Bleeding Disorder of Unknown Cause In the Netherlands (BDUC-iN Study)
The purpose of the Bleeding Disorder of Unknown Cause in the Netherlands study (BDUC-iN) is to learn more about unexplained bleeding in individuals with a bleeding disorder of unknown cause (BDUC). The study aims to better understand why these individuals have increased bleeding and how it affects their health and daily life. The main questions of this study are: 1. What are the mechanisms underlying the bleeding tendency in BDUC? 2. How do bleeding symptoms affect patients' daily functioning and overall health-related quality of life? 3. How is care delivered to individuals with BDUC, and how can this be improved? Participants with increased bleeding tendency who remain undiagnosed after standard coagulation testing and are consequently classified as having BDUC will be enrolled across the Hemophilia treatment centers in the Netherlands. Participants will undergo blood sampling for advanced hemostasis testing and genetic analysis. In addition, participants will complete validated questionnaires to assess bleeding symptoms and health-related quality of life. Participants will be followed longitudinally to evaluate how bleeding symptoms affect daily activities, medical procedures, and overall health-related quality of life.
• Referred to a (pediatric) hemostasis specialist for evaluation of bleeding tendency.
• Increased bleeding tendency based on: Abnormal International Society on Thrombosis and Haemostasis Bleeding Assessment Tool (ISTH-BAT) score (≥ 5 in women age 18-30; ≥ 6 in women age 31-51, ≥ 7 in women age 52 or older; ≥4 in men and ≥ 3 in children) OR Clinical gestalt according to the investigating physician
• Absence of diagnostic test results for a bleeding disorder in standard laboratory hemostasis tests:
• Complete blood count: Hemoglobin \> 6.0 mmol/L; thrombocyte count \> 100 x10\^9/L
• Prothrombin (PT) and activated Partial Thromboplastin Time (aPTT): within local reference range, or prolonged without explanatory factor deficiency
• Fibrinogen activity, von Willebrand Factor (VWF) antigen \& activity, Factor VIII, IX, XI and XIII: within local reference range or abnormal but not explaining bleeding phenotype
• Light transmission aggregometry (LTA): Not diagnostic for a platelet function
• Kidney function: eGFR \> 45 ml/min
• Liver function: ALAT, bilirubin \< 3 x upper limit of normal