Acquired haemophilia A (AHA; 2017 ICD-10-CM: D68.311) is a rare but potentially life-threatening systemic autoimmune disorder. Acquired haemophilia is most commonly attributable to autoantibodies toward endogenous coagulation factor (F) VIII (AHA), however autoantibodies to a number of other coagulation factors, including I, II, V, VII, IX X, XI, and XIII, have also been described.1
The disorder is often diagnosed following sudden or unexpected bleeding symptoms in persons with no family or personal history of a bleeding disorder. Patients often present to physicians with little or no experience with the management of haemostatic disorders. Lack of awareness of the disorder may lead to an incorrect or delayed diagnosis and suboptimal treatment, therefore if AHA is suspected, immediate consultation with a haemophilia centre experienced in the management of inhibitory antibodies is recommended to ensure a rapid and accurate diagnosis, timely treatment and avoid additional bleeding risk associated with inappropriate interventions. 2,3
The incidence of AHA has been estimated to be approximately 1.5 patients per million population per year.4 Other underlying medical conditions, including other autoimmune disorders, various malignancies, use of certain medications and pregnancy, can be identified in approximately half of the patients diagnosed with AHA; the remaining cases are classified as idiopathic.3 AHA can develop at any age in both genders. Older individuals are typically affected, with the exception of a peak among women between the ages of approximately 20–40 years which is primarily attributable to post-partum inhibitors.5 Reported mortality estimates range from approximately 3–40%, although some older reports may include patients with limited access to effective treatment.4-7
The bleeding pattern associated with AHA is different than that observed in congenital haemophilia A (HA) or B (HB), including bruising and bleeding into soft tissues, muscles and mucosae, gastrointestinal, intracranial, retropharyngeal, retroperitoneal and surgical bleeding. Haemarthroses are uncommon.
Bleeding may be severe and potentially life-threatening in >70% of cases,5 however 30% of cases present as mild bleeding and may require no haemostatic treatment.4,6 Ecchymosis and subcutaneous haematomas, for example, even if extensive, may require only close observation but no specific treatment.8
Severity of bleeding and bleeding risk do not correlate well with the FVIII activity level or with inhibitor titre.2,9 Patients remain at risk of spontaneous, life-threatening bleeding while the inhibitory alloantibody persists, even if the initial presentation is associated with mild or no bleeding.2,8 In contrast to inhibitory alloantibodies that may develop in response to factor replacement therapy in patients with congenital HA or HB, the autoantibodies associated with AHA show type 2 kinetics and some residual FVIII activity may be detectable.
1. Franchini M, Lippi G, Favaloro EJ. Acquired inhibitors of coagulation factors: part II. Semin Thromb Hemost 2012;38:447-53.
2. Collins P, Baudo F, Huth-Kuhne A, et al. Consensus recommendations for the diagnosis and treatment of acquired hemophilia A. BMC Res Notes 2010;3:161.
3. Franchini M, Castaman G, Coppola A, et al. Acquired inhibitors of clotting factors: AICE recommendations for diagnosis and management. Blood Transfus 2015;13:498-513.
4. Collins PW, Hirsch S, Baglin TP, et al. Acquired hemophilia A in the United Kingdom: a 2-year national surveillance study by the United Kingdom Haemophilia Centre Doctors' Organisation. Blood 2007;109:1870-7.
5. Knoebl P, Marco P, Baudo F, et al. Demographic and clinical data in acquired hemophilia A: results from the European Acquired Haemophilia Registry (EACH2). J Thromb Haemost 2012;10:622-31.
6. Baudo F, Collins P, Huth-Kühne A, et al. Management of bleeding in acquired hemophilia A: Results from the European Acquired Haemophilia (EACH2) registry. Blood 2012;120:39-46.
7. Tengborn L, Baudo F, Huth-Kuhne A, et al. Pregnancy-associated acquired haemophilia A: results from the European Acquired Haemophilia (EACH2) registry. BJOG 2012;119:1529-37.
8. Huth-Kuhne A, Baudo F, Collins P, et al. International recommendations on the diagnosis and treatment of patients with acquired hemophilia A. Haematologica 2009;94:566-75.
9. Baudo F, de Cataldo F. Acquired haemophilia in the elderly. In: Balducci L, Ershler W, de Gaetano G, eds. Blood Disorders in the Elderly. Cambridge: Cambridge University Press; 2007:389-407.