Abstract 3569: Patient characteristics, treatment complications, and factors associated with inpatient outcomes and treatment burdens among CAR-T recipients: Insights from the 2021 National Inpatient Sample

Abstract Background: Chimeric antigen receptor T-cell (CAR-T) therapy has transformed cancer treatment since FDA approval, with increasing utilization. Despite its potential, however, inpatient CAR-T therapy remains costly and is often complicated by cytokine release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome (ICANS), leading to longer hospital stays and higher costs. Identifying factors influencing outcomes is critical for optimizing care and targeting therapy to appropriate populations. Methods: We conducted a cross-sectional study using the 2021 National Inpatient Sample (NIS). CAR-T recipients and associated complications including CRS, ICANS, and hemophagocytic lymphohistiocytosis (HLH) were identified using ICD-10 codes. The Elixhauser comorbidity index was derived from 31 comorbidities. Weighted analyses were used to provide national estimates. Generalized linear models were used to assess factors influencing length of stay (LOS) and costs, and logistic regression was employed to evaluate mortality predictors. Results: Among 6, 666, 752 weighted discharges, 525 CAR-T cases were identified, with 468 adult admissions analyzed, representing 2, 340 national encounters. The mean age was 56.1 years; most patients were White (72.4%), male (64.1%), and admitted electively (76.1%). Non-Hodgkin lymphoma (NHL) was the most common diagnosis (65.6%), followed by Multiple Myeloma (19.7%). Hospitals were predominantly large (76.9%), private (78.6%) and teaching institutions (100%). Complications included CRS (61.3%), ICANS (8.3%), and HLH (1.1%). Median LOS was 14 days (IQR: 9-19) and median charges were $980, 000 (range: $180, 000-$1, 700, 000).Higher Elixhauser comorbidity scores were associated with increased mortality (OR 1.21 per point, p < 0.01), longer LOS (+1.6 days/10-point increase, p < 0.01), and higher costs (+$91, 192/10-point increase, p < 0.01). CRS added 2.1 days to LOS (p < 0.01) and $255, 634 to costs (p = 0.003). ICANS added 2.6 days to LOS (p = 0.05) but did not significantly affect mortality. Non-Hodgkin lymphoma increased LOS by 3.5 days (p < 0.01) and costs by $1, 368, 424 (p < 0.01). Medicaid patients experienced 4.1 more days of LOS (p < 0.01). Medium-sized hospitals increased LOS by 4.2 days (p < 0.01), and large hospitals by 2.0 days (p = 0.02). Conclusions: Inpatient CAR-T therapy is associated with substantial complications, prolonged LOS, and high costs. Comorbidities, diagnosis and treatment-related complications, particularly CRS and ICANS, are primary drivers of resource utilization. Additionally, hospital size and insurance type also significantly influence outcomes. These findings highlight the need to address both clinical and non-clinical factors to optimize care delivery and patient outcomes for CAR-T therapy. Citation Format: Simo Du, Yuqing Wang, Jiahao Peng, Junmin Song, Roha Memon, Hasiya Yusuf, Ruirong Yuan, Abhishek Kumar. Patient characteristics, treatment complications, and factors associated with inpatient outcomes and treatment burdens among CAR-T recipients: Insights from the 2021 National Inpatient Sample [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 3569.