Emerging morbidities and health care resource utilization in idiopathic multicentric Castleman disease patients: A population-level analysis using health claims-based dataset.
Authors: Mukherjee Sudipto , Kanhai Karan , Kauffman David , Martin Rabecka , Paige Jeremy S , Ghosh Anirvan , Kannan Hannah , Shupo Francis , Fajgenbaum David 
Published: June 2022

e18792 Background: Idiopathic multicentric Castleman disease (iMCD) is a hematologic disorder characterized by systemic inflammation, polyclonal lymphoproliferation, and multi-organ dysfunction due to hypercytokinemia often including interleukin-6 (IL-6). iMCD patients have had historically poor outcomes, particularly prior to the advent of anti-IL-6 therapy. We recently found that ̃90% of iMCD patients did not have any claims for anti-IL-6 therapy. One potential reason for inadequate treatment is limited understanding of associated morbidities that can be controlled with therapy. We aimed to assess emergent morbidities in iMCD patients using a large administrative claims database. Methods: An iMCD cohort was identified using an administrative health claims dataset that enrolled 30.7 million US patients between January 1, 2017 and December 2, 2020. This is an updated analysis from a previously published health claims study ( Mukherjee et al, 2022). iMCD patients were identified based on CD-specific ICD-10 diagnosis code (D47·Z2), negative HHV-8 and HIV status, and diagnostic or laboratory claims for ≥2 minor criteria. Post-diagnosis hospitalizations, emergency room (ER) visits, and emergent morbidities in iMCD patients were identified in claims data and compared to non-iMCD cohort matched (1:50) by age group (0-17, 18-44, 45-54, 55-64, > 65 years), sex, insurance type, database history, and region. The iMCD cohort was further stratified by age (0-44 years, 45-60 years, > 60 years) or treatment (iMCD-directed therapy, steroid only, and no treatment) for subgroup analyses of morbidity rates. Results: We identified 271 individuals likely to have iMCD (iMCD patients) (mean age: 50·8 years; 59·4% female), including 191 patients previously reported (ASH, 2021). We found significantly higher odds of organ dysfunction (n = 116, OR = 6·5, 95% CI = 4·9, 8·5) and thrombotic events (n = 79, OR = 4·8, 95% CI = 3·4, 6·7) in iMCD patients compared to a matched non-iMCD cohort. We observed increasing proportions of morbidities with advancing age in iMCD and matched non-iMCD cohorts. Similar morbidity trends were observed in all three iMCD treatment cohorts. A high proportion of iMCD patients required an ER visit (47.8% and 42.6% in the year before and after initial diagnosis), dropping to 13.5% in the second year after diagnosis. A similar pattern was observed in inpatient stays, with a marked increase in patients hospitalized for > 5 days increasing from 6·2% two years prior to diagnosis to 34·3% and 15·6% in the two subsequent years. Conclusions: We report high odds of organ dysfunction and thrombotic events in iMCD patients from this population analysis of patient-claims data. In this iMCD cohort with previously reported low use of iMCD-directed therapies, a high proportion of patients required ER visits and inpatient hospitalizations.