Abstract Number: PB0878
Meeting: ISTH 2020 Congress
Theme: Hemophilia and Rare Bleeding Disorders » Hemophilia - Clinical
Background: Prophylaxis with rFVIIIFc in severe haemophilia A (HA) may reduce infusion frequency (IF) and clotting factor consumption (CFC) with improved bleeding outcomes in comparison with standard rFVIII. It is unclear if there is a cumulative effect on bleeding outcomes with time.
Aims: To describe bleeding outcomes associated with switching from standard rFVIII to rFVIIIFc prophylaxis over a three-year follow-up period in the UK.
Methods: All patients with ≥ 6 months rFVIIIFc follow-up in the UK were identified. Trial patients and patients with an inhibitor history or < 6 months Haemtrack (HT)-compliant data were excluded. Age, IF, CFC, ABR and AJBR were calculated and a subgroup analysis of those with 3 years follow-up was performed. Within-patient change in ABR over time and pre and post-switch comparisons were analysed using Wilcoxon signed rank testing, bleed-free proportion was analysed using the Χ2 McNemar test.
Results: The criteria were met by 198 patients; 183 with 2 years and 70 with 3 years follow-up. Within-patient analysis of 158 with ≥ 6 months pre- and post-switch HT data demonstrated significant reductions in IF and CFC and ABR and AJBR following switching (table 1). This was most marked in patients with a pre-switch ABR> 5. rFVIIIFc utilisation was stable over three-years follow-up. The proportion of bleed-free patients increased significantly from 36% to 53% over three years follow-up (Χ2=6.1 p< 0.01) (table 2). ABR reduced non-significantly over time. The results of the subset with three years follow-up were representative of the whole group.
Conclusions: The data suggest that rFVIIIFc may allow a reduction in infusion frequency and improved bleeding outcomes in comparison to rFVIII. There was a progressive increase in the proportion of bleed-free patients over time.
Pre-switch (n=158) | Post-switch (n=158) | Within-patient change | |
Age* med. (IQR) | 24 (11;43) | – | – |
Infusion frequency (week) med. (IQR) | 3.2 (2.6;3.6) | 2.3 (2.1;2.7) | -26% (-34;-5%) p<0.001 |
Clotting factor consumption (IU/kg/week) med. (IQR) n=152** | 81 (55;100) | 68 (52;89) | -12% (-30;5%) p<0.001 |
ABR med. (IQR) | 2.6 (0;7.2) | 2 (0;4) | -1 (-3.2;0.4) p<0.001 |
AJBR med. (IQR) | 1 (0;5) | 1 (0;3) | 0 (-1.9;0) p<0.001 |
Bleed-free rate | 28% | 32% | (Χ 2= 1.4; p=0.23) |
* as of the first treatment with rFVIIIFc **patients without weights were excluded |
[Table 1: Within-patient analysis before and after switching to rFVIIIFc]
n= 54 with ≥6 months pre-switch HT data | Year 1 n=70 | Year 2 n=70 | Year 3 n=70 | |
Infusion frequency (week) med. (IQR) | 3.4 (2.6; 3.7) | 2.2 (2.0; 2.7) | 2.2 (1.9, 2.6) | 2.3 (2.0, 2.7) |
Clotting factor consumption (IU/kg/week) | 81 (55;105) | 75 (60, 95) | 75 (57, 96) | 81 (62, 101) |
ABR med. (IQR) | 1.1 (0; 6) | 1 (0, 3.8) | 1 (0, 3) | 0 (0, 2.9) |
Bleed-free rate | 29% | 36% | 41% | 53% |
AJBR med. (IQR) | 1 (0; 3.8) | 1 (0, 2.8) | 0 (0, 2) | 0 (0, 1.5) |
Within-patient change in ABR (Y3 vs Y1) | – | 0 (-1,1), p=0.37 | ||
Within-patient change in ABR (Y3 vs Y2) | – | 0 (-1, 0.5), p=0.78 | ||
Within-patient change in ABR (Y2 vs Y1) | – | 0 (-1, 0), p=0.94 | ||
Within-patient change in ABR (Y3 vs rFVIII pre-switch) | -1 (-2.5, 0), p<0.01 |
[Table 2: Subgroup analysis of patients with 3 years follow-up data and within-patient analysis of change in ABR over time (lower table)]
To cite this abstract in AMA style:
Wall C, Scott M, Xiang H, Palmer B, Collins P, Chowdary P, Dolan G, Curry N, Allsup D, Hay C, Hart D, UK National Haemophilia Database . Longitudinal Analysis of rFVIIIFc Use and Efficacy in the UK: A Report from the National Haemophilia Database [abstract]. Res Pract Thromb Haemost. 2020; 4 (Suppl 1). https://abstracts.isth.org/abstract/longitudinal-analysis-of-rfviiifc-use-and-efficacy-in-the-uk-a-report-from-the-national-haemophilia-database/. Accessed March 21, 2024.« Back to ISTH 2020 Congress
ISTH Congress Abstracts - https://abstracts.isth.org/abstract/longitudinal-analysis-of-rfviiifc-use-and-efficacy-in-the-uk-a-report-from-the-national-haemophilia-database/