Abstract Number: PB1931
Meeting: ISTH 2020 Congress
Background: The lupus anticoagulant (LA) is classified as an antibody that is recognized in antiphospholipid syndrome (APS). Mixing plasma LA test improves the discrimination of LA in presence of an inhibitor or in deficiencies of a coagulation factor, as is the case in patients receiving vitamin K antagonists(VKAs).
Aims: The objective of this study is to review the experience over the LA tests in a our hospital.
Methods: Cross-sectional study performed from January 2018 to December of 2019 in patients with an INR above 1,5 in who a study for detection of LA was required.
Results: Samples from 68 men and 65 women were analyzed. 44 patients was diagnosis of venous thromboembolic 12 patients arterial thrombosis, the remaining 69 patients had non-thrombotic conditions.
A total of 86 samples had an INR between 1,5-3. In these patients a complete study was carried out for the detection of AL. Out of 125 samples, 39 presented an INR >3, and confirmatory AL study was not performed. In 86 remaining samples with INR between 1,5 and 3 was ordered a confirmatory AL study in a sample mixed 1:1 (patient plasma/normal plasma) using dRVVT and SCT (screen-confirm- ratio mixing) (IL instruments®). Out of 86 samples, 55 had a positive mixing test for LA and 26 were positive for both dRVVT and SCT tests (screen-confirm mixing) (IL instruments®). The 55 patients with samples with a positive LA mixing test, 11 patients were diagnosed of APS. (Table 1)
Conclusions: The use of dRVVT and SCT assays reports clearer results of laboratory determination of LA. In samples with INR between 1,5-3 using a AL study in a sample mixed 1:1 using dRVVT and SCT (screen-confirm- ratio mixing) can be a useful tool. In samples with INR above of 3,0 should be mandatory to perform new LA tests beyond the treatment with anticoagulants.
|Test||Number of patients||APS|
|dVVRT (-) SCT (-) 1||31||1|
|dVVRT (+) SCT (-)||29||1|
|dVVRT (+) SCT (+)||26||10|
[Table 1. Correlation between test and diagnosis]
To cite this abstract in AMA style:Pinzon Mariño S, Garcia Ortego AJ, Gomez Martinez A, Martin-Consuegra Ramos S, Hernandez Mata CF, Moreno Carbonell M, Gonzalez Gomez E, Bakali Badesa S, Latorre P, Fernandez Mosteirin N, Calvo Villas JM. Mixing Studies in Lupus Anticoagulant Tests: A Useful Tool at the Time of Analysis [abstract]. Res Pract Thromb Haemost. 2020; 4 (Suppl 1). https://abstracts.isth.org/abstract/mixing-studies-in-lupus-anticoagulant-tests-a-useful-tool-at-the-time-of-analysis/. Accessed December 10, 2023.
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