Designing ATHN 7: Safety, effectiveness and practice of treatment of people with haemophilia in the United States through a natural history cohort study

Abstract Background Haemophilia A and B are X-linked inherited bleeding disorders, resulting in the deficiency of clotting factor VIII and IX, respectively. Since the introduction of recombinant clotting factor concentrates in the early 1990s, the major safety concern for haemophilia therapy has been the development of inhibitory antibodies, or inhibitors. Over the recent past, new therapies for the treatment and prevention of bleeding have received regulatory approval or are under study. Objective ‘ATHN 7: A Natural History Cohort Study of the Safety, Effectiveess, and Practice of Treatment for People with Hemophilia is designed to determine the safety of current haemophilia therapies when used for participants with haemophilia with or without inhibitors. Secondarily, ATHN 7 will describe the real-world effectiveness of current therapies by assessing bleeding rate and location, therapy utilisation, adherence, and patient-reported outcomes. Methods This longitudinal, observational cohort study by the American Thrombosis and Hemostasis Network (ATHN) will follow participants with haemophilia with or without inhibitors for four years from the time of enrolment. Each participant is assessed every three months. All data are collected into ATHN Systems. The primary outcome measure is the incidence of safety events as defined by the European Haemophilia Safety Surveillance (EUHASS) programme. Effectiveness will be described based on annualised bleeding rate, therapy utilisation, adherence, and patient-reported outcomes. Conclusion As the first product-agnostic, real-world study of haemophilia therapy in the United States, ATHN 7 collects data to determine current intervention safety and effectiveness. Based on this success, ATHN will continue to collect these data longitudinally through the ATHN Transcends study.