This study aimed to investigate the association between the blood urea nitrogen-to-albumin ratio (BAR) and both short- and long-term all-cause mortality in critically ill patients with atrial fibrillation (AF). A retrospective cohort study was conducted using the Medical Information Mart for Intensive Care IV (MIMIC-IV) database, including 4,697 critically ill AF patients. Participants were stratified into tertiles based on their BAR levels (Q1: 12.43). The primary outcomes were 30-day and 365-day all-cause mortality. Kaplan-Meier survival curves, multivariable Cox proportional hazards models, and restricted cubic spline (RCS) analyses were employed to assess the association. A two-piecewise linear model was used to identify the threshold effect. Subgroup analyses were performed to evaluate the consistency of the association. Patients in higher BAR tertiles had significantly higher mortality rates at all time points (P < 0.001). After full adjustment for demographics, comorbidities, laboratory parameters, and treatment measures, the highest BAR tertile (Q3) was independently associated with increased risks of 30-day (hazard ratio HR = 2.34, 95% confidence interval CI: 1.94–2.82) and 365-day mortality (HR = 2.04, 95% CI: 1.78–2.35), compared to the lowest tertile (Q1). RCS analysis revealed a nonlinear, L-shaped relationship between BAR and mortality. A threshold effect was identified, with inflection points at BAR levels of 11.52 for 30-day mortality and 14.41 for 365-day mortality. The association remained robust across all predefined subgroups. In intensive care unit (ICU) patients with AF, elevated BAR levels independently predicted increased 30-day and 365-day all-cause mortality risks. The BAR may serve as a useful prognostic indicator for risk stratification and clinical management of AF patients in ICUs.
Wu et al. (Sat,) studied this question.