Comparison of a Fully Automated Immunoassay with a Point-of-Care Testing Method for B-Type Natriuretic Peptide

The clinical relevance of B-type natriuretic peptide (BNP) as a diagnostic tool and prognostic marker in patients with cardiovascular diseases has been confirmed recently (1)(2)(3). Over the last 5 years, several immunoassay methods for the measurement of BNP, which share some analytical characteristics, such as full automation, turnaround time <60 min, lower imprecision, and/or better analytical and functional sensitivity, have become commercially available (1)(4). The analytical performance and diagnostic accuracy of immunoassays for BNP were compared recently (5)(6). In the present study, we evaluated the analytical performance and diagnostic accuracy of an automated immunochemiluminescent assay for BNP (ACCESS System; Beckman Coulter). We also compared its performance and accuracy with the TRIAGE BNP test (Biosite). The 2 immunoassays use as antigen the intact BNP 1–32 peptide and the same mouse anti-human BNP antibodies. The capture antibody (Scios) recognizes the peptide ring, whereas the detection antibody (Biosite) recognizes an epitope between amino acids 5 and 10 at the NH2 terminus (6)(7). All statistical analyses were performed by use of parametric tests after log transformation of the original data. Nonparametric tests were also performed and showed identical statistical trends.We collected blood samples from 91 healthy individuals [51 women and 40 men; mean (SD) age, 43.2 (13.4) years; range, 16–71 years] and 214 patients with idiopathic or secondary cardiomyopathy (only 21 with a left ventricular ejection fraction >50%). Blood was collected between 0800 and 0900 after the individuals had fasted overnight and had rested for 20 min in a supine position. Immediately after withdrawal, blood samples (8–10 mL) were placed in ice-chilled disposable polypropylene tubes containing EDTA (1 mg/mL of plasma). Plasma samples were obtained shortly after venipuncture by centrifugation for 15 min at 4 °C and then were …