Real-World Persistence with and Adherence to Emicizumab Prophylaxis in Persons with Hemophilia a: A Secondary Claims Database Analysis

Introduction: Emicizumab is a subcutaneously administered, humanized bispecific monoclonal antibody, approved for routine prophylaxis in persons with hemophilia A (PwHA) with or without factor VIII inhibitors. Little is known about patterns of emicizumab use in clinical practice. We aimed to evaluate real-world persistence with and adherence to emicizumab treatment for PwHA on prophylaxis.

Methods: This retrospective study used de-duplicated commercial insurance claims data from IBM^® MarketScan^® Commercial Research and IQVIA PharMetrics^® Plus databases from 16 November 2017 to 31 December 2019. Individuals included met the following criteria: 1) evidence of emicizumab use (at least two prescription fills) and 2) continuous enrollment for at least three months pre-emicizumab initiation. Individuals were followed until the end of study period or continuous enrollment. Persistence was defined as the proportion of individuals continuing treatment with emicizumab during the study period. Time to discontinuation and proportion of individuals who restarted emicizumab prophylaxis were reported for patients who discontinued emicizumab. Discontinuation was defined as 60 days without a prescription fill. Adherence was measured over the post-index persistence period using the proportion of days covered (PDC), and the proportion of individuals adherent at ≥80% PDC threshold was reported.

Results: We identified 328 unique individuals who met the inclusion criteria. All patients were male (100%); the average age was 23 years (standard deviation [SD] ±16; range=1-64); and the average follow-up post-index was eight months (245±147 days). The vast majority of individuals (92%) were persistent with emicizumab prophylaxis during the study period. Among those who discontinued emicizumab (n=25), the average time to discontinuation was approximately three months (84±124 days); 40% restarted emicizumab prophylaxis after discontinuation, with an average time to restart of approximately four months (126±56 days). During the period for which individuals were persistent to treatment, adherence to emicizumab was high (81%); with 70% individuals meeting the ≥80% PDC threshold. Among those with at least one-year post-index enrollment (n=48), adherence during the first year was also high (85%), with 77% individuals adherent at the ≥80% PDC threshold.

Conclusions: In this study, the vast majority of individuals treated with emicizumab had high rates of adherence and persistence to treatment. This is one of the first studies to report real-world persistence with and adherence to emicizumab prophylaxis in PwHA. Future evaluations should examine the association of persistence and adherence with health outcomes in this population.