Inpatient financial toxicity among women hospitalized with breast cancer in the United States, 2013–2022.

1555 Background: Financial toxicity is an increasingly recognized consequence of cancer care. While the outpatient costs of breast cancer are well described, national trends and drivers of inpatient financial toxicity are not well understood. We evaluated temporal trends in hospitalization volume, inflation-adjusted inpatient charges, and factors associated with high financial toxicity among women hospitalized with breast cancer in the United States. Methods: We performed a retrospective analysis of the National Inpatient Sample (2013–2022), including women aged ≥18 years with a breast cancer diagnosis. Survey weights, strata, and clusters were applied. Charges were inflation-adjusted to 2022 USD. High financial toxicity was defined as inpatient charges ≥75th percentile. Temporal trends were assessed using weighted regression, and multivariable survey-weighted logistic regression identified predictors of high financial toxicity. Results: An estimated 1. 70 million weighted hospitalizations were identified. Annual hospitalizations declined significantly (P for trend <0. 001), from 178, 660 in 2013 to 168, 630 in 2022, with a nadir in 2020. In contrast, mean inflation-adjusted inpatient charges increased by 35. 5%, from 58, 869 to 79, 797 (P for trend <0. 001), totaling more than 119. 3 billion in cumulative charges. Most hospitalizations occurred at urban teaching hospitals (71. 2%). On multivariable analysis, urban teaching (OR 3. 84, 95% CI 3. 58–4. 12) and urban non-teaching hospitals (OR 3. 53, 95% CI 3. 28–3. 79) had nearly four-fold higher odds of high financial toxicity compared with rural hospitals. Compared with White patients, Hispanic (OR 1. 53), Asian/Pacific Islander (OR 1. 44), and Black patients (OR 1. 10) had higher odds. Private insurance (OR 1. 14) and residence in the highest income quartile (OR 1. 35) were associated with increased odds, while older age was associated with lower odds. Odds of high financial toxicity increased steadily over time, peaking in 2020 (OR 1. 58) (P for trend <0. 001). Conclusions: Despite declining hospitalization rates, inpatient financial toxicity among women with breast cancer has worsened substantially, driven primarily by hospital setting and structural factors. Racial and ethnic disparities were also evident, with minority groups experiencing higher odds of high inpatient charges. These findings underscore the need for value-based strategies and policy interventions to mitigate inpatient financial burden in oncology care.