Analytical Evaluation of a BNP Assay on the New Point-of-care Platform ResponsIQ

a) Objectives: responsIQ is a new point-of-care (POC) immunoassay platform utilizing evanescent field total internal reflection fluorescence (TIRF) detection and active microfluidics controlled by optical sensors. A B-type natriuretic peptide (BNP) assay was developed on this system. The objective was to show that the BNP test fulfils the basic requirements regarding analytical performance, storage stability of cartridges and correlation to reference systems to be used as a POC test. b) Design and methods: Analytical sensitivity and imprecision were determined in 10 separate experiments over a period of one year. Cartridge storage stability at 4-7 °C and 37 °C was tested. The correlation of responsIQ whole blood measurements to a POC reference device and a laboratory analyzer was determined using 100 patient samples. c) Results: Limit of detection (LOD) was 2.3±1.0 pg/ml BNP and within-run coefficient of variation (within-run CV) was 4.8±1.4% down to a concentration of <40 pg/ml BNP. Cartridge storage stability at 4-7 °C was greater than 50 weeks and at 37 °C, stability was three weeks. The correlation of responsIQ results with both reference methods was high (≥0.972). d) Conclusions: The developed BNP test fulfils the basic requirements for the performance parameters defined above. The test׳s sensitivity was in the performance range of laboratory analyzer BNP tests. This is the first extensive proof of concept of the responsIQ system.