Using VA administrative data to measure colorectal cancer screening adherence among average-risk non-elderly veterans

This study represents a new application of Veterans Affairs (VA) administrative data for measuring VA system-wide performance of colorectal cancer (CRC) screening adherence among veterans at average-risk for CRC. Our new measurement has two features: it is specifically designed for average-risk populations and is applied repeatedly at the veteran level each year over the study period. Using 1997-2007 VA administrative data, we developed an algorithm that first constructed 7 independent cohorts of average-risk veterans eligible for CRC screening, one for each year from 2001 to 2007, and then appended the seven cohorts together to form 2001-2007 veteran-level panel data. Veterans in a cohort for a given year were considered adherent if they received fecal occult blood test (FOBT) during that given year, or received flexible sigmoidoscopy (FS), double-contrast barium enema (DCBE), or colonoscopy during that given year or the 4 previous years. The main analysis shows that VA CRC screening rates increased from 30.11% in 2001 to 35.51% in 2004, but declined to 31.54% in 2007. Among the screened, the proportion adherent to colonoscopy increased over the 7-year period while the proportion adherent to FOBT, FS, or DCBE decreased during the same period. Sensitivity analyses, including use of a 10-year retrospective window for determining the screening adherence of colonoscopy, show the robustness of the main analysis. This new algorithm demonstrates that VA administrative data may be used for assessing VA performance of CRC screening adherence of average-risk veterans. Furthermore, our panel data may enhance understanding of factors associated with CRC screening adherence.