Drug Patterns and Economic Costs Among Patients with Hereditary Angioedema

Emily Kutrieb,1 Derek Weycker,1 Montserrat Vera-Llonch,2 Arthur Zbrozek,3 Kevin Ottino,1 William R Lumry4 1Avalere Health, Washington, DC, USA; 2Ionis Pharmaceuticals, Boston, MA, USA; 3Ionis Pharmaceuticals, Carlsbad, CA, USA; 4Allergy and Asthma Research Associates Research Center, Dallas, TX, USACorrespondence: Derek Weycker, Avalere Health, 1201 New York Ave NW, Washington, DC, 20005, USA, Email [email protected]/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.Plain Language Summary: Hereditary angioedema (HAE) is a rare genetic condition typically involving recurrent and unpredictable attacks of swelling that often require reactive use of on-demand treatment (ODT). Since 2017, three agents have been approved for long-term prophylaxis (LTP) of HAE attacks, including two subcutaneous agents: C1 esterase inhibitor and lanadelumab. While two prior studies evaluated the real-world clinical and economic impact of these agents, attention was limited to patients who were adherent over an extended period and thus results were unreflective of effectiveness/costs among the full population of patients initiating LTP. The present study addressed this gap by exploring real-world patterns of subcutaneous LTP, prescriptions for ODT, and healthcare expenditures among all patients with HAE initiating subcutaneous LTP, including those who were and were not adherent. From a study population comprising 196 patients followed for 19 months (on average), almost 50% discontinued LTP and expenditures for ODT remained high (>$200,000/year). Collectively, study results demonstrated suboptimal effectiveness and considerable unmet need in the management of HAE.Keywords: hereditary angioedema, clinical practice patterns, outcomes assessment, cost and cost analysis