What are the differences in brain natriuretic peptide (BNP) and N-terminal prohormone of brain natriuretic peptide (NT-proBNP) assays?

Updated: Jan 08, 2018
  • Author: Donald Schreiber, MD, CM; Chief Editor: Erik D Schraga, MD  more...
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Answer

Answer

In addition to the studies described above, head-to-head comparisons of BNP and NT-proBNP assays have been performed. [7, 29, 30, 31, 32, 33, 34]

In a study by Richards et al, BNP and NT-proBNP had nearly identical performance characteristics in detecting a left ventricular ejection fraction (LVEF) of less than 30% and in predicting hospital admission and cardiac mortality rates. Similar confounding effects of age, sex, and renal insufficiency were discovered. [30]

The study, one of the largest comparisons of BNP and NT-proBNP assays, was conducted in New Zealand in more than 1000 patients with stable heart failure. The goal was to compare BNP and NT-proBNP test results with several clinical variables. Age, sex, BMI, LVEF (measured on radionuclide scanning), and estimated creatinine clearance were determined, in addition to BNP and NT-proBNP levels. Endpoints were hospital admission and all-cause mortality over 12 months. Because the study patients had stable heart failure, it is unclear if the results can be extrapolated to ED patients with acute dyspnea and acute CHF.

NT-proBNP is most sensitive for the detection of mild left ventricular (LV) dysfunction and structural heart disease identified during echocardiography. The clinical significance of this performance characteristic is unclear because most of the patients had no symptoms of acute CHF. BNP was less sensitive to the effects of renal insufficiency than NT-proBNP, and the clinical utility of having only single cutoff thresholds for ruling in acute CHF may be an advantage in some settings.

More clinical studies have addressed BNP than NT-proBNP. However, the present authors know of no specific study data that clearly establishes a diagnostic advantage of one natriuretic peptide over the other.

Current licensing and patent rules limit the BNP and NT-proBNP assays to specific laboratory instrumentation platforms. One company may not have the required licensing permits to perform BNP (or NT-proBNP) testing. The laboratory instrumentation platform already in place at that institution, and not necessarily any objective evaluation of the assay, determines the particular assay available at any one hospital.

The table below summarizes the evidence-based cutoff values proposed for the diagnosis of CHF in the patient with dyspnea who presents to an acute-care facility. The corresponding likelihood ratios and predictive values are also summarized.


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