Inpatient characteristics and outcomes among adolescent and young adult patients with metastatic breast cancer.

e23083 Background: Breast cancer is the most common cancer among adolescent and young adult (AYA) women in the US, accounting for 15% of all invasive cancers. AYA women are more likely to be diagnosed with de novo metastatic breast cancer (MBC); they also have unique cancer care needs. The characteristics of inpatient hospitalizations and outcomes in this population have not been investigated. Methods: Using the Agency for Healthcare Research and Quality (AHRQ) sponsored Healthcare Cost and Utilization Project – National Inpatient Sample (HCUP-NIS) database, we conducted a retrospective cohort analysis among female AYA MBC patients from 2016-2020. Descriptive analyses were used to compare sociodemographic and clinical characteristics between AYA and older patients. Multivariable logistic and linear regression analyses examined the association between age groups and inpatient mortality, length of stay (LOS), and hospital charges based on a 1:10 propensity score matched cohort (by race/ethnicity, hospital region, hospital location, income quartiles, insurance type, Charlson comorbidity index). Results: There were 73,873 female MBC patient hospitalizations within the 5-year period. Of these, 4,252 (5.8%) were AYA (15-39 years). The mean age was 34.6 years in the AYA group and 64.3 years in the older group. AYA patients were more likely to be Black (26.5% vs 18.1%; p < 0.001) or Hispanic (16% vs 9%; p < 0.001), obese (57.3% vs 48.3%; p < 0.001), and have private insurance (46.2% vs 30.1%, p < 0.001) or Medicaid (37.4% vs 13.3%, p < 0.001). Compared to AYA patients, older patients had a higher likelihood of being discharged to a short term/skilled nursing facility or with home health. AYA patients were less likely to have heart failure, chronic kidney disease or liver disease than older patients. Furthermore, AYA patients had lower odds of inpatient mortality (AOR: 0.83; 95% CI 0.73–0.94), shorter hospital stays (AOR: 0.88; 95% CI: 0.82–0.95) but more ICU admissions (AOR: 1.57; 95% CI 1.10–2.24) and higher total hospital charges (b: $4,431; 95% CI $1,384–$7477) relative to older patients. Conclusions: Our findings highlight distinct characteristics and hospital associated outcomes, emphasizing the need for tailored healthcare strategies to address the unique challenges faced by AYA MBC patients. Further research is needed to identify the factors driving these disparities and optimize care for this vulnerable population. Characteristics and outcomes of female AYA metastatic breast cancer patients. AYA patients Older patients p value Weighted % Obese 57.3 48.3 <0.001 Transfer to facility 8.2 20.7 <0.001 Discharged with home health 20.4 26.7 <0.001 Chemotherapy 1.5 0.6 <0.001 Radiation 0.4 0.2 0.045 AOR (95% CI) Inpatient mortality 0.83 (0.73–0.94) Ref 0.004 Length of stay >5 days 0.88 (0.82–0.95) Ref 0.001 ICU admissions 1.57 (1.10–2.24) Ref 0.012 β (95% CI) Total hospital charges 4431 (1384–7477) Ref 0.004