Analytical performance evaluation of the i-STAT Total β-human chorionic gonadotropin immunoassay

Background: The ability to perform quantitative hCG testing in whole blood at the point-of-care is desirable. The purpose of this study was to perform an analytical validation of the Abbott i-STAT Total beta-hCG test. Methods: Whole blood, plasma, and serum samples were prepared by the addition of hCG and were used to evaluate precision, linearity, analytical sensitivity, accuracy, the high-dose hook effect, and dilution recovery. Results: Imprecision was highest with whole blood (CV = 16.0% and 6.7% at 10 and 1184 IU/l, respectively) and lowest in serum (CV = 8.1% and 4.3% at 11 and 1305 IU/l, respectively). The limits-of-quantitation were 8 and <5 IU/l for whole blood and both plasma and serum, respectively. The assay was linear between 5 and 2000 IU/l in all sample types (R-2 >= 0.998). i-STAT results agreed most closely with the Architect Total beta-hCG assay and with greater differences observed with Beckman Dxl Total beta hCG and Roche Cobas e601 hCG + beta assays (mean differences across all sample types were 9.3% and 12.3%, respectively). A high-dose hook effect was observed at concentrations >400,000 IU/l. Accuracy was achieved in samples diluted with serum but not saline. Conclusions: The i-STAT Total beta-hCG test demonstrates acceptable performance for quantifying hCG in whole blood, plasma and serum. (C) 2015 Elsevier B.V. All rights reserved.