Medication adherence after transition to emicizumab in patients with severe hemophilia A: Results from the ADHEMI study

<h2>Abstract</h2><h3>Background</h3> Hemophilia A (HA) is a rare X-linked congenital bleeding disorder characterized by a deficiency in coagulation factor VIII (FVIII). Standard treatment includes regular intravenous (IV) injections of clotting factor concentrates, known as prophylaxis. Recent advances, such as subcutaneous nonfactor replacement therapy like emicizumab, have had an impact on management strategies for patients with HA, notably by reducing the burden of IV injections. <h3>Objectives</h3> This study aimed to assess the change in medication adherence after the HA treatment modality switch from FVIII or bypassing agents (BPAs) in the case of inhibitors to subcutaneous emicizumab for patients with severe HA. <h3>Methods</h3> A multicenter retrospective study was conducted across 11 French reference centers for hemophilia. The study included 187 patients with severe HA treated with emicizumab for at least 12 months after a minimum of 12 months with FVIII or BPA prophylaxis. Medication adherence was measured using the medication possession ratio (MPR), calculated for both periods, accounting or not for the inclusion of emergency doses (EDs). These doses were prescribed in addition to the prophylactic regimen in the case of hemorrhage. <h3>Results</h3> Medication adherence statistically significant increased after switching to emicizumab (mean ± SD) (MPR 0.99 ± 0.07) compared with the previous period with FVIII or BPAs (MPR 0.85 ± 0.23 without EDs, 0.91 ± 0.24 with EDs, <i>P</i> < 0.001). The proportion of adherent patients (MPR ≥ 90%) rose from 44.4% (without EDs) and 54.5% (with EDs) to 92.0% after the switch (<i>P</i> < 0.001). <h3>Conclusions</h3> Switching to emicizumab improves medication adherence in patients with hemophilia A.