D3.439 - On-demand treatment of hereditary angioedema attacks: Assessing self-treatment, outcomes and barriers to early intervention

Hereditary angioedema(HAE) attacks are unpredictable, debilitating and potentially life-threatening. Current treatment guidelines recommend early treatment to arrest progression. Reporting attacks is crucial to guide long term prophylaxis. This study aims to describe the HAE attacks and respective treatments carried out by patients from our Department, assessing outcomes and factors that potentially limited early on-demand treatment(ODT).

Retrospective analysis of medical records from our HAE clinic for the past 12 months.

The clinical records of 81 patients were analyzed, 44 with Type I-HAE, 3 Type II and 34 HAE with normal-C1Iinhibitor. The median age was 45 years (5-80), 8 children, 54 females. During this period, 31 reported ≥1 attack, with a median of 2(1-6). A total of 73 HAE attacks were described and evaluated. The main locations were abdominal (40/54.8%), face(7/9.6%), extremities(15/20.5%), genitals(5/6.8%); 8(10.9%) were severe, 24(32.9%) moderate and 21(28.8%) mild. Stress(16.4%) and minor trauma(15.1%) were the main triggers. All patients were prescribed 2 pre-filled syringes of Icatibant(ICT) for self-administration with a written plan. Only 32.8% of attacks were treated at home with ICT, 20.5% used androgens/antifibrinolytics and 38.4% untreated. Five patients went to hospital due to attack, one after ineffective treatment with ICT while 4 did not use it. Overall, 67.1% HAE attacks were not adequately treated at home, mainly due to the mild severity and subcutaneous administration issues. Comparing HAE attacks treated and not treated at home with ICT, a statistical difference was found concerning severity (62.5% of use in severe attacks, 50%-moderate and 15%-mild,p=0.014), location (45% of use in abdominal, 27.3%-cervical/facial and 10.5%-extremities/genitals involvement,p=0.026) and duration (median of 15.2 hours-28.3 hours,p=0.003). Icatibant was completely effective or partially effective both with 45.8%. The time elapsed between symptom onset and ODT was not possible to determine.

A high rate of undertreatment was observed, including 46.9% of moderate-to-severe attacks, despite the significant burden caused by HAE attacks and the availability of effective ODT. Antifibrinolytics and androgens, not recommended for ODT, were used in 20.5%, probably due to oral administration. The study's retrospective nature and underreporting of HAE attacks, limited more detailed and robust results. The need for actions to improve patient adherence to HAE attack treatment and reporting are highlighted.