Comparison of immunoassays for NTproBNP conducted on three analysis systems: Milliplex, Elecsys and RIA.

ABSTRACT

OBJECTIVES: The aim of this study was to evaluate a Milliplex NTproBNP immunoassay and to compare its performance with the Roche Elecsys assay and an in house NTproBNP radioimmunoassay (RIA). DESIGN AND METHODS: Samples were analyzed for NTproBNP in all 3 assays following the manufacturer's instructions and/or our previously published methodologies. RESULTS: Similar plasma concentrations and assay reproducibility were observed for the Roche assay and in house RIA. However, the Milliplex assay produced much lower concentrations than the other two assays (versus Roche Elecsys bias of -367.9 pg/mL, (LOA -907.6 and 171.8)), and only quantified results for 63 of the 111 samples assessed. Of these 46 samples had acceptable errors of measurement (within sample coefficients of variation <20%) equating to 41% of the total samples measured. CONCLUSIONS: The Milliplex assay, in its current form, does not produce results comparable with the Roche Elecsys 2010 assay or our in house RIA, and does not perform well as a quantitative assay. It may provide qualitative results (ie high, medium or low concentration), and serve as a rudimentary screening assay.