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

## TL;DR

Switching from standard to extended half-life FIX in children with haemophilia B reduces bleeding and improves quality of life.

## Contribution

Demonstrates the safety and benefits of switching to EHL-FIX in pediatric haemophilia B patients.

## Key findings

- Annual bleeding rates decreased from 6.01 to 2.85 after switching to EHL-FIX.
- Factor consumption and infusion frequency were significantly reduced with EHL-FIX.
- Health-related quality of life improved with no severe adverse events observed.

## Abstract

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.

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.

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.

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.

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.