Description:
<jats:title>Abstract</jats:title><jats:sec><jats:title>Introduction</jats:title><jats:p>The UK National Haemophilia Database (NHD) collects data from all UK persons with haemophilia A with inhibitors (PwHA‐I). It is well‐placed to investigate patient selection, clinical outcomes, drug safety and other issues not addressed in clinical trials of emicizumab.</jats:p></jats:sec><jats:sec><jats:title>Aims</jats:title><jats:p>To determine safety, bleeding outcomes and early effects on joint health of emicizumab prophylaxis in a large, unselected cohort using national registry and patient reported Haemtrack (HT) data between 01 January 2018 and 30 September 2021.</jats:p></jats:sec><jats:sec><jats:title>Methods</jats:title><jats:p>Prospectively collected bleeding outcomes were analysed in people with ≥6 months emicizumab HT data and compared with previous treatment if available. Change in paired Haemophilia Joint Health Scores (HJHS) were analysed in a subgroup. Adverse events (AEs) reports were collected and adjudicated centrally.</jats:p></jats:sec><jats:sec><jats:title>Results</jats:title><jats:p>This analysis includes 117 PwHA‐I. Mean annualised bleeding rate (ABR) was .32 (95% CI, .18; .39) over a median 42 months treatment with emicizumab. Within‐person comparison (<jats:italic>n</jats:italic> = 74) demonstrated an 89% reduction in ABR after switching to emicizumab and an increase in zero treated bleed rate from 45 to 88% (<jats:italic>p</jats:italic> < .01). In a subgroup of 37 people, total HJHS improved in 36%, remained stable in 46% and deteriorated in 18%, with a median (IQR) within‐person change of −2.0 (−9, 1.5) (<jats:italic>p</jats:italic> = .04). Three arterial thrombotic events were reported, two possibly drug related. Other AEs were generally non‐severe and usually limited to early treatment, included cutaneous reactions (3.6%), headaches (1.4%), nausea (2.8%) and arthralgia (1.4%).</jats:p></jats:sec><jats:sec><jats:title>Conclusions</jats:title><jats:p>Emicizumab prophylaxis is associated with sustained low bleeding rates and was generally well‐tolerated in people with haemophilia A and inhibitors.</jats:p></jats:sec>