Performance evaluation of the BIOPHEN chromogenic test for Factor XIII activity on the Cobas c502 System

Objective Factor XIII (FXIII) is a protransglutaminase. Upon activation by thrombin and calcium, it acts in the last step of the coagulation cascade leading to fibrin crosslinking and clot stiffness. Acquired FXIII deficiency in critically illed patients, e.g. with trauma, surgery and under ECMO therapy, is not seldom, which needs a prompt laboratory diagnostic. The routine coagulation tests are unable to identify FXIII deficiency. The specific FXIII activity (FXIII:Ac) tests are only available in special coagulation laboratories. This study was aimed to evaluate analytical performance of the BIOPHEN chromogenic test on the Roche Cobas c502 System.

Material and Methods Precision was performed with normal and pathological controls following CLSI EP5-A3. Limit of Blank (LoB), limit of detection (LoD), and limit of quantitation (LoQ) were examined following CLSI EP17-A3. Linearity was performed according to CLSI EP6-A. In addition, patient citrated plasma from routine laboratory were collected and frozen at -80 C until analysis. Each sample was measured with both Berichrom FXIII assay on the Siemens BCS XP and BIOPHEN FXIII assay on Roche Cobas c502. The evaluation of linearity and comparison of patient samples was performed using Validation Manager software (Finbiosoft, Espoo Finland).

Results The intra-assay, inter-assay and between-day coefficient of variation (CV%) were 1.7%, 1.8% and 1.4%, respectively, at the activity of 93% and 3.2%, 1.4% and 2.5%, respectively, at the activity of 39%. LoB, LoB and LoQ values were 2.4%, 2.7% and LoQ 7.0%, respectively. The linear regression equation in the range of 5,5 - 151% was: measured FXIII:Ac = 1.01*expected FXIII:Ac + 0.264 (r = 1). For method comparison, the regression equation according to Passing-Bablok was: FXIII-BIOPHEN Cobas c502 = 1.993*FXIII-Berichrom BCS XP – 3.56 (r = 0.95). Significant discrepant results between two methods were observed in 5 samples with Lipaemia-index ranged between 64 - 160, implying an interference susceptibility of the test on the Cobas C502 to lipaemia. This should be further clarified with more samples.

Conclusion Our results demonstrated acceptable analytical performance of the BIOPHEN chromogenic FXIII:Ac test on the Roche Cobas c502 system, which makes the 24 hour a day available measurement of FXIII:Ac in an emergency laboratory possible.

Publication History

Article published online:
18 June 2021