(243) Economic burden of allogeneic hematopoietic stem cell transplantation in severe leukocyte adhesion deficiency-I: a US database study of primary immunodeficiencies

Background: : Leukocyte adhesion deficiency-I (LAD-I) is a rare primary immunodeficiency disorder (PIDD), causing life-threatening infections and inflammatory complications. Most patients present with a severe phenotype, which is associated with significant infant mortality. Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is the only current definitive treatment. However, many patients only receive best supportive care (BSC) due to donor availability and access limitations in some healthcare systems.

Objective: : Given the paucity of available data on the long-term healthcare resource use and costs of allo-HSCT for severe LAD-I, the study objective was to more broadly characterize the economic burden of patients with severe LAD-I and PIDDs.

Methods: : This retrospective database analysis uses US healthcare data from the Optum administrative claims research database (Oct 2015-Aug 2023). LAD-I has no defined ICD-10-CM diagnosis code. Patients with conditions determined suitably analogous to severe LAD-I via clinical validation were identified with ≥1 medical claim for PIDD and ≥1 claim for allo-HSCT during the study period. Date of first allo-HSCT was the index date, from which allo-HSCT costs were estimated; a 12-month pre-index period represented costs for BSC.

Results: : There were 92 patients with a severe PIDD in receipt of allo-HSCT, with a mean duration of exposure of 36 months, and a mean age of 39.3 years. Most received one transplant (82.6%) and 16 received two transplants (17.4%). Post-index, 58 experienced graft versus host disease without graft failure (63.0%), 19 experienced graft failure (20.7%), and 20 patients died in the first year following allo-HSCT (21.7%). Patients incurred $1,525,864 in mean all-cause healthcare costs, mainly from an inpatient setting ($1,000,232; 65.6%). Patients incurred mean costs of $487,538 (32.0% of total costs) during the pre-index year (under BSC), with the first-year post-index associated with the greatest cost ($815,041; 53.4%), primarily within the first 100 days ($538,612; 35.3%). Estimated costs were higher if exposure-adjusted, and/or stratified by age or by transplant-related complications.

Conclusions: : PIDDs such as severe LAD-I exert a substantial burden on the US healthcare system. Allo-HSCT is associated with significant long-term costs and HCRU, especially in younger patients and those experiencing transplant-related complications. An unmet need exists for therapies that avoid transplant-related inpatient care, morbidity and mortality.

Sponsorship:: Rocket Pharmaceuticals, Inc.