(226) Healthcare Resource Utilization and Costs Before and After Diagnosis of Idiopathic Multicentric Castleman Disease in the United States

Background: : Idiopathic Multicentric Castleman Disease (iMCD) is a rare cytokine-driven hematologic disorder. Characterization of disease epidemiology is complicated by diagnostic challenges, and the economic burden of iMCD is largely undefined.

Objective: : To assess changes in healthcare resource utilization (HCRU) and costs pre- and post-diagnosis among patients with iMCD using real-world data.

Methods: : iMCD patients were identified in the MarketScan® Research Databases between January 1, 2016 and June 30, 2024. Patients were included if they had ≥1 claim for CD (ICD-10-CM diagnosis code D47.Z2) and met either (1) an algorithm incorporating established iMCD diagnostic criteria¹ or (2) predefined treatment-based criteria. Index was the date of earliest claim with a CD diagnosis. Patients with >1 claim for CD mimics post-diagnosis were excluded. Eligible patients had continuous medical and pharmacy benefits for >6 months pre- and post-index. HCRU and inpatient, outpatient, and pharmacy costs were compared pre- and post-diagnosis. Post-diagnosis iMCD-related costs—including claims with the CD diagnosis code, lymph node biopsy procedures, and CD-related therapies—were reported.

Results: : There were 114 eligible iMCD patients (mean age 49.6 years; 50% female; 85% commercially insured). In the 6-months post-diagnosis, patients were significantly more likely to have ≥1 inpatient admission compared to the 6 months prior (46.5% vs 29.0%; p=0.003); 34.0% of these admissions were iMCD-related. Use of CD-related therapies post-diagnosis was limited: 16.7% siltuximab,12.3% rituximab, 2.6% tocilizumab, and 0.9% chemotherapy. Mean (SD) all-cause healthcare costs more than doubled ($49,311 [$94,418] pre-diagnosis and $114,027 [$165,096] post-diagnosis; p< 0.001), significantly driven by higher inpatient and outpatient costs(↑$62,308; p< 0.001). Median post-diagnosis costs were also over 3x higher ($62,210 vs $19,191) versus pre-diagnosis. iMCD-related costs averaged $58,219 ($122,438), accounting for 51.1% of all-cause costs post-diagnosis, including 67.3% of outpatient and 39.3% of inpatient costs.

Conclusions: : Economic burden increased significantly during the 6-months post-diagnosis and uptake of recommended treatments remained limited. Findings underscore the need for earlier diagnosis and treatment interventions to improve disease management and reduce healthcare burden in iMCD patients.

References:
1. Noy A, Ohgami R, Munshi N et al. Blood. 2024; 144(1):797.
2. Fajgenbaum DC, Uldrick TS, Bagg A, et al. Blood. 2017;129(12):1646-1657.

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