Acquired hemophilia A

Abstract

Acquired inhibitors of coagulation are a group of rare but potentially life-threatening blood disorders characterized by the presence of autoantibodies directed against clotting factor. Autoantibody against factor VIII is the most common form of clotting factor inhibitor, a condition also known as acquired hemophilia A. We present a clinical series of nine patients diagnosed and treated for acquired hemophilia A at our institution. Among these nine patients, there were five men and four women with a median age of 64 years. All patients presented with bleeding diathesis. Factor eight inhibitor bypassing agent and/or recombinant factor VIIa were predominantly used for control of active bleeding. For elimination of autoantibodies, either steroids alone or the combination of steroids with rituximab or oral cyclophosphamide was used. Despite aggressive measures, two of the patients had a poor outcome; seven of the nine patients (77%) had a good clinical outcome. Acquired hemophilia A should be strongly suspected in any patient presenting with bleeding and a prolonged activated partial thromboplastin time. Early initiation of factor bypassing agents such as activated prothrombin complex concentrates or recombinant factor VIIa, along with the use of immunosuppressive agents, can be lifesaving.

Keywords: Acquired hemophilia A; acquired inhibitors of coagulation; activated prothrombin complex concentrates; recombinant factor VIIa.

Figure 1.

An algorithm for an initial approach in a patient with suspected acquired hemophilia A. *The patient’s medication list should be reviewed for the presence of heparin and heparin-like products. If the presence of heparin is suspected in the blood sample, blood should be redrawn from an uncontaminated peripheral vein. The presence of heparin can be confirmed by performing thrombin time and relapsing test. Direct thrombin inhibitors (argatroban, dabigatran) can prolong both activated partial thromboplastin time (aPTT) and prothrombin time (PT) but at low levels may not prolong PT. Direct factor Xa inhibitors can variably prolong PT and aPTT. #Presence of antiphospholipid antibody should be excluded by adding the source of phospholipid. Correcting of mixing study signifies the presence of lupus anticoagulant, which is more likely to be associated with thrombosis than bleeding. HMW indicates high molecular weight.

Figure 2.

Algorithm for the management of acquired hemophilia A (AHA). *In a patient with suspected AHA with major bleeding, the factor bypassing agents activated prothrombin complex concentrates (aPCC) or recombinant factor VIIa (rFVIIa) should be administered while awaiting the inhibitor titer. *Use of factor bypassing agent is always recommended if available or if the patient continues to bleed. ^∧Both factor eight inhibitor bypassing agent (FEIBA) and rFVIIa are considered equally effective. The choice depends on availability and local experience. +Listed is the commonly used regimen. BU indicates Bethesda unit.