Temporal trends, sociodemographic factors, and healthcare utilization of immune-related adverse events in hospitalized cancer patients: A national analysis, 2016-2020.

e13606 Background: Immune checkpoint inhibitors have transformed cancer treatment, but immune-related adverse events (irAEs) present significant clinical and economic challenges. We characterized temporal trends, risk factors, and healthcare utilization of irAE-related hospitalizations. Methods: Using the National Inpatient Sample (2016-2020), we identified adult patients hospitalized with adverse effects of antineoplastic/immunosuppressive drugs (ICD-10: T45.1X5) and concurrent cancer diagnoses (lung, melanoma, renal, bladder, head/neck). We classified irAE subtypes (colitis, pneumonitis, thyroiditis, hepatotoxicity, rash) and analyzed temporal trends, predictors, and clinical outcomes. Multivariable regression models adjusted for baseline comorbidity burden using the Elixhauser Comorbidity Index. Results: We identified 40,700 hospitalizations for irAEs. Mean age was 66.8 years; 53.7% were male; mean Elixhauser comorbidity score was 4.2. Lung cancer (76.1%) was most common, followed by bladder (9.5%), renal (6.6%), melanoma (5.2%), and head & neck (3.4%). Colitis was the most frequent irAE (7.89%), followed by rash (1.98%), pneumonitis (0.69%), hepatotoxicity (0.54%), and thyroiditis (0.13%). Annual irAE hospitalizations increased 14.5% from 7,133 (2016) to 8,171 (2020). Colitis prevalence increased from 6.73% to 8.82% (p < 0.001), and pneumonitis increased more than 4-fold from 0.22% to 0.97% (p < 0.001). Mean total hospital charges increased significantly from $54,520 (2016) to $66,814 (2020), representing a $3,044 annual increase (p < 0.001). Mean length of stay (LOS) remained stable at 6.0 days. After adjusting for baseline comorbidities, pneumonitis conferred the highest clinical burden with significantly longer LOS (8.2 vs 6.0 days, p < 0.001) and higher charges ($78,719 vs $60,748, p < 0.001). Paradoxically, colitis patients had $8,444 lower charges (p < 0.001) despite similar LOS. Significant racial differences were observed across multiple irAE subtypes. Black patients had 26% lower odds of colitis (OR = 0.74, p < 0.001) and 54% lower odds of rash (OR = 0.46, p < 0.001) compared to White patients. Conversely, Asian patients had lower odds of colitis (OR = 0.61, p = 0.003) but significantly higher rates of pneumonitis (OR = 1.98, p = 0.039), hepatotoxicity (OR = 2.07, p = 0.037), and rash (OR = 1.83, p = 0.002). Conclusions: As immunotherapy becomes standard of care across multiple malignancies, irAE hospitalizations increased 14.5% (2016-2020), with pneumonitis rising 4-fold. With expanding ICI utilization, healthcare systems must prepare for growing irAE burden. Notable racial differences in irAE patterns warrant further investigation to inform care delivery. These findings inform risk stratification, resource allocation, and cost projections for the growing population of ICI-treated patients.