Exclusion criteria: Evaluating the impact of enrollment requirements in SEER‐Medicare research.

Background: Enrollment criteria are routinely utilized in patient selection in SEER‐Medicare but little is known about how this may be impacting research outcomes. This study evaluated demographics and survival among pancreatic cancer patients who are included and excluded from SEER‐Medicare analyses. Methods: Patients ≥66 years old with pancreatic cancer were identified (SEER‐Medicare, 2008–2015). Two patient cohorts were compared: included (continuous enrollment in Medicare Parts A and B and no enrollment in Medicare Advantage), and excluded. Mortality was assessed using a Standardized Mortality Ratio. Results: Among 49,017 patients with pancreatic cancer, 59.5% were in the included cohort. The excluded cohort was younger (median age 74 vs. 77) with more male (49.9% vs. 47.8%), non‐white (33.0% vs. 21.3%) and urban‐dwelling patients (91.0% vs. 85.0%). Those excluded had a higher mortality risk (SMR 1.06, 95%CI 1.04–1.07). Conclusions: There are significant differences in patient demographics and mortality among those who are and are not routinely included in SEER‐Medicare analyses and our study provides a critical opportunity to quantify this potential bias. [ABSTRACT FROM AUTHOR]