Acquired haemophilia A; D68.38;

Acquired hemophilia A (AHA) is a rare bleeding disorder caused by the spontaneous formation of inhibitory autoantibodies against coagulation factor VIII (FVIII), less frequently against FIX.

AHA has a low incidence of about 1.5 cases per million people. The occurrence of AHA is found in up to 15% of cases of hemophilia A, mostly in severe hemophilia. The risk is highest for the mutation type with large deletions of several domains.

AHA is a disease that is most frequently observed in older people (average age 64-78 years), but also in children and in the postpartum period.

Delayed or absent hemostasis despite substitution of factor VIII. Possible extensive (non-petechial bleeding) bleeding, muscle bleeding, joint bleeding.

Treatment should only take place in hemophilia centers:

Treatment has three aims:

• Stop the bleeding
• Prevent further bleeding by eliminating the inhibitor and the clone responsible for its production
• Treat the underlying cause, if identified

The speed and appropriateness of treatment and management are crucial. For bleeding events, treatment is primarily aimed at controlling the acute bleed quickly and eliminating the inhibitor to minimize the risk of rebleeding, which remains in the presence of the anti-FVIII inhibitor. While treatment of acute bleeding is an important priority in AHA care, not all patients bleed and not all bleeds require intervention.

Patients with severe bleeding and a drop in hemoglobin levels require immediate hemostatic treatment. Patients with mild/moderate bleeding without a significant drop in hemoglobin levels may not require immediate hemostatic therapy. However, they may develop severe bleeding at any time and therefore need to be monitored closely. Patients at high risk of bleeding (recent surgery, recent delivery, etc.) require prophylactic hemostatic therapy. The introduction of bypass agents such as activated prothrombin complex concentrates (aPCC) (factor VIII inhibitor bypass activity (FEIBA), administered at a dose of 50-100 U/kg every 8-12 hours with a maximum dose of 200 U/kg/24 hours); recombinant activated factor VII (rFVIIa, NovoSeven, at a dose of 90-120 μg/kg every 2-3 hours) and, more recently, FVIII porcine at a starting dose of 200 IU/kg has significantly improved the treatment of acute bleeding (Zanon E 2023) .

In the case of high-titer alloantibodies, causal therapy of the inhibitor should be carried out by creating immune tolerance by means of high-dose factor administration (immune tolerance therapy, in the case of inhibitor hemophilia B in combination with immunomodulating therapy). In the case of autoantibodies, immunosuppressive therapy (e.g. prednisolone, cyclophosphamide, rituximab) is indicated to eradicate the antibody.

Risk of infection and AHA: In the past, many hemophilia patients were infected with HBV, HCV and HIV through F. VIII preparations and blood transfusions. The risk of transmission of pathogenic viruses (e.g. HIV, HSV, EBV, CMV, HBV, HCV) should not exist with highly purified and virus-inactivated factor concentrates and is excluded when recombinant factor preparations are used. Vaccinate all patients against hepatitis B!

Genetic counseling: All patients with hereditary haemorrhagic diathesis are given genetic counseling + family examination.

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