HAEMFIX: Impact of Switching From SHL‐FIX to EHL‐FIX in Patients With Haemophilia B

INTRODUCTION: Haemophilia B is an X-linked recessive bleeding disorder caused by coagulation factor IX (FIX) deficiency. Treatment involves intravenous replacement of FIX. Recently, extended half-life (EHL) FIX products have been introduced alongside standard half-life (SHL) products to optimize therapy. AIM: This study evaluated bleeding rates, joint health, factor consumption, dosage, and health-related quality of life (HRQoL) in patients switching from SHL- to EHL-FIX products, as well as in those exclusively treated with EHL-FIX. METHODS: Retrospective data from the medical records of 37 children with haemophilia B treated between 2010 and 2023 at two German Haemophilia Care Centres were analysed. HRQoL was assessed cross-sectionally using haemophilia-specific and generic questionnaires. RESULTS: Twenty-seven patients (median age: 12 years, range 2-19 years) switched from SHL- to EHL-FIX, while 10 received EHL-FIX from the start of prophylaxis. The mean annual bleeding rate (ABR) improved from 6.01 ± 7.01 (SHL) to 2.85 ± 3.42 (EHL). Factor consumption (159,577.8 ± 99,817.9 IU/year), dosage (118.9 ± 50.3 IU/kg/week) and infusion frequency (145 ± 35.6 infusions/year) decreased after switching (100,247.7 ± 46,268.6 IU/year; 56.4 ± 23.7 IU/kg/week; 55.1 ± 9.8 infusions/year). HRQoL improved in both self-reports and parent reports. No severe adverse events occurred. CONCLUSION: Switching from SHL-FIX to EHL-FIX in children with haemophilia B is safe and may improve outcomes by reducing bleeding rates, infusion frequency, and factor consumption while enhancing joint health and HRQoL.