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Tarlov E, Lee TA, Weichle TW, Durazo-Arvizu R, Zhang Q, Perrin RA, Bentrem D, Hynes DM. VA and Medicare dual healthcare system use: impacts on 3-year event free survival for colon cancer. Poster session presented at: American Society of Clinical Oncology Annual Meeting; 2011 Jun 6; Chicago, IL.
Background We compared 3-year event-free survival of veterans with colon cancer who used Department of Veterans Affairs (VA) and Medicare healthcare to those who used VA only. Methods We identified veterans diagnosed with stage I, II, or III colon cancer between 1999 and 2001 in VA central tumor registry and 8 regional NCI SEER registry records. Inclusion criteria included age 66 or older and Medicare fee-for-service enrollment. We searched VA utilization and Medicare claims data for healthcare events signaling cancer relapse or progression, defined separately for each stage. Using extended Cox models, we evaluated relationships between VA-Medicare dual use and relapse/progression events. Results We identified 1,007, 1,169, and 898 patients diagnosed with stage I, II, and III colon cancer, respectively. Of those, 20%, 15%, and 11% received colon cancer care in both VA and non-VA settings. At 36 months, event-free survival rates were 84% (stage I), 53% (stage II), and 36% (stage III). Among stage I patients, dual users were twice as likely as non-dual users to experience a relapse/progression event (adjusted HR 2.01, CI95%: 1.40-2.88). African American race and distance to a VA outpatient facility greater than 4.6 miles were also associated with higher odds of a relapse/progression event. Among stage II and III patients, dual use was not associated with relapse/progression (adjusted HR 1.22, CI95%: 0.96-1.56 and HR 1.22 CI95%: 0.94-1.58, respectively). For stage II patients, older age, being unmarried, having a greater comorbidity burden, and higher tumor grade were associated with higher odds of a relapse/progression event. For stage III, patients who were older, had a greater comorbidity burden, higher tumor grade, or no adjuvant chemotherapy had higher odds of an event. Conclusions Among VA- and Medicare-eligible veterans with stage I colon cancer, dual system healthcare use was associated with increased likelihood of a clinical event suggesting cancer relapse or progression within 3 years. Understanding the specific processes by which dual use leads to cancer relapse deserve further study.