Lymphedema, characterized by disruptions to the flow of lymphatic fluid, commonly occurs in cancer survivors and has been linked to increased depression, anxiety, pain, and low healthrelated quality of life. 1 Although there is no curative treatment, patients with lymphedema may receive outpatient care to help mitigate symptoms and reduce disease progression. 2 Without proper management, lymphedema can progress to recurrent cellulitis and hospitalization. The objective of this cohort study was to identify factors associated with high costs during lymphedema-related hospitalizations.Methods | We used the Healthcare Cost and Utilization Project National Inpatient Sample to identify lymphedema-related hospitalizations. 3 All hospitalizations for lymphedema and lymphedema-associated cellulitis were included by identifying adult patients (≥18 years old) who were admitted between January 1, 2012, and December 31, 2017, with (1) a primary diagnosis of lymphedema or (2) a primary diagnosis of cellulitis with a secondary diagnosis of lymphedema. Hospitalizations were classified by disease site (upper vs lower extremity). Among patients admitted for cellulitis, codes specified the disease site; in patients admitted for lymphedema, codes specified the disease site as postmastectomy (upper extremity) or other (lower extremity). International Classification of Diseases, and International Statistical Classification of Diseases and Related Health Problems, Tenth Revision (ICD-10) codes were used for site specification. Cost to charge ratios were used to estimate reimbursed hospitalization costs. This study was considered exempt by the University of North Carolina institutional review board because the database conforms to the definition of a limited data set and no informed consent is necessary for publicly available data sets. This study followed the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) reporting guideline.The statistical analysis was performed between January 4 and June 30, 2020. Multivariable logistic regression analysis was used to estimate the association between patient, disease, and hospital characteristics and extreme costs. Extreme costs were defined as those in the top 20th percentile of costs. Multivariable generalized gamma regression analy-