Abstract Number: PB1175
Meeting: ISTH 2022 Congress
Background: In Norway, patients with haemophilia are provided centralized care at Oslo University Hospital and are registered in the national haemophilia registry. The current standard of care for moderate and severe HB patients is prophylaxis with factor IX (FIX).
Aims: To use real-world data to evaluate treatment outcomes in prophylactically treated HB patients switching from standard half-life (SHL) FIX to extended half-life rFIXFc and report long-term experience of rFIXFc treatment.
Methods: Prospective cohort study of treatment outcomes in moderate and severe HB patients switching from SHL FIX to rFIXFc treated prophylactically pre-and post-switch for ≥12 months. Longitudinal analysis of ongoing rFIXFc prophylaxis over 3 years.
Results: No patients had detectable inhibitors during 365 days before inclusion or developed inhibitors at data cut-off (January 26, 2022). Mean (SD) age of the switch cohort (n=11) was 38.1 (20.9) years and 72.7% had severe HB. Median (IQR) follow-up time was 392.0 (365.0-582.3) days on SHL FIX and 1415.0 (1319.2-1537.2) days on rFIXFc. Median (IQR) prescribed prophylactic dose decreased by 39.5% from 42.3 (36.7-74.4) to 25.6 (23.5-29.4) IU/kg/week after switching from SHL FIX to rFIXFc; median (IQR) number of injections/week decreased from 2.5 (2.0-3.0) to 0.7 (0.7-1.0); median (IQR) annualized bleeding rate was 0.0 (0.0-1.0) before and 0.0 (0.0-0.0) after switch (Table 1).
For the cohort of rFIXFc patients followed over 3 years, median (IQR) prescribed prophylactic dose was 34.9 (20.9-38.9) IU/kg/week and median (IQR) injection frequency/week was 1.0 (0.7-1.0) after 3 years (n=12). Overall, 52.9% of rFIXFc patients experienced zero spontaneous bleedings after 1 year (n=17) versus 91.7% after 3 years (n=12) (Table 2).
Conclusion(s): Norwegian real-world data suggest that HB patients on prophylaxis switching from SHL FIX to rFIXFc reduced factor consumption and injection frequency with a similar level of bleeding outcomes. Prophylactic treatment with rFIXFc resulted in high levels of bleed protection over 3 years.
To cite this abstract in AMA style:Holme P, Glosli H, Thanner J, Sennfält K. Norwegian Real-World Experience with recombinant factor IX Fc (rFIXFc) in Haemophilia B (HB) Patients [abstract]. https://abstracts.isth.org/abstract/norwegian-real-world-experience-with-recombinant-factor-ix-fc-rfixfc-in-haemophilia-b-hb-patients/. Accessed September 27, 2023.
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