICU.

Methods and results: This retrospective cohort study included 1545 critically ill patients with CHF as a diagnosed comorbidity admitted to the ICU deposited in the MIMIC-III database, of whom 90 day all-cause mortality was 27.6% (n = 427) and in-hospital mortality was 17.3% (n = 267). The results of multiple logistic regression analysis indicated that BAR is an independent risk factor for in-hospital mortality in critically ill patients with CHF [compared with BAR ≤ 0.83; 0.83 < BAR ≤ 1.24: odds ratio (OR) 2.647, 95% confidence interval (CI) 1.797-3.900, P < 0.001; BAR ≥ 1.24: OR 3.628, 95% CI 2.604-5.057, P < 0.001]. Multiple COX regression analysis found a relationship between BAR and all-cause mortality at 90 day follow-up (0.83 < BAR ≤ 1.24: OR 1.948, 95% CI 1.259-3.014, P < 0.003; BAR ≥ 1.24: OR 1.807, 95% CI 1.154-2.830, P < 0.01; BAR ≤ 0.83 as a reference). Kaplan-Meier curves also showed similar results as well (P < 0.001). The areas under the receiver operating characteristic curves for predicting in-hospital mortality and 90 day all-cause mortality were 0.622 and 0.647, respectively.

Conclusions: BAR is an independent risk factor for in-hospital mortality and 90 day mortality in critically ill patients with CHF admitted to the ICU.

Keywords: Blood urea nitrogen; Critical chronic heart failure; Ratio; Risk factor; Serum albumin.

Figure 1

Study flow diagram depicting exclusion criteria and outcomes. BUN, blood urea nitrogen; ICD‐9, International Classification of Diseases; LVEF, left ventricular ejection fraction.

Figure 2

Hazard ratios of 90 day all‐cause mortality as a function of baseline BAR (BAR as a continuous variable fitted an unadjusted COX regression model using restricted cubic spline regression). BAR, blood urea nitrogen to serum albumin ratio; CI, confidence interval; HR, hazard ratio; RCS, restricted cubic spline.

Figure 3

The ROC curve of all‐cause mortality, (A) ROC curves for in‐hospital mortality comparing BAR with SOFA score; (B) ROC curves for 90 day all‐cause mortality comparing BAR with SOFA score. BAR, blood urea nitrogen to serum albumin ratio; ROC, receiver operating characteristic; SOFA, Sequential Organ Failure Assessment.

Figure 4

Kaplan–Meier survival analysis plot for 90 day overall survival for three different BAR levels. BAR, blood urea nitrogen to serum albumin ratio.