S419 Inpatient Demographics and Outcomes of Immune Checkpoint Inhibitor-Induced Colitis: Insights From a Nationally Representative Database (2018-2022)

Introduction: Immune checkpoint inhibitors (ICIs) have become one of the most widely used treatments for various types of cancer. Complications of ICI include Immune checkpoint inhibitor-induced colitis (IIC), a significant immune-related adverse event that often necessitates hospitalization. Despite its increasing incidence, there is limited large-scale data on demographic patterns, healthcare utilization, and outcomes, particularly across different cancer subtypes. We aimed to characterize inpatient trends and outcomes of IIC using a nationally representative sample. Methods: Hospitalizations with IIC were identified using ICD-10-CM codes from the National Inpatient Sample (NIS) from 2018 to 2022. Demographic, hospital-level, and clinical variables were analyzed using weighted national estimates. Subgroup analyses were performed based on the most common cancer types receiving ICI: Non-small cell lung cancer (NSCLC), melanoma, and renal cell carcinoma (RCC). Key outcomes included mortality, sepsis, acute kidney injury (AKI), mechanical ventilation, vasopressor use, venous thromboembolism (VTE), and resource utilization. Multivariable logistic regression was used to assess associations with adverse outcomes. Results: A total of 121,220 IIC-related hospitalizations were identified. The cohort had a mean age of 62.5 years and was predominantly women (55.9%) and White (75.1%). Most patients had high comorbidity burden (Charlson Comorbidity Index ≥3 in 69.3%) and were admitted to large hospitals (56.6%). Medicare (51.6%) and private insurance (34.8%) were the most common payers. The mean length of stay was 9.3 days (95% confidence interval [CI]: 8.97–9.64), and the mean total charge was $122,376 (95% CI: $113,121–$131,631). Overall, in-hospital mortality was 2.7%. NSCLC-associated IIC was linked with the highest in-hospital mortality (12.1%) and increased odds of death (OR 4.95, P= 0.003) and VTE (OR 2.00, P= 0.003). RCC-associated IIC had the highest incidence of AKI (49.3%) and was independently associated with AKI (OR 2.46, P < 0.001). Melanoma-associated IIC showed lower comorbidity and mortality (2.2%). Acute kidney injury was found to be high in all 3 types of cancers. Conclusion: This study highlights substantial inpatient burden from ICI, particularly among patients with NSCLC and RCC. These findings underscore the need for prompt recognition, careful risk stratification, close monitoring of kidney function, and early therapeutic interventions for IIC in high-risk oncology subpopulations treated with ICI.