Discrepancy between one-stage clotting and chromogenic factor VIII activity in women with hemophilia A and hemophilia A carriers: a retrospective clinical study.

Background: For every man diagnosed with hemophilia, approximately 1.6 women are expected to be carriers. Carriers are classified based on their factor (F) VIII levels and symptoms, ranging from asymptomatic to mild, either moderate or severe symptoms. Close monitoring is critical for carriers with low FVIII levels or bleeding symptoms, as the bleeding risk is difficult to assess due to inconsistent correlations with routine one-step assay (OSA) measurements.

Objectives: This study hypothesized that the chromogenic FVIII assay (CSA) may provide valuable information for estimating the bleeding risk in some hemophilia carriers.

Methods: This retrospective study included 109 hemophilia A carriers from 2 centers.

Results: Among them, 23% had FVIII levels <40 IU/dL when assessed using OSA, while 41% showed discrepancies when assessed using CSA. von Willebrand factor activity and antigen levels were normal, with mean values of 84 IU/dL and 107, respectively. There was a significant correlation between OSA and CSA FVIII results, although 20 women had discordant results between the 2 methods. Bleeding events were reported in 49 women, including 18 surgical complications, 1 joint bleeding episode, and 30 cases of heavy menstrual bleeding, all occurring with normal von Willebrand factor levels. There were 157 pregnancies in which 14 cases of postpartum hemorrhage were observed, 3 of which required transfusion or surgery.

Conclusion: This study highlights the significant discrepancies between OSA and CSA in FVIII results, with implications for diagnosis and bleeding risk assessment. It emphasizes the need to use both methods to identify women at a higher risk of bleeding, especially before surgery.