Analytical and clinical evaluation of a rapid quantitative lateral flow immunoassay for measurement of soluble ST2 in human plasma

BACKGROUND: Soluble ST2 (sST2) is gaining growing interest as a biomarker in heart failure. So far, the ELISA-format is widely used for commercially available ST2 assays, which hampers their use in clinical routine. Recently, a rapid quantitative lateral flow immunoassay for the measurement of sST2 in human plasma has been developed. METHODS: We evaluated precision and linearity of the ASPECT-PLUS ST2 test, and performed an analytical and clinical assay comparison with the MBL and the PRESAGE ST2 ELISAs. We measured sST2 with these three assays in a clinical cohort of 251 consecutive patients with acute dyspnea as the chief compliant (i.e., 137 patients with dyspnea attributable to heart failure and 114 patients with dyspnea attributable to other reasons). RESULTS: Within-run and total coefficients of variation of the ASPECT-PLUS ST2 test were < 17% and the assay was linear across its measurement range. We found a constant and proportional bias between the MBL ST2 assay, the PRESAGE ST2 assay and the ASPECT-PLUS ST2 test, respectively. However, at the proposed cut-off of 35 ng/mL, sST2 results obtained with the PRESAGE ST2 assay and the ASPECT-PLUS ST2 test were similar. Testing clinically, the three assays deemed equally useful for the diagnosis of heart failure (AUC, 0.670 for the MBL ST2 assay vs. 0.626 for the PRESAGE ST2 assay vs. 0.630 for the ASPECT-PLUS ST2 test) and for the prediction of 1-year mortality in dyspnoeic patients (AUC, 0.743 for the MBL assay vs. 0.742 for the PRESAGE ST2 assay vs. 0.752 for the ASPECT-PLUS ST2 test). CONCLUSION: The ASPECT-PLUS test meets the analytical requirements for point-of-care testing. Test results of the ASPECT-PLUS ST2 and the PRESAGE ST2 methods were comparable at the proposed cut-off, and the diagnostic/prognostic capabilities of the three methods were similar.