Patients with moderate hemophilia A and B with a severe bleeding phenotype have an increased burden of disease

Background Patients with moderate hemophilia express varying bleeding phenotypes. Objectives To assess the burden of disease in patients with moderate hemophilia and a mild or severe phenotype incorporating the thrombin generation profile. Methods This sub-study of the 6th Hemophilia in the Netherlands study, analyzed data of adults with moderate hemophilia A or B. Patient characteristics and information on bleeding tendency, joint status, and quality of life were obtained from electronic patient files and self-reported questionnaires. A severe bleeding phenotype was defined as an annual bleeding rate ≥5, an annual joint bleeding rate ≥3, and/or the use of secondary/tertiary prophylaxis, and a mild phenotype vice versa. TG was measured with the Nijmegen Hemostasis Assay. Results This study included 116 patients: 21% had a severe phenotype of whom 46% used prophylaxis. Patients with a severe phenotype treated on demand reported a higher median annual bleeding rate (7), annual joint bleeding rate (3), and more frequently an impaired joint (77%) than patients with a severe phenotype on prophylaxis (2; 0; 70%) or patients with a mild phenotype (0; 0; 47%). Furthermore, patients with a severe phenotype treated on demand experienced a more decreased quality of life. Despite similar factor activity levels, patients with a severe phenotype had a lower thrombin peak height and thrombin potential (0.7%; 0.06%) than patients with a mild phenotype (21.3%; 46.8%). Conclusion Patients with moderate hemophilia and a severe phenotype treated on demand displayed a high burden of disease as well as a low thrombin generation profile advocating them toward more intensive prophylactic treatment.