National characteristics of Kaposi sarcoma–related hospitalizations and in-hospital outcomes in the United States, 2018–2022.

e23529 Background: Kaposi sarcoma (KS) is a rare malignancy predominantly affecting immunocompromised populations and may be associated with high-acuity inpatient care. Contemporary national benchmarks describing KS-related hospitalizations and outcomes are limited. Methods: A serial cross-sectional analysis of the 2018–2022 Healthcare Cost and Utilization Project National Inpatient Sample was performed. Adult (≥18 years) hospitalizations with a principal diagnosis of Kaposi sarcoma (ICD-10-CM C46) were included; all analyses were conducted at the hospitalization level. National estimates incorporated discharge-level survey weights (DISCWT) with stratification by hospital stratum (NIS_STRATUM) and clustering by hospital (HOSP_NIS). Outcomes included annual hospitalization volume, admission type (elective vs non-elective), in-hospital mortality, length of stay (LOS), and inflation-unadjusted hospitalization cost estimated using HCUP cost-to-charge ratios. Survey-weighted analyses accounted for the complex sampling design. Results: From 2018–2022, Kaposi sarcoma accounted for an estimated 315 weighted hospitalizations nationally (unweighted n=63). Annual weighted hospitalization counts were low throughout the study period, ranging from 10 to 110 admissions per year. Most KS hospitalizations were non-elective (90.5%), indicating predominantly acute or emergent presentations. Overall in-hospital mortality was approximately 16%, with similar mortality observed among elective and non-elective admissions. Mean LOS was prolonged, ranging from 9.1 to 22.1 days across study years. Hospitalization costs were substantial, exceeding $50,000 per admission on average, with year-to-year variability and wide confidence intervals reflecting small sample size. Conclusions: Kaposi sarcoma–related hospitalizations were uncommon nationally but characterized by predominantly non-elective admissions, high in-hospital mortality, prolonged LOS, and substantial inpatient costs. Despite low absolute volumes, KS represents a high-acuity and resource-intensive inpatient condition. These findings provide national benchmarks for KS-related inpatient care and support further evaluation of care delivery strategies for this rare malignancy.