International Society on Thrombosis and Hemostasis Bleeding Assessment Tool (ISTH-BAT) and Intrinsic Rotational Thromboelastometry (INTEM-ROTEM) in the Evaluation and Classification of von Willebrand Disease (VWD): An Egyptian Center Cross-Sectional Observational Study.

Background: VWD is the most common inherited bleeding disorder, characterized by quantitative or qualitative defects of VWF. Accurate assessment of bleeding severity and disease classification remains clinically challenging. The ISTH-BAT standardizes bleeding history, while viscoelastic assays such as ROTEM may provide additional global hemostatic information. Objective: To evaluate the diagnostic performance of ISTH-BAT in VWD screening and severity assessment, and to investigate the role of INTEM-ROTEM parameters in VWD identification and classification, with correlation to conventional laboratory markers. Methods: This cross-sectional observational study included 69 patients diagnosed with VWD and 68 age- and sex-matched healthy controls. All participants underwent ISTH-BAT evaluation and standard VWD laboratory workup, including VWF antigen (VWF:Ag), VWF activity (VWF:GPIbM), and factor VIII (FVIII). INTEM-ROTEM analysis was performed in 44 patients. Correlation, regression, and receiver operating characteristic (ROC) curve analyses were conducted. Results: Total ISTH-BAT scores differed significantly across VWD types (p=0.047). Clotting time (CT) was the only INTEM-ROTEM parameter showing significant differences between VWD types (p=0.001) and subtypes (p=0.022). CT correlated negatively with VWF:Ag (r=-0.561, p<0.001) and FVIII (r=-0.664, p<0.001), and positively with aPTT (r=0.693, p<0.001). Regression analysis demonstrated that each 1-second increase in CT was associated with a 0.31% decrease in VWF:Ag (p=0.002) and a 0.48% decrease in FVIII (p<0.001). For VWF:Ag <10%, a CT >193 seconds predicted VWD with an AUC of 0.809. Conclusion: ISTH-BAT is a highly sensitive screening tool for VWD and correlates with disease severity. Among INTEM-ROTEM parameters, clotting time shows potential adjunctive value in distinguishing VWD severity, types and subtypes, and correlates significantly with conventional laboratory markers. INTEM-ROTEM CT may provide supportive diagnostic information in clinical settings requiring rapid hemostatic assessment.