PB1069 - Utility of ISTH Bleeding Assessment Tool in identifying bleeders and predicting bleeding severity in inherited primary and secondary haemostasis defects

Background: The ISTH-Bleeding Assessment Tool(BAT) was devised to aid in identification of patients with bleeding diathesis by improving reproducibility of bleeding history. The utility of ISTH-BAT in assessing bleeding severity is still elusive.

Aims: To assess the utility of ISTH-BAT to identify probable bleeders with primary or secondary haemostasis defects and to differentiate between severe and non-severe bleeders.

Methods: Participants referred for bleeding workup were recruited and grouped into “bleeders” and “non-bleeders” based on established cut-offs for abnormal BAT Score (males:>3, females:>5, children:>2). Patients were also grouped according to clinical bleeding severity into “severe bleeders” and “non-severe bleeders”. Severe bleeders were defined as those with life-threatening hemorrhages, multiple muscle hematomas, umbilical cord, gastrointestinal, CNS bleeding, >2 joints involvement by hemathroses or factor concentrate/transfusion requirement >5 times/year. Non-severe bleeders were defined as those who bled only after trauma/surgery, bled less frequently, < 2 joints involvement, less transfusion requirement, only minor symptoms like mucocutaneous bleeds. Detailed coagulation workup was performed including one-stage clot-based factor assays, light transmission aggregometry, ristocetin-cofactor assay and von willebrand antigen. Participants with normal results were taken as controls.

Results: A total of 76 controls and 395 patients (primary haemostasis defects n=244, secondary haemostasis defects n=151) were recruited. Patients had ISTH-BAT score ranging from 0 to 28 (Median:7,IQR:5-11). Age of patients ranged from 6days to 69years (Median:11years). ISTH-BAT score had overall 98.21% sensitivity, 95% negative predictive value(NPV) to identify bleeders with primary haemostasis defects, and 93.3% sensitivity, 91.9% NPV to identify bleeders with secondary haemostasis defects. The sensitivity and NPV further increased to 100% for severe bleeders with Glanzmann Thrombasthenia, Bernard Soulier Syndrome, VWD and Severe Hemophilia A/B(Figure1). There was significant overlap up to a score of 15 between clinically severe and non-severe bleeders(Figure2).

Conclusion(s): ISTH-BAT is very useful screening tool to identify bleeders with primary/secondary haemostasis defects but may not predict bleeding severity.