N-terminal pro-brain natriuretic peptide and cardiorenal outcome in patients with anaemia in chronic kidney disease

Aims: Blood levels of N-terminal pro-brain natriuretic peptide (NT-proBNP) may be modified by low renal clearance and anaemia. The aim of this study was to investigate the impact of the blood NT-proBNP level on cardiovascular and renal outcomes in patients with these two manifestations.

Methods: This post hoc analysis stemmed from the oBservational clinical Research In chronic kidney disease patients with renal anemia: renal proGnosis in patients with Hyporesponsive anemia To Erythropoiesis-stimulating agents, darbepoetiN alfa (BRIGHTEN) trial, a large prospective study involving patients with non-dialysis kidney disease experiencing anaemia. The Pearson correlation coefficient was employed to examine the association of baseline NT-proBNP level with renal function or anaemia. Longitudinal assessment of the association of baseline blood NT-proBNP levels with cardiovascular outcomes (cardiac death, acute coronary syndrome, hospitalization due to heart failure or fatal arrhythmia) and renal outcomes [the initiation of maintenance dialysis, kidney transplantation, a 50% decrease in the estimated glomerular filtration rate (eGFR) or an eGFR of ≤6 mL/min/1.73 m²] was conducted by using restricted cubic spline analysis and Cox proportional hazard model analysis.

Results: In total, this study included 1484 patients [mean age, 70.2 ± 11.8 years; women, 40.6%; eGFR, 20.3 ± 9.6 mL/min/1.73 m²; haemoglobin (Hb) level, 9.8 ± 0.9 g/dL]. Baseline NT-proBNP levels were a median of 496.0 pg/mL [inter-quartile range: 235.0-1090.0 pg/mL]. A weak association existed between NT-proBNP levels, on a logarithmic scale, and eGFR (r = -0.131, P < 0.001) or Hb levels (r = -0.182, P < 0.001) at baseline. During 2.29 ± 0.89 years, 92 cardiovascular and 573 renal events were recorded. After adjusting for potential confounders such as eGFR and blood Hb level, a nonlinear relationship existed between blood NT-proBNP levels and cardiorenal outcomes. Patients with a baseline NT-proBNP level ≥1000 and 500-1000 pg/mL exhibited a greater risk for cardiovascular outcomes than did patients with an NT-proBNP level <250 pg/mL {hazard ratio [HR] = 8.10 [95% confidence interval (CI), 2.80-23.40] and 3.35 [95% CI, 1.10-10.18], respectively}. These patients also exhibited a moderate risk for renal outcomes [HR = 1.77 (95% CI, 1.36-2.31) and 1.54 (95% CI, 1.19-2.00), respectively].

Conclusions: NT-proBNP provides prognostic insights into cardiovascular and renal outcomes among patients with advanced chronic kidney disease experiencing anaemia.