Analytical and Clinical Evaluation of the NOWDiagnostics ADEXUSDx Human Chorionic Gonadotropin Test Using Whole Blood

Abstract

Background: Point-of-care (POC) urine qualitative human chorionic gonadotropin (hCG) devices are used to rapidly assess pregnancy status, but many of these devices are susceptible to false-negative results caused by increased concentrations of hCG β core fragment (hCGβcf) that does not contain hCGβcf. Methods: Purified hCG was added to hCG-negative heparinized whole blood to generate samples with known hCG concentrations, and the resulting samples were used to evaluate device sensitivity, low-end reproducibility, high-dose hook effect, intermediate range performance, acceptable sample volume, acceptable hematocrit range, and lot-to-lot variation. Device performance was also prospectively evaluated in 40 pregnant and 40 nonpregnant women aged 18-44 years in a hospital-based clinic or an academic hospital emergency department. Results: All device observations were positive using a whole blood sample containing a plasma hCG concentration of 2.2 × 106 IU/L, and all device observations were positive from18 IU/L to 1.2 × 103 IU/L and from 2.5 × 104 IU/L to 2.2 × 106 IU/L. Three invalid results were observed in the intermediate range because of decreased control line intensity. The minimum sample volume was 30 μL, and maximum hematocrit was 46%. In 40 pregnant and 40 nonpregnant women aged 18-44 years, the device generated 100% concordance with urine qualitative and plasma quantitative test results. Conclusions: The ADEXUSDx™ hCG test demonstrates acceptable performance for the determination of pregnancy status using capillary fingerstick samples.