Admission acuity and inpatient outcomes across major gastrointestinal malignancies in the United States, 2018–2022.

11097 Background: Hospitalization for gastrointestinal (GI) malignancies frequently occurs in the setting of acute decompensation or unplanned admission. National data quantifying the association between admission acuity and inpatient outcomes across major GI cancer subtypes remain limited. Methods: A serial cross-sectional analysis was conducted using the 2018–2022 Healthcare Cost and Utilization Project National Inpatient Sample. Adult hospitalizations with a principal diagnosis of esophageal (C15), gastric (C16), colorectal (C18–C20), liver or intrahepatic bile duct (C22), or pancreatic cancer (C25) were identified. Admission acuity was classified as elective or non-elective. Outcomes included in-hospital mortality (primary), length of stay (LOS), and hospitalization cost estimated using cost-to-charge ratios. National estimates accounted for survey weighting, clustering, and stratification. Survey-weighted multivariable logistic regression evaluated factors independently associated with in-hospital mortality, adjusting for admission type, cancer subtype, demographics, payer, neighborhood income quartile, hospital characteristics, and calendar year. Results: From 2018–2022, 214, 740 unweighted GI cancer hospitalizations represented an estimated 1. 07 million hospitalizations nationally. Colorectal cancer accounted for 56. 7% of admissions, followed by pancreatic (17. 6%), liver or intrahepatic bile duct (10. 5%), gastric (8. 6%), and esophageal cancer (6. 6%). Overall, 52. 9% of hospitalizations were non-elective. In-hospital mortality was higher for non-elective than elective admissions (5. 92% vs 1. 89%), with longer LOS (7. 61 vs 6. 15 days) and lower mean hospitalization costs (25, 644 vs 32, 166). In adjusted analyses, elective admission was associated with substantially lower odds of in-hospital mortality compared with non-elective admission (adjusted odds ratio aOR 0. 395; 95% CI 0. 328–0. 476). Relative to esophageal cancer, adjusted mortality odds were lower for colorectal, gastric, and pancreatic cancers, while no significant difference was observed for liver or intrahepatic bile duct cancers. Conclusions: Across major gastrointestinal malignancies, non-elective admission was associated with substantially higher inpatient mortality and longer length of stay independent of cancer subtype and sociodemographic factors. These nationally representative findings provide benchmarking data for admission acuity as a marker of inpatient risk in gastrointestinal oncology.