Reduced overall and event-free survival among colon cancer patients using dual system care

Background: Many veterans have dual Veterans Administration (VA) and Medicare healthcare coverage. We compared 3-year overall and cancer event-free survival (EFS) among patients with nonmetastatic colon cancer who obtained substantial portions of their care in both systems and those whose care was obtained predominantly in the VA or in the Medicare fee-for-service system. Methods: We conducted a retrospective observational cohort study of patients older than 65 years with stages I to III colon cancer diagnosed from 1999 to 2001 in VA and non-VA facilities. Dual use of VA and non-VA colon cancer care was categorized as predominantly VA use, dual use, or predominantly non-VA use. Extended Cox regression models evaluated associations between survival and dual use. Results: VA and non-VA users (all stages) had reduced hazard of dying compared with dual users [e.g., for stage I, VA HR 0.40, 95%confidence interval (CI): 0.28-0.56; non-VA HR 0.54, 95% CI: 0.38-0.78). For EFS, stage I findings were similar (VA HR 0.47, 95% CI: 0.35-0.62; non-VA HR 0.64, 95% CI: 0.47-0.86). Stage II and III VA users, but not non-VA users, had improved EFS (stage II: VA HR 0.74, 95% CI: 0.56-0.97; non-VA HR 0.92, 95% CI: 0.69-1.22; stage III: VA HR 0.73, 95% CI: 0.56-0.94; non-VA HR 0.81, 95% CI: 0.62-1.06). Conclusions: Improved survival among VA and non-VA compared with dual users raises questions about coordination of care and unmet needs. Impact: Additional study is needed to understand why these differences exist, why patients use both systems, and how systems may be improved to yield better outcomes in this population.