Inpatient outcomes and resource utilization by complication clustering phenotypes among colorectal cancer hospitalizations in the United States.

e23215 Background: Acute complications are common drivers of hospitalization in colorectal cancer (CRC), yet most inpatient studies evaluate individual complications in isolation. National data describing outcomes associated with co-occurring complication patterns remain limited. Methods: A serial cross-sectional analysis was performed using the 2018–2022 Healthcare Cost and Utilization Project National Inpatient Sample. Adult hospitalizations with a principal diagnosis of CRC were identified. Acute complications were ascertained from secondary diagnoses and categorized as mechanical (bowel obstruction and/or perforation), gastrointestinal bleeding, or sepsis. Hospitalizations were classified into mutually exclusive complication clustering phenotypes: none, mechanical only, bleeding only, systemic only (sepsis), mixed mechanical + sepsis, and other mixed patterns. Survey-weighted analyses estimated national prevalence, in-hospital mortality, length of stay (LOS), hospitalization cost, and discharge disposition. Survey-weighted multivariable logistic regression assessed associations between complication phenotypes and in-hospital mortality, adjusting for demographics, payer, neighborhood income quartile, hospital characteristics, and calendar year. Results: An estimated 608,685 CRC hospitalizations were identified nationally. Any acute complication occurred in 29.3% of hospitalizations. Phenotype prevalence was 70.7% with no complications, 17.7% mechanical only, 7.0% bleeding only, 1.3% systemic only, 1.6% mixed mechanical + sepsis, and 1.7% other mixed patterns. In-hospital mortality increased stepwise across phenotypes, from 1.4% without complications to 24.4% among mixed mechanical + sepsis hospitalizations. In adjusted analyses, odds of in-hospital death were markedly higher for systemic-only phenotypes (adjusted odds ratio [aOR] 17.19, 95% CI 14.74–20.05) and mixed mechanical + sepsis phenotypes (aOR 20.58, 95% CI 17.89–23.67), compared with no complications. Resource utilization increased substantially with clustering severity: mean LOS rose from 5.2 days without complications to 20.1 days in mixed mechanical + sepsis hospitalizations, while mean hospitalization cost increased from $24,054 to $83,376. Mixed phenotypes were also associated with higher rates of non-home discharge. Conclusions: Among CRC hospitalizations, complication clustering identified a small subset with markedly higher inpatient mortality and resource utilization. Although mixed and systemic phenotypes accounted for fewer than 3.5% of admissions, they contributed a disproportionate share of inpatient deaths and costs. These nationally representative findings provide benchmarking data for complication clustering as a marker of inpatient risk in colorectal cancer.