# Association of Patient-Reported Outcomes with Hemophilia A Inhibitor Status and Treatment Product Type

## TL;DR

The study found that patients with hemophilia A who use emicizumab and those who have tolerized inhibitors report fewer joint bleeds and better quality of life.

## Contribution

This study is novel in comparing PROs among hemophilia A patients based on inhibitor status and treatment type, including the impact of emicizumab.

## Key findings

- Participants with tolerized inhibitors reported the fewest joint bleeds and highest quality-of-life scores.
- Emicizumab users had significantly fewer bleeds compared to those on standard or extended half-life factor VIII.
- Active inhibitor patients had joint bleeding rates similar to those without inhibitors, likely due to emicizumab use.

## Abstract

Objectives: We compared patient-reported outcomes (PROs) in persons with hemophilia A (PwHA) by inhibitor status and prescribed treatment products. Methods: Hematology Utilization Group VIII study enrolled PwHA aged ≥ 2 years to collect PRO data via surveys. A clinical chart review documented the hemophilic severity, inhibitor level and treatment regimen. PROs were compared across inhibitor status and prescribed treatment products. Results: Among 85 enrolled PwHA, 9 (10.6%) had active inhibitors, 22 (25.9%) had tolerized inhibitors, and 54 (63.5%) had no inhibitors. The no-inhibitor group was significantly older (mean: 29.3 ± 13.5 years) than the tolerized (16.3 ± 9.5 years) and active inhibitor (21.9 ± 19.1 years; p = 0.001) groups. A larger proportion of participants with active inhibitors (66.7%) and no inhibitors (53.7%) reported having bleeds in the previous month compared to those with tolerized inhibitors (22.7%, p = 0.02). After covariate adjustment for age and hemophilia severity, the tolerized inhibitor group showed the lowest estimated number of joint bleeds compared to those of the no inhibitor and active inhibitor groups (p = 0.08), and the highest EQ-5D index score (p = 0.09). Emicizumab users reported significantly fewer bleeds in the previous months than those who were prescribed standard or extended half-life factor VIII (33.3% vs. 58.6%, 64.3%, p = 0.04). Conclusions: Participants with active inhibitors experienced joint bleeding rates similar to those of participants without inhibitors, likely attributable to emicizumab use. Tolerized participants reported the fewest joint bleeds and highest quality-of-life scores, potentially reflecting younger age and possible greater prophylaxis adherence. Emicizumab was associated with lower bleed rates compared to standard or extended half-life factor VIII products.