Abstract Number: PB0542
Meeting: ISTH 2020 Congress
Background: Deficiencies of the coagulation inhibitors,antithrombin (AT), protein C (PC) and protein S(PS) are associated with an increased risk for venous thromboembolism.Measurement of these markers requires reliable tests for comparability and transferability of results within and between laboratories.
Aims: This work evaluates AT, PC and PS main assay methods state-of-the-art from External Quality Assessment (EQA) results of the program provided by ProBioQual, a french proficiency testing association.
Methods: Participant laboratories (330 for AT,102 for PC ,79 for PS in 2019) received 12 lyophilized human citrated plasmas for AT, 8 for PC and PS, at 3 or 4 different levels for each variable. Statistical evaluation was performed according to the ISO 13528:2015 guideline by applying Robust Algorithm A. The consensus value was calculated for all participants (AP) results and each peer group (PG).The imprecision of methods was evaluated by the inter-laboratory coefficient of variation (CV) for AP and each PG. Accuracy was quantified as median bias (bias50) and 90th percentile bias (bias90) of laboratory results from AP or PG consensus value.
Results: For AT activity, AP CVs increase from 5.6% at normal level to 10.4% at abnormal level; PG and AP bias90 are very close, around 9% at normal level and 16% at low level.
For PC activity, the PG CVs with chronometric assays (9 to 15%) are always higher than PG CVs with chomogenic assays (3 to 6%).
For PS clotting tests, PG and AP bias90 reach respectively 18.5% and 20.2% for a level of 30%. Free PS antigen performance is satisfactory: AP bias90 between 9.3% and 11.5% ,and AP CVs between 6 and 7.5%.
Conclusions: Performance of AT, PC and PS assays depend on the methodology used (clotting,chromogenic,antigenic). Results obtained in EQA surveys can help to define required analytical quality specifications for routine practice.
To cite this abstract in AMA style:
Bon C, Meley R, Lopez M, Sotta C, Eynard J-, Poggi B. Performance of Thrombophilia Markers Assays Evaluated from Results of an External Quality Assessment Program [abstract]. Res Pract Thromb Haemost. 2020; 4 (Suppl 1). https://abstracts.isth.org/abstract/performance-of-thrombophilia-markers-assays-evaluated-from-results-of-an-external-quality-assessment-program/. Accessed October 1, 2023.« Back to ISTH 2020 Congress
ISTH Congress Abstracts - https://abstracts.isth.org/abstract/performance-of-thrombophilia-markers-assays-evaluated-from-results-of-an-external-quality-assessment-program/