eprintid: 10204033
rev_number: 6
eprint_status: archive
userid: 699
dir: disk0/10/20/40/33
datestamp: 2025-01-28 11:28:58
lastmod: 2025-01-28 11:28:58
status_changed: 2025-01-28 11:28:58
type: article
metadata_visibility: show
sword_depositor: 699
creators_name: Kamel, Kirollos
creators_name: Sardo Infirri, Sofia
creators_name: Riddell, Anne
creators_name: Chowdary, Pratima
creators_name: Batty, Paul
title: Factor VIII Antibodies Demonstrate Type I or Type II Kinetics in Acquired Haemophilia A
ispublished: inpress
divisions: UCL
divisions: B02
divisions: C10
divisions: D19
divisions: G98
keywords: acquired haemophilia, factor VIII, inhibitor, kinetics
note: © The Author(s), 2025. This is an Open Access article distributed under the terms of the Creative Commons Attribution Licence (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. https://creativecommons.org/licenses/by/4.0/
abstract: Background:
Acquired haemophilia A (AHA) is an acquired bleeding disorder resulting from autoantibodies against Factor VIII (FVIII). Previous studies have reported differences in FVIII inhibitor kinetics (type I or type II) in AHA compared to severe haemophilia A.//

Aim:
To characterise inhibitor kinetics in AHA and evaluate the proportions displaying type I, II or indeterminate kinetics. //

Methods:
Single-centre retrospective study of inhibitor kinetics in adults with AHA. Type I kinetics were defined as linear FVIII inhibition with ≥ 97% FVIII inactivation. Type II kinetics were defined as non-linear kinetics and inability to completely neutralise FVIII. Inhibitor titres were calculated using two methods outlined by the International Council for Standardisation in Haematology.//

Results:
Baseline samples from 34 patients were included. Fifteen samples (44.1%) exhibited type I kinetics, 16 samples (47.1%) exhibited type II kinetics and 3 (8.8%) were indeterminate. Plateau mean residual FVIII:C was higher for inhibitors displaying type II compared to type I kinetics (18.6 vs. 2.9 IU/dL, p < 0.0001). Non-linear regression using a dose-response curve without categorisation for kinetics type yielded a poor fit (R2 = 38%), which improved with refitting using categories of type I or II kinetics that explained 87% and 85% of the variability. The median difference in inhibitor titre between the two reporting methods was 5% and 15% in the type I and II kinetics groups, respectively.//

Conclusion:
FVIII autoantibodies demonstrate either type I or type II kinetics. Greater discrepancy in reported inhibitor titres depending on the method used is seen for inhibitors with type II kinetics.
date: 2025-01-15
date_type: published
publisher: Wiley
official_url: https://doi.org/10.1111/hae.15144
oa_status: green
full_text_type: pub
language: eng
primo: open
primo_central: open_green
verified: verified_manual
elements_id: 2354319
doi: 10.1111/hae.15144
medium: Print-Electronic
lyricists_name: Batty, Paul
lyricists_name: Chowdary, Pratima
lyricists_id: PBATT89
lyricists_id: CHOWD41
actors_name: Batty, Paul
actors_id: PBATT89
actors_role: owner
full_text_status: public
publication: Haemophilia
event_location: England
issn: 1351-8216
citation:        Kamel, Kirollos;    Sardo Infirri, Sofia;    Riddell, Anne;    Chowdary, Pratima;    Batty, Paul;      (2025)    Factor VIII Antibodies Demonstrate Type I or Type II Kinetics in Acquired Haemophilia A.                   Haemophilia        10.1111/hae.15144 <https://doi.org/10.1111/hae.15144>.    (In press).    Green open access   
 
document_url: https://discovery.ucl.ac.uk/id/eprint/10204033/1/Haemophilia%20-%202025%20-%20Kamel%20-%20Factor%20VIII%20Antibodies%20Demonstrate%20Type%20I%20or%20Type%20II%20Kinetics%20in%20Acquired%20Haemophilia%20A.pdf