OBJECTIVES: Acute hepatic porphyria (AHP) refers to a family of rare, metabolic diseases characterized by potentially life-threatening acute attacks and, for some patients, chronic debilitating symptoms that negatively impact daily functioning and quality of life. An economic analysis of EXPLORE, the largest prospective, multinational, study in AHP patients experiencing recurrent attacks, estimated an average total of annual healthcare costs of approximately $400,000 per patient (using US cost data). This study aimed to estimate baseline healthcare resource utilization and total healthcare costs of AHP patients in ENVISION (NCT03338816), a Phase 3 global, multicenter, randomized, double-blind, placebo-controlled trial with an open label extension (OLE), evaluating the efficacy and safety of subcutaneous givosiran.

METHODS: Healthcare resource utilization data from ENVISION and unit costs of resources from publicly available U.S. sources were used to estimate annual expenditure per patient. ENVISION captured baseline attacks (prior 6 months) and use of hemin prophylaxis at study entry. The number of composite attacks (i.e. those requiring hospitalization, urgent care visit, or intravenous (IV) hemin at home) was also captured.

RESULTS: Ninety-four AHP patients enrolled, median (range) age 37.5 (19-65) years, 89% female, and median (range) of 6.5 (0.1-43) years since diagnosis. Patients had a median of 8.0 annualized composite attacks in the preceding year and 40% were on hemin prophylaxis prior to study. Estimated average annual pharmaceutical (inclusive of hemin and symptomatic treatment) and non-pharmaceutical costs (inclusive of hospitalizations and urgent care visits) per patient were $383,599 and $247,295 respectively. Estimated average annual expenditure per patient was $630,894.

CONCLUSIONS: Results from this economic analysis (direct cost only) of the ENVISION patient population at baseline demonstrated a high rate of healthcare utilization associated with a high average annual expenditure per AHP patient.