Blood urea nitrogen to serum albumin ratio as a new indicator of disease severity and prognosis in idiopathic pulmonary artery hypertension

Background Emerging evidence has shown that the blood urea nitrogen to serum albumin ratio (BAR) is associated with the severity and prognosis of heart failure. However, its role in idiopathic pulmonary arterial hypertension (IPAH) remains unclear. This study investigated the associations between BAR and functional status, echocardiographic findings, hemodynamics, and long-term outcomes among patients with IPAH. Methods This study included consecutive patients who underwent right heart catheterization (RHC) and were diagnosed with IPAH between January 2013 and January 2018 at Fuwai Hospital. The primary outcome was the worsening of clinical symptoms. Spearman correlation coefficients were used to evaluate the association between the BAR and established markers of IPAH severity. Receiver operating characteristic (ROC) curve analysis was used to determine BAR's optimal cut-off and predictive performance. Kaplan–Meier analysis and Cox proportional hazard models assessed the relationship between BAR and clinical worsening. Results A total of 340 patients with IPAH were included in this study. BAR correlated with well-validated variables that reflected the severity of IPAH, such as World Health Organization functional class, 6-min walk distance, N-terminal pro-brain natriuretic peptide (NT-proBNP) level, mixed venous oxygen saturation, and cardiac index. Kaplan–Meier curves indicated that patients with BAR>3.80 had a significantly higher clinical worsening rate (log-rank test, P < 0.001) than those with BAR≤3.80. Multivariate Cox analysis showed that BAR could independently predict clinical worsening [hazard ratio(HR):1.177, 95% confidence interval (CI):1.014-1.367, P=0.005]. In addition, BAR provided additional predictive value for the European Society of Cardiology (ESC)/European Respiratory Society (ERS) risk assessment score. Conclusions BAR reflects disease severity and is independently associated with the prognosis of patients with IPAH.