1002 — Reduced Overall and Event-Free Survival among Colon Cancer Patients Using Dual System Care
Tarlov E, Lee TA, Weichle TW, Zhang QL, and Perrin RA, Center for Management of Complex Chronic Care; Bentrem DJ, Jesse Brown VAMC; Hynes DM, Center for Management of Complex Chronic Care;
While dual VA-Medicare use has been well-documented, relatively little is known about the comparative health outcomes of Veterans who receive their care predominantly or entirely in one system and those who receive substantial portions of care in both systems. We compared 3-year overall and cancer event-free survival (OS; EFS) among patients with non-metastatic colon cancer who obtained substantial portions of care in both systems and those whose care was obtained predominantly in a single system.
In a retrospective observational cohort study of patients older than 65 years with stages I-III colon cancer diagnosed in 1999-2001 in VA and non-VA facilities, we obtained data from registry, VA workload, pharmacy, and vital status records, and Medicare claims. Patients were followed until death (OS) or a healthcare event signaling colon cancer relapse or progression (EFS). Our primary independent variable was dual use of VA and non-VA colon cancer care, constructed as a time-varying measure and categorized as 86-100% VA use (predominantly VA use), 15-85% VA use (dual use), and 0-14% VA use (predominantly non-VA use). Extended Cox models controlling for demographics, tumor grade, regional lymph nodes examined, primary and adjuvant treatment, comorbidities, healthcare use, and geographic variables estimated the association between days to event (OS and EFS) and dual use.
The cohort comprised 1,007; 1,169; and 898 patients with stage I, II, and III cancer, respectively. In adjusted models, stage I, II, and III VA users (stage I HR 0.46, CI95 [0.33–0.65]; II 0.59 [0.44-0.78]; III 0.68 [0.51-0.91]) and stage I and II non-VA users (I 0.58 [0.40–0.83]; II 0.74 [0.55-1.00]) had reduced risk of death compared to dual users. For EFS, stage I findings were similar (VA 0.51, [0.38–0.67]; non-VA 0.58 [0.43–0.79]). Stage II VA users, but not non-VA users, had improved EFS (VA 0.75 [0.58–0.98]; non-VA 0.85 [0.65–1.12]). For stage III, EFS was similar among dual and single system users.
Colon cancer patients who were dual users of VA and Medicare-covered non-VA services had worse overall and event-free survival compared to patients treated predominantly in one system. Relative decreases in survival were largest and most consistent when dual users were compared to patients who received predominantly VA care.
Our results challenge us to aggressively address dual system use in cancer care. Future improvements in VA cancer outcomes require a better understanding of why patients use both systems and what problems occur as a result. Answers to those questions will enable the development of evidence-based, testable solutions.