Burden of illness among Medicare and non-Medicare US populations with acquired thrombotic thrombocytopenic purpura.

Background: Acquired thrombotic thrombocytopenic purpura (aTTP) is a rare hematologic disorder that can lead to serious life-threatening medical complications.
Objective: The aim of this study was to describe aTTP-related hospital resource utilization, cost, complications, and overall survival among US Medicare and non-Medicare populations following aTTP episodes prior to the US approval of caplacizumab.
Methods: This retrospective study utilized administrative claims data for Medicare Fee-for-Service (FFS) beneficiaries (100% sample) and a sample of commercial, managed Medicaid [MM], Medicare Advantage [MA] plan members from the Inovalon MORE ² Registry. aTTP patients ages 18+ were identified between 2010 and 2018 using a published validated algorithm: ≥1 hospitalization for thrombotic microangiopathy + therapeutic plasma exchange (TPE). 2,279 patients were identified; 65.2% were enrolled in Medicare FFS, 13.6% in commercial, 15.7% in MM, and 5.4% in MA. Mean hospitalization days for aTTP index episode ranged between 12 and 17 days; ∼60% of patients required intensive care. Mean payments for index hospitalization varied by payer [Medicare FFS: $29,024; MA: $12,860; commercial: $9,996 and MM: $10,470]. Among FFS patients, 15.7% died during initial hospitalization and 21.0% died within first 30 days of the event. During follow-up, 11.6-19.6% experienced aTTP-related exacerbation. Incidence rate of relapse and complications per 100 person-years was 5.6 [Medicare FFS: 3.6; MA: 8.7; commercial: 10.4 and MM: 14.7] and 16.7 [FFS: 15.5; MA: 20.5; commercial: 21.7 and MM: 19.1], respectively. Among Medicare patients with and without aTTP, mortality risk was 2.9 (95 % CI: 2.4-3.4) times higher for aTTP vs. non-aTTP patients.
Conclusion: This is the first real-world study evaluating burden of illness among aTTP patients in the US across payer types. Despite being treated with TPE, patients with aTTP have lower survival rates in comparison to a matched cohort without aTTP. These findings highlight the need for more effective and novel therapies to reduce disease burden for this population.Key pointsIn US Medicare and managed care populations with aTTP between 2010 and 2018, aTTP can lead to significant utilization of ICU services due to clinical complications, and/or relapse following hospital discharge.Despite treatment with therapeutic plasma exchange, acute mortality remains high (15.7%) indicating the need for more effective and novel treatments.