PB0958 - Assessment of 3 new functional antithrombin, protein C and protein S assays

Background: Yumizen G1550 is a recently launched fully automated hemostasis analyser. Horiba has developed reagents for thrombophilia screening.

Aims: The aim of the study was to compare the performances of the couple Horiba/Yumizen G1550 with the local configuration (Stago or Hyphen BioMed/STA-R Max) for the measurement of antithrombin, protein C (PC) and protein S (PS).

Methods: All 3 Horiba reagents were functional assays measuring antithrombin, PC and PS activities. Local instrument was the Stago STA-R Max. The following reagents were used for measuring antithrombin and PC activities: STA Stachrom AT III (Stago), HEMOCLOT PC (Hyphen BioMed).
Repeatability was assessed using 2 levels of controls (30 replicates). Reproducibility was estimated after 25 runs of 2 levels of controls. Values of repeatability and reproducibility were previously calculated for the local configuration (repeatability: 10 replicates of plasma sample; reproducibility: 30 runs of control samples).
Passing Bablok and Bland Altman methods were used for the comparison. Of note the local configuration did not allow a comparison for PS measurement (antigenic free PS measured with STA Liatest Free PS-Stago). Agreement between the 2 configurations was assessed using an 80% cut-off for antithrombin deficiency and 70% for PC deficiency.

Results: As compared with the local configuration the Horiba/Yumizen configuration displayed good performances for AT and PC activities (table). Of note PC activity CVs were lower with the Yumizen configuration for both repeatability (4.0 and 1.6% vs 4.2 and 4.0%) and reproducibility (3.9 and 4.6% vs 7.4 and 8.7%). As expected CVs were higher for PS activity than antigenic free PS.
We obtained the following values for correlation:
- Antithrombin: r= 0.96; bias=11%; 1/22 conflicting sample.
- PC: r=0.85; bias=16%; 10/67 (15%) conflicting samples.

Conclusion(s): Horiba reagents showed good performances as compared with local configuration. Although the couple Horiba/Yumizen led to a misclassification in 10/67 samples incorrectly classified as PC deficiencies.