Bleeding risk in hemophilia A and B carriers: comparison of factor levels determined using chronometric and chromogenic assays

Delphine Chiffré-Rakotoarivony; Isabelle Diaz-Cau; Alexandre Ranc; Marie-Agnès Champiat; Florence Rousseau; Corinne Gournay-Garcia; Alexandre Théron; Robert Navarro; Pierre Boulot; Patricia Aguilar-Martinez; Pauline Sauguet; Christine Biron-Andréani

doi:10.1097/MBC.0000000000001305

Bleeding risk in hemophilia A and B carriers: comparison of factor levels determined using chronometric and chromogenic assays

Blood Coagul Fibrinolysis. 2024 Apr 29. doi: 10.1097/MBC.0000000000001305. Online ahead of print.

Authors

Affiliations

¹ Hemophilia Treatment Centre, Department of Biological Hematology.
² Department of Biological Hematology, Hematology Laboratory.
³ Department of Obstetrics and Gynecology, University Hospital, Montpellier, France.

PMID: 38700721
DOI: 10.1097/MBC.0000000000001305

Abstract

Background: Predicting the bleeding risk in hemophilia A and B carriers (HAC, HBC) is challenging.

Objective: The objectives of this study were to describe the bleeding phenotype in HAC and HBC using the standardized Tosetto bleeding score (BS); to determine whether the BS correlates better with factor levels measured with a chromogenic assay than with factor levels measured with chronometric and thrombin generation assays; and to compare the results in HAC and HBC.

Methods: This ambispective, noninterventional study included obligate and sporadic HAC and HBC followed at a hemophilia treatment center between 1995 and 2019.

Results and conclusion: The median BS (3, range 0-21 vs. 3.5, range 0-15, P = ns, respectively) and the abnormal BS rate (35.6% vs. 38.2%, P = ns) were not significantly different in 104 HAC and 34 HBC (mean age: 38 years, 6-80 years). However, some differences were identified. The risk of factor deficiency was higher in HBC than HAC. Specifically, Factor VIII activity (FVIII):C/Factor IX activity (FIX):C level was low (<40 IU/dl) in 18.3% (chronometric assay) and 17.5% (chromogenic assay) of HAC and in 47% and 72.2% of HBC ( P < 0.001). Moreover, the FIX:C level thresholds of 39.5 IU/dl (chronometric assay) and of 33.5 IU/dl (chromogenic assay) were associated with very good sensitivity (92% and 100%, respectively) and specificity (80% for both) for bleeding risk prediction in HBC. Conversely, no FVIII:C level threshold could be identified for HAC, probably due to FVIII:C level variations throughout life.