No Peak of New-onset Inhibitors in the Aging Hemophilia Population: An International, Retrospective, Observational, Cohort Study of New Inhibitors in People with Hemophilia Aged 40 Years and Older (the NIAP Study)

J. Astermark¹, M. Carvalho², P. De Moerloose³, R. D'Oiron⁴, G. Dolan⁵, P. Fontana³, C. Hermans⁶, P.A. Holme⁷, O. Katsarou⁸, G. Kenet⁹, R. Klamroth¹⁰, A. Lubetsky⁹, M.E. Mancuso¹¹, N. Marquardt¹², R. Núñez¹³, I. Pabinger-Fasching¹⁴, R. Schutgens¹⁵, C. Tait¹⁶, ADVANCE Working Group

¹Department of Hematology, Oncology and Radiation Physics, Center for Thrombosis and Hemostasis, Skåne University Hospital Malmö, Malmö, Sweden, ²Congenital Coagulopathies Reference Centre, Centro Hospitalar Universitário São João, Porto, Portugal, ³University Hospitals of Geneva, Geneva, Switzerland, ⁴APHP, Université Paris Saclay, Hôpital Bicêtre, Le Kremlin-Bicêtre, Paris, France, ⁵Guy's and St Thomas' Hospital, London, United Kingdom, ⁶Cliniques universitaires Saint-Luc, Université catholique de Louvain, Brussels, Belgium, ⁷Dept of Haematology, Oslo University Hospital and Institute of Clinical Medicine, University of Oslo, Oslo, Norway, ⁸Laiko General Hospital of Athens, Athens, Greece, ⁹Sheba Medical Center, Tel Hashomer, Ramat Gan, Israel, ¹⁰Vivantes Hospital, Berlin, Germany, ¹¹Angelo Bianchi Bonomi Haemophilia and Thrombosis Centre, Milan, Italy, ¹²University Hospital Bonn, Bonn, Germany, ¹³Virgen del Rocío University Hospital, Seville, Spain, ¹⁴Medical University of Vienna, Vienna, Austria, ¹⁵University Medical Centre Utrecht, Utrecht, the Netherlands, ¹⁶Glasgow Royal Infirmary, Glasgow, United Kingdom

Abstract Number: PB1071

Meeting: ISTH 2020 Congress

Theme: Hemophilia and Rare Bleeding Disorders » Hemophilia - Clinical

Background: A second peak of inhibitor development above age 60 in patients with severe hemophilia A has been suggested (Hay et al, Blood 2011), but not confirmed in other cohorts.

Aims: To further investigate, we identified and characterized patients with inhibitors diagnosed and treated within the frame of the ADVANCE Working Group, a European collaboration of hemophilia centers focused on the management of hemophilia at older ages.

Methods: Data were collected for 2,562 patients with hemophilia A aged ≥40 years from 16 centers over a retrospective period of 10 years.

Results: Fifty-eight patients were identified as having developed an inhibitor of any kind at age 40 and above; 19/1,222 (1.5%) severe of whom 5/276 (1.8%) were ≥60 years, 12/323 (3.7%) moderate, 25/1,017 (2.5%) mild and 2 not characterized. FVIII prophylaxis was in use at the time of inhibitor diagnosis/relapse in 74% of all severe HA patients, 33% moderate and 8% mild. Further data were collected on 43 patients via questionnaire on treatment, previous surgery and mutation. Overall, the use of prophylaxis was reported in 7/15 severe patients, 3/10 moderate and 1/18 mild patients. Among the 43 inhibitor patients, 32 were treated on-demand, of which the majority received rFVIII. All type of FVIII mutations were identified. The inhibitor was identified as a relapse of a previous inhibitor in 6 patients (3 severe). Most patients (26/43) had a history of surgery, trauma and/or serious infection in the 3 months preceding inhibitor identification; 23 of whom had a prior surgery (5/15 severe and 18/28 non-severe).

Conclusions: Although retrospectively collected, the evaluation of our relatively large cohort of closely monitored patients does not indicate a significantly higher incidence of new inhibitors than expected, and mainly associated with immune challenges. Most patients aged ≥40 years received FVIII prophylaxis, suggesting a potential value in regular exposure to maintain a tolerant state.

To cite this abstract in AMA style:

Astermark J, Carvalho M, De Moerloose P, D'Oiron R, Dolan G, Fontana P, Hermans C, Holme PA, Katsarou O, Kenet G, Klamroth R, Lubetsky A, Mancuso ME, Marquardt N, Núñez R, Pabinger-Fasching I, Schutgens R, Tait C, ADVANCE Working Group . No Peak of New-onset Inhibitors in the Aging Hemophilia Population: An International, Retrospective, Observational, Cohort Study of New Inhibitors in People with Hemophilia Aged 40 Years and Older (the NIAP Study) [abstract]. Res Pract Thromb Haemost. 2020; 4 (Suppl 1). https://abstracts.isth.org/abstract/no-peak-of-new-onset-inhibitors-in-the-aging-hemophilia-population-an-international-retrospective-observational-cohort-study-of-new-inhibitors-in-people-with-hemophilia-aged-40-years-and-older-th/. Accessed October 1, 2023.

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