A Longitudinal, Observational Study of Previously Treated Hemophilia Patients Switching Factor Replacement Products
This is a longitudinal, observational study of patients with Hemophilia A or B who are planning to switch to a newly approved coagulation factor replacement product, or who have recently switched factor products. The study will follow each patient for up to 1 year. Patients will be recruited at Hemophilia Treatment Centers (HTC) which are ATHN-affiliates. The primary outcome being studied is the development of inhibitor (i.e., antibodies to factor) at 1 year or 50 exposure days, whichever comes first. The study will be conducted at approximately 30 HTCs, with a planned enrollment of 600 patients.The entire study duration is projected to be approximately 6 years. In addition, optional substudies will be included for some products, as Product-Specific Modules. These will be questionnaires to collect data for subjects receiving selected Factor products. For example, subjects receiving Kovaltry will be approached to participate in the 'Kovaltry Product-Specific Module'; subjects receiving Adynovate will be approached to participate in the 'Adynovate Product-Specific Module'. Questions will be related to product use, perceptions of product use, and other post-marketing consumer data.
• Moderate or Severe Congenital Hemophilia A or B (FVIII or FIX clotting activity less than or equal to 5% of normal).
• Able to give informed consent (by patient or parent/authorized guardian).
• Previously treated with plasma-derived or recombinant clotting factor replacement products with at least 50 exposure days (as assessed either from direct clinical records in children under age 5, or by clinical history of dosing in older patients). For Arm B being enrolled retrospectively, this previous treatment must be prior to product switch under study.
• Planning to switch, or recently switched within the previous 50 weeks, to a new brand or type of replacement factor VIII or IX, FDA approved after January 1, 2013.
• Arm B only: Negative inhibitor screen within the last 6 months prior to switching.
⁃ Note: History of prior transient inhibitor or inhibitor eradicated by immune tolerance induction (ITI) are eligible.