DRUG PATTERNS, CLINICAL OUTCOMES, AND ECONOMIC COSTS AMONG HEREDITARY ANGIOEDEMA PATIENTS INITIATING LONG-TERM PROPHYLAXIS

This study explores real-world drug use patterns, attack rates, and attack-related healthcare expenditures among patients with hereditary angioedema (HAE) initiating subcutaneous (SC) long-term prophylaxis (LTP). The study design is a retrospective cohort using US healthcare claims data (02/23/18-06/30/22). Study population included HAE patients aged > 12 years who initiated SC LTP with C1-esterase inhibitor (C1-INH-SC) or lanadelumab (berotralstat was excluded due to small sample). Study measures were evaluated from LTP initiation through loss of healthcare coverage or end of study period. Adherence was defined as medication possession ratio (MPR) and discontinuation was defined as gap in drug supply of ≥90 days. Annualized HAE attack rates and attack-related healthcare expenditures were ascertained based on hospitalizations, emergency room visits, and use of acute therapy. Analyses were descriptive. Study population included 196 patients (C1-INH-SC: N=65, mean [SD] age=37 [16] years, female=72%; lanadelumab: N=131, mean [SD] age=40 [15] years, female=68%). Mean follow-up was 18.9 months, MPR for LTP was 0.73, and LTP discontinuation was 45.7%. Mean annualized HAE attack rates were 15.7 per patient; mean annualized attack-related expenditures were $236,958 per patient. Despite availability of SC LTP, adherence was not optimal, almost 50% of patients discontinued, and attack rates and associated costs were high. Notably, the cost of attacks remained in excess of $230,000 even after initiation of SC LTP, thus demonstrating considerable unmet need in the prophylaxis of HAE attacks.