Factor Xa-Based Antithrombin Assay Evaluated

A recently introduced antithrombin assay based on Factor Xa (FXa) has been evaluated on four different analyzers.

The INNOVANCE Antithrombin test is a new FXa-based chromogenic assay for automated quantification of functionally active anti-thrombin (AT) on coagulation analyzers.

Scientists working at Siemens Healthcare Diagnostic Products GmbH (Marburg, Germany) collaborated with investigators from the UK, Italy and another institution in Germany. They used clinical surplus plasma samples from 225 patients and 151 apparently healthy individuals from four different study sites to assay antithrombin.

The Siemens' INNOVANCE Antithrombin assay demonstrated on all analyzers repeatability coefficients of variation (CVs) ≤ 3.2% and within-device and between-run CVs ≤ 6.9%. The reference intervals of all analyzers are comparable with 2.5th percentiles between 80% and 85% of normal. The Siemens' INNOVANCE Antithrombin and the Factor IIa-based BerichromAT III (A) methods demonstrated good concordance with very high correlation coefficients.

The INNOVANCE Antithrombin method exhibited an excellent comparability with the STA Antithrombin III assay (Diagnostica Stago; Asnières sur Seine, France) and an acceptable comparability with the Coamatic LR Antithrombin assay (Instrumentation Laboratory, Bedford, MA, USA). The 31 patients with congenital deficiency were identified with all assays except for the patients carrying the P41L heparin-binding site mutation, which was only identified with the INNOVANCE Antithrombin and the STA Antithrombin III methods.

The authors concluded that this multicenter study demonstrates that the INNOVANCE antithrombin assay is precise and reliable to aid in the diagnosis of antithrombin deficiency. The advantages of this assay compared to the other methods were the higher sensitivity for heparin-binding site mutations, the liquid ready-to-use reagents, and the absence of interference by direct thrombin inhibitors. The study was published in October 2011, in the journal International Journal of Laboratory Hematology.

Related Links:
Siemens Healthcare Diagnostic Products
Diagnostica Stago
Instrumentation Laboratory