Conversion formula from B-type natriuretic peptide to N-terminal proBNP values in patients with cardiovascular diseases

Abstract

BackgroundAlthough B-type natriuretic peptide (BNP) and N-terminal prohormone B-type natriuretic peptide (NT-proBNP) are released in equimolar proportions, their values differ depending on clinical conditions. A useful conversion formula between BNP and NT-proBNP remains to be developed for the clinical use. AimTo develop a conversion formula from BNP to NT-proBNP. MethodsIn the derivation cohort, 923 patients with chronic heart failure, in whom both BNP and NT-proBNP values were available, were enrolled from our SUPPORT (Supplemental Benefit of ARB in Hypertensive Patients with Stable Heart Failure using Olmesartan) trial. The validation cohort included 1154 consecutive patients with or at risk of cardiovascular diseases, in whom both BNP and NT-proBNP values were measured simultaneously at Tohoku University Hospital. We regressed log10 NT-proBNP onto log10 BNP and factors influencing BNP and NT-proBNP values. ResultsWe adopted the model with the smallest Akaike information criterion consisting of log10 BNP, age, sex, BMI, creatinine clearance (CCr), hemoglobin, and atrial fibrillation (AF). As compared with the previously reported conversion formulas, the present conversion formula utilized non-linear transformation by spline function, and exhibited the strongest correlation between actual and calculated values of NT-proBNP (r = 0.928). The root mean squared error (RMSE) of the present conversion formula was smallest compared with the previously reported conversion formulas, indicating that this formula most effectively converts BNP values to NT-proBNP values. ConclusionsWe have developed a useful conversion formula from BNP to NT-proBNP values, using age, sex, BMI, CCr, hemoglobin, and AF, which could be widely used in daily clinical practice.