Introduction

Acquired hemophilia (AH) is a severe bleeding disorder caused by inhibiting autoantibodies against a coagulation factor, most often factor VIII (FVIII), developing in a patient with no previous history of bleeding. Due to the rarity of acquired hemophilia B, with antibodies formed against FIX, this guideline primarily concerns acquired hemophilia A (AHA).

AHA is a rare disorder and the majority of those affected are elderly, except for the rare cases of pregnancy associated AHA in younger women. The activated partial thromboplastin time is usually prolonged while other laboratory screening tests for hemostasis such as platelet count and prothrombin time are within the normal range. Patients with AHA pose clinical challenges, often being elderly and frail with additional comorbidities. The mortality rate is high (3.3% - 22% in different studies) [1,2] and treatment involves the use of specific and expensive coagulation promoting products. The diagnosis requires identification of autoantibodies (inhibitors) with a specialized test. Consequently, both special laboratory facilities and clinical experience are required to manage this group of patients.

In recent years, valuable information has been collected regarding e.g. incidence, frequency of co-existing disorders, mortality, and bleeds as well as the use of eradication therapy of inhibitors. This information has been gained from several studies including the study by the Nordic Haemophilia Council, published in 2023 [3] (Table 1).

General recommendation

• The physician on duty at a hemophilia center should be consulted.

1.

Collins PW, Hirsch S, Baglin TP, Dolan G, Hanley J, Makris M, et al. Acquired hemophilia A in the United Kingdom: a 2-year national surveillance study by the United Kingdom Haemophilia Centre Doctors’ Organisation. Blood 2006;109:1870–7. doi:10.1182/blood-2006-06-029850.

2.

Knoebl P, Marco P, Baudo F, Ccollins P, Huth-Kühne A, Nemes L, et al. Demographic and clinical data in acquired hemophilia A: results from the European Acquired Haemophilia Registry (EACH2). Journal of Thrombosis and Haemostasis 2012;10:622–31. doi:10.1111/j.1538-7836.2012.04654.x.

3.

Lindahl R, Nummi V, Lehtinen A, Szanto T, Hiltunen L, Olsson A, et al. Acquired Haemophilia A in four north European countries: survey of 181 patients. British Journal of Haematology 2022;201:326–33. doi:10.1111/bjh.18611.