PB0367 - Determining Thrombogenicity: Using a Modified Thrombin Generation Assay to Detect the Level of Thrombotic Event Risk in Lupus Anticoagulant-Positive Patients

Sunday, June 23, 2024

13:45 – 14:45 ICT

Room: Exhibition Hall

Presenting Author(s)

Pavla Bradáčová, PhD student

Head of laboratory
Department of Hematology, Masarykova nemocnice v Ústí nad Labem
Ústí nad Labem, Ustecky kraj, Czech Republic

Co-Author(s)

LS

Luděk Slavík

Scientist
Faculty of Medicine and Dentistry, Palacky University Olomouc
Olomouc, Olomoucky kraj, Czech Republic
J�

Jana Úlehlová

Bioanalyst
Department of Hemato-Oncology, University Hospital Olomouc, Faculty of Medicine and Dentistry, Palacky University Olomouc
Olomouc, Olomoucky kraj, Czech Republic
JU

Jana Ullrychová

Doctor of medicine
Department Clinical Hematology, Masaryk Hospital Ústí nad Labem
Ústí nad Labem, Ustecky kraj, Czech Republic
EJ

Eliška Jará

Bioanalyst
Department Clinical Hematology, Masaryk Hospital Ústí nad Labem
Ústí nad Labem, Ustecky kraj, Czech Republic
JP

Jana Procházková

Doctor of medicine
Department of Hemato-Oncology, University Hospital Olomouc, Faculty of Medicine and Dentistry, Palacky University Olomouc
Olomouc, Olomoucky kraj, Czech Republic
AH

Antonín Hluší

Doctor of medicine
Department of Hemato-Oncology, University Hospital Olomouc, Faculty of Medicine and Dentistry, Palacky University Olomouc,
Olomouc, Olomoucky kraj, Czech Republic

Background: Antiphospholipid syndrome (APS) is a hypercoagulable state accompanied by the presence of heterogeneous antiphospholipid antibodies (aPL) that nonspecifically affect hemostasis. Although they prolong phospholipid-dependent coagulation tests in the laboratory, they are thrombogenic in vivo. One possible theory that explains this paradox is the inhibitory effect of antibodies on the second most potent hemostasis inhibitory system, the activated protein C (APC) system, the elimination of which may manifest as a thrombotic complication.

Aims: The aim of our study was to determine the thrombogenicity of lupus anticoagulant (LA)
antibodies in a group of 85 patients with LA-positive samples with and without clinical manifestations
of APS.

Methods: We used a modified thrombin test (TGA) with the addition of activated protein C (APC). TGA was measured with and without added APC, and then the ratio of the two measurements was evaluated using a cut-off of R ≤ 4.5 (90th percentile).

Results: We compared of the two groups’ TGA results revealed statistically significant differences
(Fisher’s test p = 0.0016). The group of patients (58) exhibiting clinical manifestations of APS showed
higher thrombogenicity in 56.9% of patients, while the group of patients (27) not yet exhibiting clinical manifestations of APS showed higher thrombogenicity in 25.9% of patients. There were no significant differences in the specificity of the TGA test between the groups of patients exhibiting similar clinical manifestations. Receiver operating characteristic curve analysis showed a more significant relationship (p = 0.0060) for TGA than for LA titre (p = 0.3387).

Conclusion(s): These data suggest that the determination of LA thrombogenicity with the TGA assay leads to an increased prediction of the manifestation of a thromboembolic event. Our findings appear to be particularly relevant for the prediction of thrombotic events in patients with laboratory-expressed APS and no clinical manifestations.