Real World Use of Extended Half-Life Products and the Impact on Bleeding Events and Joint Health in the United States

Background: The hemophilia treatment landscape has evolved substantially in the last several years with the approval of extended half-life (EHL) products which reduce the burden of prophylaxis. Data reported from the American Thrombosis and Hemostasis Network (ATHN) as of June 2017 indicate that 21% of patients with moderate or severe hemophilia A, and 42% of patients with moderate or severe hemophilia B, receive prophylaxis utilizing an EHL. As new treatments become available and are adopted into practice, it is important to recognize the need for evaluation of efficacy, safety, and economic impact of their use outside of the clinical trial setting. We aimed to characterize the real world impact of EHL products by collecting detailed information on bleeding rates, joint health and quality of life amongst patients cared for at ATHN-affiliated Hemophilia Treatment Centers. We hypothesized that use of EHL products were utilized in at least 30% of patients and would lead to decreased ABRs and improved joint health. To date 67 of a planned 135 subjects have been enrolled, constituting this interim analysis. Methods:Subjects were recruited from seven U.S. Hemophilia Treatment Centers. Subjects with severe hemophilia A or B ≤ 30 years of age on prophylaxis or demand therapy were eligible for enrollment. Subjects excluded from study were those with a recent joint bleed (within the last 2 weeks) or those unwilling to complete all elements of the study. Data were collected during a one-time encounter concurrent with an appointment for clinical evaluation, including demographic information, treatment regimen, product type, frequency, location and severity of all bleeds, Hemophilia Joint Health Scores (HJHS), and Quality of life (QoL). Bleeding rates in subjects receiving prophylaxis were compared with those receiving on demand therapy by type treatment, EHL vs standard half-life (SHL), and by hemophilia type. Severity of bleeding events (mild, moderate, or severe) and HJHS were compared by prophylaxis groups. Results: A total of 67 patients were enrolled and eligible for analysis. This included 58 subjects with severe hemophilia A, and 9 subjects with severe hemophilia B. The mean age of the cohort was 15 years (median 12 years, IQR 8 - 21 years). For these patients whose race information was known, 89.1% were Caucasian, 3.3% African-American, 3.3% Asian, and 4.7% were of mixed or ‘other’ race. Eleven out of 61 (18.0%) subjects with known ethnicity were Hispanic. Am