Navigating Hemophilia B
Joints (most commonly the elbow, knee, and ankle) are the site of approximately 92% of bleeds in severe hemophilia.1,7 Other common sites of bleeding are the muscles, the brain, and mucosal tissues (mouth, epistaxis, gastrointestinal, and genitourinary tract).1 Recurrent bleeding into the same joint may eventually cause hypertrophic synovitis, progressive cartilage degradation, hemophilic arthropathy, and significant impairment of joint function.7,8
Treatment of Hemophilia B involves replacement therapy in which the deficient endogenous FIX is replaced via intravenous infusion.9,10 The standard of care in Hemophilia B has shifted towards prophylactic treatment, with the goal of preventing all bleeds, rather than on-demand or episodic treatment in response to a bleeding episode. World Federation of Hemophilia (WFH) guidelines recommend individualized prophylaxis based on bleeding phenotype, joint status, individual pharmacokinetics, and patient self-assessment and preference.1
The most severe treatment-related complication in hemophilia is the development of inhibitors, which are alloantibodies to administered factor replacement therapy.11 The lifetime incidence of inhibitors is lower in Hemophilia B than in Hemophilia A (3-5% of severe Hemophilia B patients vs 25-30% of severe Hemophilia A patients). In contrast with FVIII inhibitors, FIX inhibitors are associated with severe anaphylactic reactions to the infusion of FIX-containing products in about half of patients with inhibitors.