Real-World Effectiveness Data on Mild and Moderate Hemophilia a Patients Using Bay 81-8973 in the Athndataset
Authors: Chandler Martin , Charlet Jessica , Chrisentery-Singleton Tammuella 
Published: December 2024

Real-world data on recombinant factor VIII (rFVIII) product effectiveness are sparse for Hemophilia A patients with mild or moderate disease. The ATHNdataset, sponsored by the American Thrombosis and Hemostasis Network, includes 15,304 people with hemophilia A as of 30/11/23, a potential source of data to evaluate therapeutic effectiveness.
The aim of this retrospective analysis was to evaluate treatment effectiveness, regimens and characteristics of mild and moderate hemophilia A patients that are being treated with BAY 81-8973 (Kovaltry®) in a real-world setting.
The ATHNdataset was queried for hemophilia A patients with a baseline FVIII severity classified as mild or moderate using BAY 81-8973. Data included demographics, disease and treatment history, bleed rates, treatment regimens, inhibitor and target joint status. Query dates were between January 1, 2010 and November 30, 2023.
Out of 746 patients using BAY 81-8973 in the ATHN dataset, a total of 291 (39%) moderate and mild hemophilia A patients were using BAY 81-8973 either on demand (n=218, 75%) or prophylactically (n=73, 25%), which included intermittent prophylaxis, at data cut-off.
Of the 132 (45%) patients with moderate disease, 92 (68%) were treating on demand and 40 (32%) prophylactically (32 continuously and 8 intermittently); their mean age was 35.3 and 37.3 years, respectively. Two patients were female and treated on demand with Bay 81-8973. In both treatment modalities, most patients were white (&gt;70%) and not Hispanic (&gt;80%). In regard to infections, Hepatitis C was the most common one patients ever had, compared to Hepatitis B and HIV. The prevalence of ever having had FVIII inhibitors was at 8% for on demand and prophylactically treating moderate patients, while 3% in either treatment modality had recorded target joints at some point in time.
Moderate patients treating on demand, were using BAY 81-8973 in average for 2.0 years, while those on prophylaxis, used BAY 81-8973 for an average of 3.2 years with mean doses of 37 and 40 International Units (IU)/kg, respectively. Of the 40 patients treating prophylactically, 22% used BAY 81-8973 at a 2x/week regimen and 48% ≥3x/week; the rest were unknown.
The total annualized bleed rates (ABRs) were 0.32 for on demand treating patients and 0.70 for prophylactic users.
Of the 159 (55%) patients with mild disease, 126 (79%) were treating on demand and 33 (21%) prophylactically (15 continuously and 18 intermittently); their mean age was 38.4 and 37.0 years, respectively. Twenty-six patients were female, while 18 and 8 treated on demand and prophylactically with Bay 81-8973, respectively. In both treatment modalities, most patients were white (&gt;80%) and not Hispanic (&gt;70%). In regard to infections, Hepatitis C was the most common one patients ever had, compared to Hepatitis B and HIV. The prevalence of ever having had FVIII inhibitors was at 3% for on demand and prophylactically treating mild patients, while &lt;1% of patients in either treatment modality had recorded target joints at some point in time.
Mild patients treating on demand, were using BAY 81-8973 in average for 2.4 years, while those on prophylaxis, used BAY 81-8973 for an average of 3.1 years with mean doses of 35 and 33 IU/kg, respectively. Of the 33 patients treating prophylactically, 21% used BAY 81-8973 at a ≤2x/week regimen and 30% ≥3x/week; the rest were unknown.
The total ABRs were 0.15 for on demand treating patients and 0.17 for prophylactic users.
This observational, retrospective analysis provides descriptive data contributing to the understanding of mild and moderate hemophilia A patient care. 39% of all BAY 81-8973 users in the ATHN dataset were mild and moderate patients, with a slightly higher number of mild patients. Most patients, 79% and 68% were treating with an on-demand modality, respectively. The remaining patients treated prophylactically with BAY 81-8973, with 48% moderate vs 30% mild patients using a ≥3x/week regimen. ABRs were generally low for both on demand and prophylactically treating patients in both disease severities, supporting the benefit of using standard of care prophylaxis treatment in all hemophilia A patients. Without clinical evidence, the numerically slightly higher ABR in the prophylaxis vs on-demand groups, might be explained by a potentially more severe bleeding phenotype, requiring prophylaxis treatment in mild and moderate hemophilia A patients.