Association between blood urea nitrogen-to-albumin ratio and mortality in ICU patients with chronic obstructive pulmonary disease: data from the MIMIC IV database

This study aims to investigate the association between blood urea nitrogen to albumin ratio (BAR) and short- and long-term mortality among intensive care unit (ICU) patients with chronic obstructive pulmonary disease (COPD). Patients diagnosed with COPD based on International Classification of Diseases 9th and 10th Revisions diagnosis codes in the Medical Information Mart for Intensive Care IV (version 2.2) database were screened. Outcomes included 28-day, 90-day, 180-day, and 1-year mortality after ICU admission. Receiver operating characteristic (ROC) curve, concordance index (C-index), Kaplan–Meier (K–M) survival curve, logistic regression analyses, and subgroup analysis were performed to assess the clinical utility of BAR. This study included 1,067 patients. The 28-day, 90-day, 180-day, and 1-year mortality rates were 24.9%, 31.8%, 37.3%, and 44.8%, respectively. The ROC curve analysis and C-index indicated that admission BAR had moderate predictive ability for short- and long-term all-cause mortality in critically ill patients with COPD. Logistic regression revealed that BAR was an independent adverse predictor for short- and long-term mortality. K–M curves indicated a significant difference in short- and long-term survival (p < .001) among different BAR groups. No significant interaction was observed by subgroup analysis across all subgroups stratified by comorbidities. This study demonstrated that an elevated BAR is significantly associated with increased short- and long-term mortality among critically ill patients with COPD admitted to the ICU. Given its availability and low cost, BAR may serve as a practical prognostic tool in clinical settings.