Acquired haemophilia A: A 15‐year population‐based review of incidence rate, patient demographics and treatment outcomes

Abstract

AbstractIntroductionAcquired haemophilia A (AHA) is a rare bleeding disorder characterized by autoantibodies against coagulation factor VIII (FVIII). Estimates of AHA incidence are largely based on registry data, which may be prone to referral bias. Population‐based studies can enhance our understanding of the epidemiology, presentation and outcomes of AHA.MethodsWe conducted a retrospective, population‐based cohort study of all AHA diagnosed and treated in Manitoba, Canada over a 15‐year period. Using records from the sole provincial reference laboratory, we identified all patients with FVIII inhibitors who did not have congenital haemophilia.  Using a piloted case report form, patient data was ascertained from hospital and bleeding disorder clinic records.ResultsFrom 2006 to 2021, we identified 34 patients with AHA, corresponding to a population‐based incidence rate of AHA of 1.78 cases per million per year. The median age at presentation was 76 years and most cases were idiopathic (79%). Almost all patients (97%) presented with bleeding, of which 58% were considered major bleeds and required haemostatic agents in 67%. Longstanding unexplained bleeding symptoms were commonly reported, suggesting delayed diagnosis. Immunosuppressive therapy (IST) was administered in 88% of patients. Remission was achieved in 79% of patients; median time to remission was 2.1 months. There were two deaths due to bleeding. No deaths due to IST were reported.ConclusionThe population‐based incidence of AHA in Manitoba is 1.78 cases/million/year. Bleeding is common and can be life‐threatening. AHA outcomes are encouraging with the use of haemostatic agents and IST. Serious treatment‐associated morbidity and mortality is uncommon.