New Biological Tests in Patients With Antiphospholipid Antibodies

Study Overview
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Brief Summary
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Antiphospholipid syndrome (APS) is an autoimmune disease characterized by thromboembolic events or pregnancy complications associated with circulating antiphospholipid antibodies (aPL-Abs). APS diagnosis needs the presence of both clinical and serological criteria (SAPORRO criteria, updated with Sydney criteria in 2006). However, no correlation between laboratory assays and the clinical thrombosis risk in patients with aPL-Abs was observed as only few patients with aPL-Abs developed clinical manifestations. Thrombin generation assays (TGA) is a global coagulation test that may represent a certain interest to evaluate thrombosis risk as a high thrombin generation capacity seems to be an independent risk factor for recurrent thromboembolic events. Another point of interest to assess the thrombotic risk is the detection of autoantibodies recognizing domain 1 of β2Gp1 (aβ2GP1-dm1). These autoantibodies are strongly related correlated with thrombotic and pregnancy manifestations. Recently, a commercial chemiluminescence immunoassay (CLIA) for detection of aβ2GP1-dm1 became available on Acustar® analyzer (HemosIL Acustar®, Instrument Laboratory, Bedford, USA) to facilitate aβ2GP1-dm1 research. The aim of this study is to evaluate two additional laboratory assays to improve the correlation between laboratory assays and the clinical thrombosis risk in patients with antiphospholipid (APL): thrombin generation assay and aβ2GP1-dm1. Each biological result (Antibodies to Domain 1 (Dm1) of β2-Glycoprotein 1 (aβ2GP1-dm1) and Thrombin Generation Test (TGT) parameters: endogen thrombin potential (ETP), lag time and time to peak) will be compared to the history of clinical thrombosis (venous or arterial thrombosis and/or obstetrical complications such as defined by the Saporro criteria updated with Sydney criteria in 2006) for each patient.

Official Title
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Domain 1 of β2-Glycoprotein 1 Autoantibodies and Thrombin Generation Capacity in Patients With Antiphospholipid Antibodies

Conditions
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Antiphospholipid Syndrome

Intervention / Treatment
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* Biological: blood sample


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Adult patients with confirmed aPL-Abs (at least two positive determinations at least 12 week apart) Subject non opposition Exclusion Criteria: Age < 18 years Patient under the protection of justice, under guardianship or under curatorship Patient with anticoagulant treatment, except heparin Clinically symptomatic liver disease, supported by e.g. diagnosis of cirrhosis, portal hypertension, ascites, PT superior or egal to 5 seconds above upper normal limit Platelet count < 100 G/L (giga/liter) Poor venous access Non confirmed suspicion of APS

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Biological APS<br>50 Asymptomatic patients with aPL antibodies and prolonged APTT | Biological: blood sample<br>* A single 15 mL blood draw is planned for this study, as follow: 10 mL citrated tube (2 tubes) for APTT, PT, D-Dimers, LA, aCL, aβ2GP1, aβ2GP1-dm1 and TGA 5 mL EDTA tube for blood count During a follow up visit, a 5 ml citrated tube and a 5 mL EDTA tube are collected from each patient for their routine laboratory evaluation. One additional citrated tube will be required to measure thrombin generation and aβ2GP1-dm1.<br>|
| Obstetrical APS<br>50 patients with Obstetrical aPL syndrome | Biological: blood sample<br>* A single 15 mL blood draw is planned for this study, as follow: 10 mL citrated tube (2 tubes) for APTT, PT, D-Dimers, LA, aCL, aβ2GP1, aβ2GP1-dm1 and TGA 5 mL EDTA tube for blood count During a follow up visit, a 5 ml citrated tube and a 5 mL EDTA tube are collected from each patient for their routine laboratory evaluation. One additional citrated tube will be required to measure thrombin generation and aβ2GP1-dm1.<br>|
| Thrombosis APS<br>APS with a personal history of venous or arterial thrombosis (50 patients) | Biological: blood sample<br>* A single 15 mL blood draw is planned for this study, as follow: 10 mL citrated tube (2 tubes) for APTT, PT, D-Dimers, LA, aCL, aβ2GP1, aβ2GP1-dm1 and TGA 5 mL EDTA tube for blood count During a follow up visit, a 5 ml citrated tube and a 5 mL EDTA tube are collected from each patient for their routine laboratory evaluation. One additional citrated tube will be required to measure thrombin generation and aβ2GP1-dm1.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| aβ2GP1-dm | The hypercoagulability status will be compared in each group. Each biological result of aβ2GP1-dm1 will be compared to a gold standard: the history of clinical thrombosis (venous or arterial thrombosis and/or obstetrical complications such as defined by the Saporro criteria updated with Sydney criteria in 2006) for each patient. | One day | 
| Endogenous Thrombin Potential (ETP) | The hypercoagulability status will be compared in each group. Each biological result of ETP will be compared to a gold standard: the history of clinical thrombosis (venous or arterial thrombosis and/or obstetrical complications such as defined by the Saporro criteria updated with Sydney criteria in 2006) for each patient. | One day | 
| peak of thrombin | The hypercoagulability status will be compared in each group. Each biological result of peak of thrombin will be compared to a gold standard: the history of clinical thrombosis (venous or arterial thrombosis and/or obstetrical complications such as defined by the Saporro criteria updated with Sydney criteria in 2006) for each patient. | One day | 
| lag time | The hypercoagulability status will be compared in each group. Each biological result of lag time will be compared to a gold standard: the history of clinical thrombosis (venous or arterial thrombosis and/or obstetrical complications such as defined by the Saporro criteria updated with Sydney criteria in 2006) for each patient. | One day | 
| time to peak | The hypercoagulability status will be compared in each group. Each biological result of time to peak will be compared to a gold standard: the history of clinical thrombosis (venous or arterial thrombosis and/or obstetrical complications such as defined by the Saporro criteria updated with Sydney criteria in 2006) for each patient. | One day |