Clinical application of extended half-life factor VIII in children with severe haemophilia A.

Introduction: Only few studies have presented results from real-world clinical use of Extended Half-Life (EHL) products in children with haemophilia (CWH).

Aim: To retrospectively examine real-life experience with EHL factor VIII products use in CWH A, comparing with clinical experience from standard half-life products (SHL).

Methods: A retrospective review of medical records of CWH A who have been prescribed EHL factor concentrates was conducted. All before/after comparisons were performed with the Wilcoxon matched-pairs signed-ranks test.

Results: Twenty-three children with severe haemophilia A were enrolled in the study (3-6 years old: n = 4, 7-12 years old: n = 7 and 13-18 years old: n = 12). Median length of time that patients were treated with EHL products was 78 weeks. Median dosing interval was significantly lengthened from 2.3 to 3.5 days after switching from SHL to EHL concentrates. Mean trough FVIII levels were significantly increased from 2.3% to 4.1% after treatment with EHL products. Also, CWH A had a reduction of mean annual bleeding rate (ABR) and mean annual joint bleeding rate (AJBR) from 1 and .8 to .3 and .2, respectively, following treatment with EHL concentrates (ABR: p = .02, AJBR: p = .05). However, after switching to factor EHL, actual FVIII consumption, including bleeds, was significantly increased from 94 IU/kg/week to 118 IU/kg/week in CWH A. There was no inhibitor development.

Conclusion: This study demonstrates the successful transition of 23 CWH A from SHL to EHL factor concentrates.