Inpatient outcomes among early-onset breast cancer hospitalizations with metabolic dysfunction–associated liver disease: A national estimate.

e12729 Background: The incidence of early-onset breast cancer(EOBC) continues to rise globally. Metabolic dysfunction-associated liver disease (MASLD) is prevalent in younger populations, yet its impact on inpatient outcomes among patients hospitalized with EOBC remains unknown. Methods: Using the National Inpatient Sample (2017–2022), we identified EOBC hospitalizations among patients ≤50 years with ICD-10-CM codes for invasive or in situ breast cancer (C50*, D05*). MASLD was identified using validated NIS-based algorithms. Survey-weighted multivariable regression adjusted for demographics, insurance status, sepsis, Charlson comorbidity category, and hospital characteristics. The primary outcome was all-cause in-hospital mortality; secondary outcomes included mechanical ventilation, discharge disposition, breast surgery during admission, anemia, parenteral nutrition, length of stay (LOS), and hospital costs. Results: Among 190,655 estimated EOBC hospitalizations, 4,825 (2.53%) involved MASLD. Compared with EOBC hospitalizations without MASLD, MASLD was associated with higher odds of in-hospital mortality (adjusted odds ratio [aOR] 1.74, 95% CI 1.37–2.20), mechanical ventilation (aOR 1.41, 95% CI 1.04–1.91), discharge to a facility (aOR 1.48, 95% CI 1.17–1.87), anemia (aOR 1.20, 95% CI 1.04–1.38), and the composite of death or ventilation (aOR 1.64, 95% CI 1.32–2.04; all p≤0.03). MASLD was also associated with longer LOS (~17%) and higher total charges (~8%), and lower odds of undergoing breast surgery during the index admission (aOR 0.38, 95% CI 0.29–0.51). No association was observed with parenteral nutrition. Conclusions: MASLD identifies a high-risk inpatient phenotype among patients hospitalized with EOBC, characterized by significantly greater mortality, morbidity, and resource utilization independent of overall comorbidity burden. Recognition of MASLD during hospitalization may improve risk stratification and support early multidisciplinary management. In-Hospital outcomes of EOBC hospitalizations with vs without MASLD, NIS 2017–2022. Domain Outcome MASLD Effect Estimate 95% CI p-value Cohort size EOBC hospitalizations 190,655 total — — MASLD prevalence 2.53% — — Mortality / Severity In-hospital mortality aOR 1.74 1.37–2.20 &lt;0.001 Mechanical ventilation aOR 1.41 1.04–1.91 0.027 Composite (death or ventilation) aOR 1.64 1.32–2.04 &lt;0.001 Disposition Discharge to facility/rehab aOR 1.48 1.17–1.87 0.001 Procedures Breast surgery during admission aOR 0.38 0.29–0.51 &lt;0.001 Parenteral nutrition aOR 1.08 0.87–1.35 0.46 Complications Anemia aOR 1.20 1.04–1.38 0.011 Acute kidney injury ↑ (unadjusted prevalence higher) — — Sepsis ↑ (adjusted in models) — — Venous thromboembolism ↑ (unadjusted prevalence higher) — — Resource utilization <jats:td colspan