PB1131 - Clinical performance evaluation of the new Stago system for prothrombin time determination: sthemO PT assay on sthemO 301 analyzer

Background: Prothrombin time (PT) is essential in the routine hemostasis tests panel to explore the extrinsic and common coagulation pathways and monitor VKA therapy. To face future challenges, a new Medium-High throughput analyzer, sthemO 301, was developed with dedicated reagents such as the sthemO PT. However, to ensure proper patients medical care continuity, the results consistency results between sthemO and STA systems is compulsory to validate sthemO 301 solution.

Aims: To prove the clinical performances of sthemO PT on sthemO 301 by demonstrating the correlation to the STA®-NeoPTimal on STA-R Max® on sec, % and INR units.

Methods: A total of 333 samples were included on three sites for PT comparison (all reagents and analyzers from Stago, France). The sample set consisted in plasma samples obtained from patients categorized as normal, under VKA, bridging anticoagulant therapy or heparin treatment, with extrinsic factor(s) deficiency or with liver failure.
The ISI used for INR determination were provided by the manufacturer (i.e. 0.98 for sthemO PT and 1.04 for STA® - NeoPTimal) while the mean normal prothrombin times (MNPT) were determined per site and per system with minimum 20 fresh samples from healthy patients.

Results: SthemO PT MNPT calculated for GHBS Lorient, Cerba Xpert and Medibio laboratories were 12.6 sec, 11.8 sec and 12.1 sec and with STA®-NeoPTimal 13.6 sec, 13.5 sec and 13.2 sec.
Passing-Bablok regression analysis was performed to evaluate correlation by pooling results of all sites. Displayed in Figure 1 and Table 1 are slope, intercept, Pearson correlation coefficient of those regressions and bias calculated on value of clinical interest (normal value and INR therapeutic range).

Conclusion(s): sthemO PT on sthemO 301 comparison to STA®-NeoPTimal on STA-R Max® reached all acceptance criteria. The consistency of results between the two systems demonstrate their substantial equivalence. Therefore the intended purpose of sthemO PT is validated.