PB1227 - Lupus anticoagulant in acquired hemophilia A subjects in Quebec: data from the Quebec Reference Center for Inhibitors

Tuesday, June 27, 2023

18:30 – 19:30 ET

Room: Exhibition

Presenting Author(s)

Clémence Merlen, PhD (she/her/hers)

Research Associate
Division of Hematology-Oncology, CHU Sainte-Justine, Université de Montréal
Montreal, Quebec, Canada

Co-Author(s)

RY

Ronald Yan

MD
Department of Hematology, Dalhousie University
Halifax, Nova Scotia, Canada
KR

Katherine Robinson

Director of Bleeding Disorder Clinic
Division of Hematology , Department of Medicine , Department of Pathology
Halifax, Nova Scotia, Canada
JS

Jean St-Louis

Pediatric Hematologist-Oncologist
Division of Hematology-Oncology, Department of Pediatrics, Université de Montréal, CHU Sainte-Justine, Montréal, Quebec, Canada.
Montreal, Quebec, Canada
GR

Georges-Etienne Rivard

Medical Director, Hemophilia Center, CHU Sainte-Justine
Division of Hematology-Oncology, Department of Pediatrics, Université de Montréal, CHU Sainte-Justine, Montréal, Quebec, Canada
Montreal, Quebec, Canada
AB

Arnaud Bonnefoy

Associate Professor
Division of Hematology-Oncology, CHU Sainte-Justine, Université de Montréal
Montreal, Quebec, Canada

Background: Acquired hemophilia A (AHA) is a rare bleeding disorder caused by autoantibodies to factor VIII (FVIII). Laboratory diagnosis of AHA initially involves a step to exclude the presence of lupus anticoagulant (LAC) which interferes with AHA testing. Rare cases of coexistence of anti-FVIII and anti-phospholipid antibodies (APA) are described in the literature, requiring patient management adapted to the risks of thrombosis inherent in LAC.

Aims: To determine the occurrence of APA in AHA patients and their relationship with underlying conditions and clinical outcomes.

Methods: Plasma samples of 115 AHA patients referred to the Quebec Reference Center for Inhibitors (QCRI) between 2000 and 2021 were tested for LAC with the diluted Russel Viper Venom Time assay (dRVVT). Positive results were confirmed with a second assay using an excess of phospholipids to neutralize remaining LAC. Detailed information regarding underlying clinical conditions and outcomes were available for 58/115 patients. The study was approved by the Research Ethics Committee of CHUSJ and was supported by the Canadian Hemophilia Society.

Results: Eighteen percent of AHA patients (21/115) were found positive for LAC after dRVVT confirmation. No association was found between a positive LAC result and underlying conditions or clinical outcomes (Table 1).

Conclusion(s): A significant proportion of AHA patients also have LAC as measured by a dRVVT assay. No clinical difference in death, remission, relapse, or complications related to AHA treatment was observed in dRVVT-negative compared to dRVVT-positive AHA patients. The main limitation of this study, which requires further investigation, is that a negative dRVVT result does not definitely exclude the presence of a LAC. We could not ascertain whether the management of AHA patients with LAC was different from other AHA patients, which may have influenced patients’ outcomes.