Morbidity burden and healthcare costs in idiopathic multicentric Castleman disease (BURDEN-iMCD): a retrospective population-level matched cohort analysis

AIMS: Idiopathic multicentric Castleman disease (iMCD) is a rare inflammatory hematological disorder, and real-world evidence on its clinical and economic burden is limited. We compared morbidity, healthcare resource utilization (HCRU), and costs among patients with iMCD versus matched controls and among patients with iMCD pre- versus post-diagnosis. MATERIALS AND METHODS: A retrospective cohort study was conducted (Merative MarketScan Research Databases [1 January 2016-30 June 2024]). Patients with iMCD were identified using a claims-based algorithm. Two analyses were performed. First, patients with iMCD were propensity-score matched to controls without iMCD based on demographic and clinical characteristics. Prevalences of iMCD-related morbidities were compared between patients with iMCD and controls; per-patient-per-month (PPPM) HCRU and healthcare costs were compared. Second, we conducted pre-post analyses to compare outcomes during the 6 months pre- and post-iMCD diagnosis, including receipt of iMCD-related therapy post-diagnosis. RESULTS: = 114), 29% of patients received outpatient physician-administered iMCD-related therapy post-diagnosis; 17% received siltuximab. Outcomes were significantly higher in the post- versus pre-diagnosis period. LIMITATIONS: Findings should be interpreted cautiously given potential residual confounding and limitations inherent to claims-based study designs. CONCLUSIONS: These findings suggest a high clinical and economic burden among patients with iMCD, with higher burden observed in the post-diagnosis period. Moreover, most patients were not receiving treatment and few received siltuximab, potentially indicating an unmet need.