Improvement of the cardiac marker N-terminal-pro brain natriuretic peptide through adjustment for renal function: a stratified multicenter trial.

BACKGROUND: N-terminal-pro brain natriuretic peptide (NT-proBNP) is a useful cardiac marker that is also influenced by renal dysfunction. It was our objective to assess the relationship between NT-proBNP concentrations in plasma and worsening renal function, and to attempt adjustment of NT-proBNP for renal dysfunction in a prospective, stratified multi-center study.
METHODS: We stratified 203 male patients according to their cardiac status and the estimated glomerular filtration rate (eGFR). Cardiac disease was assessed by medical history, physical examination and standardized echocardiography. Patients were stratified according to the following: absence of cardiac history and abnormalities (control, CTRL, n=66), cardiac history without left ventricular hypertrophy (LVH) or left ventricular systolic dysfunction (LVD) (history, n=30), LVH without systolic dysfunction (LVH, n=68), and LVD [ejection fraction (EF) <40%, LVD, n=39]. Renal disease was stratified according to the eGFR: 15-30 mL/min (n=52), 31-75 mL/min (n=99), and >75 mL/min (n=52).
RESULTS: NT-proBNP was correlated with eGFR in the entire study population and for all levels of cardiac disease (all p<0.01). Regression analysis allowed adjustment of NT-proBNP for eGFR in a continuous manner, and this adjustment significantly improved the predictive value (receiver operating characteristic curve for symptomatic LVD from 0.80 to 0.86, p<0.01; sensitivity from 74% to 83% and specificity from 68% to 79%).
CONCLUSIONS: NT-proBNP correlates inversely and significantly with eGFR throughout all levels of cardiac strata. We propose for the first time a continuous adjustment algorithm which markedly improves the predictive values of NT-proBNP in male patients with impaired renal function.