National inpatient burden of nausea, vomiting, and dehydration during radiotherapy: A HCUP NIS analysis.

e24198 Background: Even when radiotherapy is delivered outpatient, treatment-related nausea, vomiting, and dehydration can precipitate hospitalization, driving cost and morbidity. National estimates of this burden are limited. Methods: We analyzed the HCUP National Inpatient Sample (NIS) for 2016–2022 to identify hospitalizations with radiotherapy encounters (Z51.0) and concurrent diagnoses of nausea, vomiting, or dehydration using ICD-10 codes. Outcomes included length of stay (LOS), total charges, ICU use proxies, in-hospital mortality, and non-home discharge. Survey-weighted national estimates were calculated, and multivariable regression assessed predictors including cancer site proxies, age, comorbidity burden, insurance status, income quartile, and hospital characteristics. Results: Across 7,842 weighted admissions, mean LOS was 4.6 days (SD 2.1), mean total charges $23,400 (SD $8,700), and ICU-level care proxies were required in 12% of admissions. In-hospital mortality was 0.9%, and 21% of patients required non-home discharge. Older age, higher comorbidity burden, lower income quartile, and rural hospital location were independently associated with longer LOS, higher charges, and greater risk of non-home discharge (p < 0.01). Admissions for gastrointestinal or head/neck malignancies had the highest rates of RINV-related hospitalization. Temporal trends showed stable rates over the 7-year period. Conclusions: Hospitalizations for RINV and dehydration during radiotherapy represent a measurable national burden with disparities by socioeconomic status, tumor site, and hospital location. Clinical Takeaway: Targeted outpatient supportive interventions, particularly for high-risk patients, may reduce hospitalization, costs, and morbidity during radiotherapy.