Drug Patterns and Economic Costs Among Patients with Hereditary Angioedema

Background/Objectives: This study explored real-world patterns of subcutaneous (SC) long-term prophylaxis (LTP), prescriptions for on-demand treatment (ODT), and treatment-related expenditures among patients with hereditary angioedema (HAE). Methods: This study was conducted using a retrospective cohort design and US healthcare claims database (02/23/18-06/30/22). Study population included patients aged ≥12 years who initiated SC LTP with C1-esterase inhibitor (C1-INH-SC) or lanadelumab for HAE management. Study measures were evaluated from the date of LTP initiation through the last date of health plan enrollment or the study period. Study measures included LTP adherence (medication possession ratio [MPR]), LTP discontinuation (gap in drug supply ≥60 days), annualized number of ODT prescriptions, and annualized treatment-related expenditures (ie., ODT prescriptions and emergent care [all-cause hospitalizations and emergency department (ED) visits]). Measures were summarized using means, percentages, and 95% confidence intervals (CI). Results: Study population included 196 patients (C1-INH-SC: N=65; lanadelumab: N=131); mean age was 39 years and 69% were female. During a mean follow-up of 19 months, MPR for LTP was 73% (CI: 68-77) and LTP discontinuation was 48% (41-55). Mean annualized number of ODT prescriptions was 3.8 (3.6-4.1) per patient, and mean annualized treatment-related expenditures totaled $209,547 (133,460-325,453) per patient, including $200,886 (124,792-317,983) for ODT prescriptions, $7,299 (3,408-12,214) for hospitalizations and $1,363 (859-1,959) for ED visits. Conclusion: Despite the availability of SC LTP for the management of HAE, adherence was suboptimal, almost 50% of patients discontinued prophylaxis, and treatment-related expenditures were high. Notably, annualized expenditures for ODT prescriptions, hospitalizations, and ED visits averaged >$200,000, even after initiation of SC LTP.