Health Equity Impacts of Funding Emicizumab in People with Severe Hemophilia a in the US: An Aggregate Distributional Cost-Effectiveness Analysis
Authors: Majda Thomas , Lee Janet S , Curtis Randall , Kowal Stacey L 
Published: December 2024

Introduction: Racial and ethnic differences in disease risk, outcomes and treatment are documented among people with hemophilia A (PwHA) in the US. For example, Black individuals with severe HA are approximately 1.5 times more likely to have inhibitors to factor VIII (FVIII) relative to their White counterparts. Emicizumab is the first bispecific antibody approved for prophylaxis in adult and pediatric PwHA with or without FVIII inhibitors. Aggregate distributional cost-effectiveness analysis (A-DCEA) is an extension of cost-effectiveness analysis that incorporates the health equity impact of funding an intervention and can be used in decision-making. An A-DCEA evaluates how health effects and costs are distributed among population subgroups of interest, while considering trade-offs between improving health at the population level vs reducing health inequality. The objective was to evaluate how emicizumab impacts overall health and health disparities in people with severe HA in the US.

Methods: Using previously established methods for A-DCEA, the net health benefits of emicizumab were estimated based on prior cost-effectiveness analyses from the Institute for Clinical and Economic Review (ICER) and added to the baseline distribution of population health. This analysis considered equity impacts on people with severe HA treated with emicizumab and the potential consequences or opportunity costs of funding emicizumab over other interventions on the full US population. The US population was divided into 25 subgroups of interest based on race and ethnicity and county-level social vulnerability index. A targeted literature review was conducted to extract model inputs related to disparities among people with severe HA and the proportion with FVIII inhibitors by race and ethnicity. Cost-effectiveness model results from 3 previous ICER reviews of emicizumab (2018, 2020, 2022) were inflated to 2024 USD and weighted according to inhibitor status and internal projected 2024 prophylaxis market shares. Using a threshold of $150,000 per quality-adjusted life-year (QALY), opportunity costs were calculated by converting the cost of funding emicizumab treatments into QALYs. Various scenarios were explored to assess the equity impacts on improved access to emicizumab.

Results: Funding emicizumab is projected to improve health (ie, QALYs) in all subgroups of interest and reduce population inequalities given larger relative health gains in populations with the largest existing disparities (ie, the Black subpopulation) and the benefits gained from health system savings from treatment. Larger relative health gains in Black subgroups are driven by lower baseline health and increased QALY gains from the higher prevalence of inhibitors in Black individuals with severe HA, where use of emicizumab leads to larger QALY gains relative to bypassing agents. When severe PwHA are treated with emicizumab over their lifetime, the healthcare system is projected to save $25 million on average per patient vs all weighted comparators, driven primarily by emicizumab's total cost-of-care savings vs bypassing agents and factor products. When an estimated 6512 severe PwHA in the US are treated with emicizumab, the US health system saves between $160 and $172 billion over those individuals' lifetimes. When these cost savings are applied to support additional healthcare interventions in the overall population, funding emicizumab increases social welfare by improving overall US population health (up to 1.1 million QALYs gained) and reduces existing overall US inequities. All scenarios examining a larger amount of people with severe HA treated with emicizumab lead to further reductions in US health disparities and greater increases to overall US population health.

Conclusions: In this first A-DCEA conducted for emicizumab in people with severe HA, funding emicizumab provided the greatest health benefit among Black PwHA, mostly due to its cost-effectiveness in the population with FVIII inhibitors and the higher prevalence of inhibitors in the Black population. Thus, funding emicizumab for treatment of severe HA may improve overall population health and reduce overall health inequities in the US. Further, the cost savings from emicizumab may free up significant resources that can be leveraged to support other healthcare interventions across the US population.