Bleeding severity in patients with rare bleeding disorders: real-life data from the RBiN study

Area of Science:

• Hematology
• Rare Diseases
• Clinical Genetics

Background:

• Hereditary rare bleeding disorders (RBDs) cause varied hemorrhagic symptoms.
• The link between factor activity levels and bleeding severity in RBDs is often poor.
• Previous threshold factor activity levels for predicting bleeding require validation.

Purpose of the Study:

• To investigate the correlation between factor activity levels and bleeding severity in patients with RBDs.
• To evaluate the accuracy of previously established threshold factor activity levels.
• To compare the efficacy of the ISTH Bleeding Assessment Tool (BAT) and an RBD-specific BAT.

Main Methods:

• A nationwide cross-sectional study (Rare Bleeding Disorders in the Netherlands - RBiN) included 263 patients (age 1-99) with known RBDs.
• Bleeding scores were assessed using the ISTH BAT and an RBD-specific BAT.
• Laboratory and clinical data, including baseline factor activity levels, were extracted from patient files.

Main Results:

• Strong correlations between factor activity and bleeding severity were found for FII and FX deficiencies.
• Moderate correlations were observed for fibrinogen, FV, FVII, FXIII, and α2-antiplasmin deficiencies; no correlation for FXI.
• 48% of patients had more severe bleeding than predicted, and 34% predicted as asymptomatic experienced significant bleeding.

Conclusions:

• Bleeding severity in RBDs is frequently more pronounced than previously anticipated.
• Established threshold factor activity levels for predicting bleeding in RBDs are inaccurate.
• The RBD BAT identified more women and children with RBDs compared to the ISTH BAT.