Nutritional status, cachexia, and sarcopenia as predictors of mortality in colorectal cancer: A nationwide analysis of the NIS 2016–2022.

51 Background: Malnutrition, cachexia, and sarcopenia are common in colorectal cancer (CRC) and represent overlapping syndromes of impaired nutrition and muscle loss. These conditions are associated with poorer tolerance of treatment, increased complications, and higher mortality. However, real-world, nationally representative data on their independent effects on inpatient outcomes, including mortality, mechanical ventilation, and septic shock, remain limited. Methods: Retrospective cohort of the National Inpatient Sample (2016–2022), survey-weighted to be nationally representative. Adult CRC admissions were identified by primary ICD-10 codes C18–C20. Exposures: malnutrition (E43, E44, E46), cachexia (R64), sarcopenia (M6284). Primary outcome: in-hospital mortality; secondary outcomes: mechanical ventilation (5A1935Z, 5A1945Z, 5A1955Z) and septic shock (R6521). Multivariable survey-logistic models adjusted for AKI (N17), PE (I26), febrile neutropenia (D709+R5081), diabetes (E11), CKD (N18), heart failure (I50) and demographics. We estimated total-effect models (excluding mediators) and direct-effect models (additionally adjusting for ventilation and septic shock). Results: Among ~171,700 weighted CRC admissions, malnutrition was present in 13.1%, cachexia 2.0%, and sarcopenia 0.016%. Mortality was 2.45% overall and increased by nutrition burden (0→1.7%, 1→6.4%, 2→13.0%). In adjusted total-effect models, malnutrition (aOR 2.17, 95% CI 1.98–2.38) and cachexia (aOR 3.96, 3.36–4.66) were associated with higher mortality; sarcopenia was rare and imprecise (aOR 2.87, 0.56–14.86). In direct-effect models, malnutrition remained significant (aOR 1.80, 1.62–1.99) and cachexia remained strong (aOR 4.88, 4.12–5.77). Malnutrition also predicted ventilation (aOR 2.08) and septic shock (aOR 2.61). The mortality effect of nutrition burden was attenuated but harmful in metastatic disease (interaction 0.72, p