National patterns of hospitalization, mortality, and resource utilization in Merkel cell carcinoma in the United States, 2018–2022.

e21574 Background: Merkel cell carcinoma (MCC) is a rare, aggressive cutaneous malignancy with limited contemporary national data describing inpatient utilization and outcomes. National benchmarking of MCC-related hospitalizations may inform care delivery and resource planning. 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 MCC (ICD-10-CM C4A) were included; all analyses were conducted at the hospitalization level. National estimates incorporated discharge-level survey weights (DISCWT) with stratification by hospital stratum (NISSTRATUM) and clustering by hospital (HOSPNIS). Outcomes included hospitalization volume, admission type (elective vs non-elective), in-hospital mortality, length of stay (LOS), inflation-unadjusted hospitalization cost estimated using HCUP cost-to-charge ratios, hospital location/teaching status, and primary payer. Survey-weighted analyses accounted for the complex sampling design. Results: From 2018–2022, 308 unweighted MCC hospitalizations corresponded to an estimated 1, 535 weighted hospitalizations nationally. Elective admissions accounted for 66. 4% of hospitalizations, while 33. 6% were non-elective. Overall in-hospital mortality was 5. 3% and was higher among non-elective compared with elective admissions (8. 7% vs 0. 5%). Inpatient care was highly centralized, with 90. 9% of hospitalizations occurring at urban teaching hospitals. Medicare was the predominant payer (74. 9%), followed by private insurance (18. 2%). Mean LOS was 4. 8 days, and mean hospitalization cost was 20, 524. Conclusions: In this contemporary national sample, MCC principal hospitalizations were uncommon but associated with meaningful inpatient mortality and resource utilization. Non-elective admissions were associated with higher in-hospital mortality, and care was predominantly delivered at urban teaching hospitals with substantial reliance on Medicare coverage. These findings provide national benchmarks for inpatient MCC care and support evaluation of care delivery patterns and resource planning for this rare cutaneous malignancy.