PB1226 - Acquired haemophilia A in Finland: a nationwide study of incidence, treatment and outcomes

Background: Acquired haemophilia A (AHA) is a bleeding disorder caused by autoantibody development against FVIII. The incidence and outcomes of AHA have not been studied in nationwide cohort studies recently.

Aims: To determine the incidence, clinical characteristics and outcomes of AHA in Finland.

Methods: This retrospective observational cohort comprised all cases diagnosed with AHA in Finland in 2006-2019. Patients were identified by Finnish Red Cross and HUSLAB laboratory services, the only laboratories that perform FVIII antibody testing in Finland. With national study permit, clinical details were collected from medical charts from all the hospitals and health care units where patients were treated. This study was performed in conjunction with AHA in the Nordics study.

Results: The incidence of AHA was median 0.65 per million per year (range 0.19-1.27). There were 55 patients identified, with median age of 76 years and an even sex ratio with 51% women. When diagnosed, all had bleeding symptoms with severe bleeding in 92%, and 76% received hemostatic therapy. Altogether 92 bleeding episodes were managed with hemostatic therapy, mainly APCC (79%) and rFVIIa (18%). Immunosuppressive therapy was started in 98% of the cases: first-line treatment was steroid monotherapy in 31%, steroids/azathioprine in 29%, steroid/cyclophosphamide in 22%, and rituximab-based regimen in 16%. Median follow-up time was 1.9 years, and all who were alive at data collection were observed at least 2 years after the diagnosis. Complete remission was achieved in 71% of cases and 15% had a relapse. Mortality for bleeds was 13% and for treatment related infections 9%. Overall mortality was 36% one year and 47% two years after the diagnosis.

Conclusion(s): In a nationwide population-based cohort study, we discovered a lower incidence for AHA than previously reported at 0.65 per million per year. Overall mortality among patients with AHA was high, highlighting the frailty of these elderly patients with comorbidities.