Determinants of Non-Receipt of Guideline-Concordant Treatment in Pancreatic Cancer: A Classification Tree Analysis

BACKGROUND: Non-receipt of guideline-concordant treatment (GCT) in pancreatic ductal adenocarcinoma (PDAC) is associated with worse outcomes. Studies have identified associated factors, but less is known about how these factors co-occur within patient subgroups at the time of presentation to oncology care. METHODS: We conducted a retrospective cohort study of patients with PDAC treated at two academic centers. Candidate variables available at presentation were selected a priori across demographic, clinical, socioeconomic, and healthcare utilization domains. Classification and regression tree (CART) models were used to identify conditionally defined subgroups associated with non-receipt of GCT. Models were developed using an 80/20 training/test split with repeated cross-validation. RESULTS: Of 1040 patients, 337 (32.4%) did not receive GCT. In both unpruned and pruned models, Area Deprivation Index (ADI) defined the initial split. Among patients with ADI ≥7, non-receipt of GCT was more common among those entering care through the emergency department, with further stratification by race, social support, and timeliness of care. Among patients with ADI