Analytical and clinical evaluation of a novel high-sensitivity assay for measurement of soluble ST2 in human plasma--the Presage ST2 assay.

BACKGROUND: The protein ST2 is a member of the interleukin-1 receptor family. Blood concentrations of the soluble isoform of ST2 (sST2) are increased in inflammatory diseases and in heart disease and are considered a prognostic marker in both. The aim of this study was the analytical and clinical evaluation of the novel Presage ST2 assay for the determination of sST2 in human plasma.
METHODS: We evaluated precision and linearity of the assay, analyte stability, and biological variability, determined reference values, performed a method comparison with an established ELISA, and quantified sST2 concentrations in various diseases.
RESULTS: Within-run and total coefficients of variation were <2.5% and <4.0%. The method was linear across the whole measurement range of the assay. The analyte was stable for 48 h at room temperature, for 7 days at 4 degrees C, and for at least 2 months at -20 degrees C and -80 degrees C. The reference change value for healthy individuals was 30%. Age-independent reference values were 3-28 U/mL in males, and 2-16 U/mL in females. The method comparison revealed a high proportional bias. sST2 plasma concentrations were increased modestly in heart failure and moderately in pneumonia and chronic obstructive pulmonary disease. Patients with sepsis exhibited highly elevated sST2 values. In patients with chronic renal disease, however, there was no difference compared to healthy individuals.
CONCLUSION: The Presage ST2 assay meets the needs of quality specifications of laboratory medicine. The results of the clinical assay evaluation are novel with respect to sST2 in various diseases and should initiate further studies.