Comparison of Plasma B-type Natriuretic Peptide (BNP) Levels, N-terminal Pro B-Type Natriuretic Peptide (NT-proBNP) Levels, and the NT-proBNP-to-BNP Ratio in Patients with CKD

Background: Both B-type natriuretic peptide (BNP) and N-terminal pro-B-type natriuretic peptide (NT-proBNP) are utilized for diagnosing and managing patients with heart failure in clinical settings. These parameters are also known to be elevated by other cardiovascular disease (CVD), such as coronary artery disease, arrhythmia, and valvular disease. However, their levels can also be influenced by numerous clinical factors including kidney function, and the details remain unclear in patients with chronic kidney disease (CKD). Then, we assess the clinical factors which can influence BNP levels, NT-proBNP levels, and the BNP/NT-proBNP ratio and their predictive availability for CVD in patients with advanced stage CKD. Methods: This study included 1,037 patients who visited the division of Nephrology at our hospital between 2014 and 2015. For all study participants, both plasma BNP and NT-proBNP levels were measured simultaneously. Plasma BNP levels, NT-proBNP levels, and the BNP/NT-proBNP ratio were evaluated in each stage of CKD, and also examined a correlation of clinical factors with them. Furthermore, we assessed the correlation of BNP levels, NT-proBNP levels, the BNP/NT-proBNP ratio, and clinical parameters with CVD events in patients with CKD stage 4 and 5. Results: Patients with CKD stage 1-5D were included in this study. Plasma BNP levels, NT-proBNP levels, and the NT-proBNP/BNP ratio increased and the relationship between BNP and NT-proBNP levels weakened with declining kidney function. In patients with CKD stage 1 to 5, common independent determining factors for BNP and NT-proBNP levels and the NT-proBNP/BNP ratio included Hb levels, phosphate levels, and intact PTH levels. In patients with advanced stage CKD (CKD4 and 5), those with higher levels of BNP, NT-proBNP, or the NT-proBNP/BNP ratio experienced a greater number of CVD events compared to those with lower levels. Additionally, multivariate Cox regression analysis showed that the occurrence of CVD was significantly correlated not with BNP and NT-proBNP levels, but only with the NT-proBNP/BNP ratio (HR [95%CI]: 1.064 [1.029-1.100], p<0.001) in these patients. Conclusion: Given the complex influence of various factors on plasma BNP and NT-proBNP levels in patients with CKD, careful interpretation of these values is essential. Funding: Commercial Support - Roche