Association Between the Ratio of Blood Urea Nitrogen to Serum Albumin, All‐Cause and Cardiovascular Mortality, and Cardiovascular Disease Risk in USA Adults: An Observational Cohort Analysis

ABSTRACT Background and Aims While the blood urea nitrogen to albumin ratio (BAR) has shown prognostic value in critically ill and advanced heart failure patients, its relevance in the general population remains unclear. This investigation sought to explore the correlation between BAR and the risk of CVD as well as mortality in this population. Methods This observational cohort analysis involved 14,786 participants, with data sourced from the National Health and Nutrition Examination Survey (NHANES). In this study, the mortality data of the participants came from the regularly updated National Death Index. The follow‐up for mortality ended on December 31, 2019. We employed multivariate Cox proportional hazards models and restricted cubic spline analyses to assess relationships between BAR and outcomes, adjusting for demographic, lifestyle, and clinical factors. BAR was analyzed as a continuous variable in all primary analyses. To ensure stability, analyses were carried out on subgroups, threshold effects, and sensitivity. Results During an average follow‐up period of 59 months, the study recorded 943 all‐cause deaths and 307 cardiovascular deaths. Based on the weighted logistic regression, higher BAR demonstrated an increased risk of CVD (OR = 1.134, 95% CI 1.076–1.196), especially heart failure (OR = 1.206, 95% CI 1.146–1.270). Higher BAR showed an increased risk for all‐cause mortality (HR = 1.169, 95% CI:1.120–1.220), cardiovascular mortality (HR = 1.240, 95% CI:1.178–1.306). The Kaplan‐Meier curves also suggest that an increased prevalence of all‐cause and cardiovascular mortality in individuals exhibiting higher BAR levels. A nonlinear relationship was observed between the BAR and all‐cause mortality, with a potential inflection point around 2.8 mg/g. Conclusions Elevated BAR index is independently associated with higher incidence of cardiovascular disease and cardiovascular disease mortality. This association highlights the importance of risk assessment and preventive health measures in general population healthcare.