PO039 | CLINICAL AND LABORATORY CHARACTERISTICS OF ACQUIRED HEMOPHILIA A: PRELIMINARY RESULTS FROM A RETROSPECTIVE OBSERVATIONAL MONOCENTRIC STUDY

S. Suardi¹, M. Bodini², A.C. Giuffrida², A. Zanzanelli³, S. Moruzzi¹, L. Delfino¹, F. Pizzolo¹, S. Genesini², M. Cantini², C. Spillere¹, L. Panepinto¹, F. Zoccatelli¹, E. Malloggi¹, F. Presa¹, A. Moschella¹, M. Merlo¹, G. Gandini², S. Friso¹, N. Martinelli¹ | ¹Department of Medicine, Unit of Internal Medicine B, Azienda Ospedaliera Universitaria Integrata di Verona, Italy; ²Department of Transfusion Medicine, Hemophilia Center, Azienda Ospedaliera Universitaria Integrata di Verona, Italy; ³Division of Internal Medicine, IRCCS Azienda Ospedaliero Universitaria Bologna, Italy

Background. Acquired hemophilia A (AHA) is a rare autoimmune disorder, characterized by the development of autoantibodies directed against coagulation factor VIII (FVIII), thereby leading to a severe bleeding diathesis. Clinical suspicion and understanding of AHA's features are essential for its effective diagnosis and management.
Aims. To describe the clinical characteristics of AHA patients in a monocentric cohort.
Methods. We conducted a retrospective observational study on a cohort of 39 patients with diagnosis of AHA between 2008 and 2025 at the Hospital of Verona, Italy.
Results. This study included 39 patients (males n=19/49%). The age at diagnosis ranged from 41 to 96 years with a mean age of 77 years. Fifteen subjects (38%) were classified as idiopathic AHA. Malignancy was the most frequent underlying condition in 14 subjects (36%), with 6 cases of cancer of the genitourinary tract, 4 cases of cancer of the gastrointestinal tract, 3 cases of breast cancer, and 1 case of brain tumor. Seven subjects (18%) had concomitant autoimmune disorders. Only one case of postpartum AHA was identified, along with single cases linked to with dermatological disease (bullous pemphigoid) or recent drug administration (clopidogrel). The great majority of patients (n=36/92%) had bleeding at diagnosis. The most frequent hemorrhages involved the mucocutaneous district (n=31/79.4%) and the genitourinary tract (n=4/10%). Only 3 patients (8%) had no significant bleeding and were diagnosed based on the laboratory coagulation tests. The mean hemoglobin level was 8.9±3.8 g/dL and the mean platelet count was 235.000±109.000/mcL. The mean aPTT ratio was 2.64±0.92. The mean FVIII activity level was 5.1±7.7%, with 12 subjects (31%) with FVIII activity <1% and 18 subjects (46%) with FVIII activity 1-5%. The inhibitor titer was 47.1±39.2 Bethesda Units (BU). More than half of the patients (n=22/56%) had a high inhibitor titer (>5 BU).
Conclusions. The data from our cohort align with the existing medical literature. AHA should be suspected especially in the elderly population, either males or females, when there are novel and severe bleeding associated with anotherwise unexplained prolonged aPTT. The development of large registries for AHA could allow for better understanding of this rare and sometimes underdiagnosed disease.