Efficacy of Prolonged Anticoagulation for Primary Prevention of Venous Thromboembolic Disease in Autoimmune Hemolytic Anemia: a Prospective, Phase II, Randomized, Multicenter Study

Inclusion Criteria:

• Patient aged ≥ 18 years

• Patient with a diagnosis of primary or secondary autoimmune hemolytic anemia (AIHA) (infections, hematologic diseases, systemic diseases), according to the followingcriteria:

• Hemoglobin <12 g/dL

• and decreased haptoglobin (<0.4 g/L)

• and positive direct antiglobulin test (direct Coombs test) (IgG +/- C3d)

• Patient newly diagnosed or relapse

• Patient with an estimated life expectancy of more than 6 months

• Patient who provided free, written and informed consent

Exclusion Criteria:

• Patients with immediate symptomatic VTE, confirmed by appropriate complementaryexaminations (venous Doppler of the lower limbs, thoracic angioscanner or pulmonaryscintigraphy).

• Patients on curative anticoagulation (venous thromboembolic disease, atrialfibrillation)

• Patient on dual antiaggregation treatment

• Patient with active bleeding

• Patient with a known condition or lesion at risk of bleeding

• Patient with ischemic stroke with hemorrhagic transformation within 6 months priorto inclusion

• Patient on preventive anticoagulation for 14 days or more

• Patient with a contraindication to apixaban:

• Known hypersensitivity to the molecule or to any of the excipients,,

• thrombocytopenia <100 G/L,

• kidney failure (glomerular filtration rate < 30 ml/min/1.73m²)

• Active liver disease (liver failure defined as Factor V <50% or INR >1.5, ALTelevation >2 times the upper limit of normal)

• Patients receiving concomitant CYP3A4 inducers (rifampin, phenytoin, carbamazepine,phenobarbital, St. John's Wort) or CYP3A4 inhibitors (azole antifungals, HIVprotease inhibitors), if these therapies cannot be discontinued or modified

• Patients with a contraindication to enoxaparin:

• allergy to the drug

• history of heparin-induced thrombocytopenia

• Patient with cold agglutinin-related AHAI (C3d-positive ADT alone withidentification of cold agglutinins)

• Patient with severe disorders of hemostasis:

• hypofibrinogenemia < 2 g/L,

• disseminated intravascular coagulation (APTT prolongation>1.2, and PT<50%, andthrombocytopenia<100 G/L, and D-Dimer >500 µg/L)

• hemophilia

• Patient whose clinical condition requires hospitalization in an intensive care unit

• Patient who has already participated in the study

• Patient not affiliated to national health insurance

• Patient under legal protection (curatorship, guardianship)

• Patient subject to a measure of legal protection

• Pregnant, parturient or breastfeeding women

• Patient with physiological capacity to procreate (having had her first menstrualperiod and not menopausal and not presenting permanent sterility (hysterectomy,bilateral salpingectomy, bilateral oophorectomy)) and unable to have effectivecontraception (i.e., provided by an estrogen-progestin oral contraceptive orprogestogen, a contraceptive implant, an intrauterine device or a tubal ligation)

• Patient of legal age who is unable to provide consent