Comparison of colorectal cancer screening in veterans based on the location of primary care clinic

Objectives: To compare colorectal cancer screening rates in veterans receiving primary care (PC) in Veterans Administration (VA) community-based outpatient clinics (CBOCs) and VA medical centers (VAMCs). Methods: The VA Outpatient Care Files were used to identify 2 837 770 patients ≥50 years with ≥2 PC visits in 2010. Veterans undergoing screening/surveillance colonoscopy, sigmoidoscopy, fecal-occult-blood testing (FOBT), and double-contrast barium enema (DCBE) were identified from ICD-9-CM/CPT codes. Patients were categorized as VAMC (n = 1 403 273; 49.5%) or CBOC (1 434 497; 50.5%) based on where majority of PC encounters occurred and as high risk (n = 284 090) or average risk (n = 2 553 680) based on colorectal cancer risk factors and validated ICD-9-CM-based algorithms. Results: CBOC patients were older than VAMC (mean ages 69.3 vs 67.4 years; P <.001), more likely (P <.001) to be male (96.5% vs 95.1%), and white (67.8% vs 64.2%), but less likely to be high-risk (9.4% vs 10.5%; P <.001). Rates of colonoscopy, sigmoidoscopy, and DCBE were all lower in CBOC (P <.001). Among high-risk veterans, rates in CBOC and VAMC, respectively, were 27.4% versus 36.8% for colonoscopy, 1.3% versus 0.8% for sigmoidoscopy, and 0.8% versus 0.5% for DCBE. Among average-risk veterans, these rates were 1.3% versus 1.9%, 0.2% versus 0.1%, and 0.2% versus 0.1%, respectively. The differences remained after adjusting for age/comorbidity. The adjusted odds of colonoscopy for CBOC were 0.73 (95% confidence interval = 0.64-0.82) for average risk and 0.76 (95% confidence interval = 0.67-0.87) for high risk. In contrast, the use of FOBT was relatively similar in CBOCs and VAMCs among both high risk (11.1% vs 11.2%) and average risk (14.3% vs 14.1%). Screening rates were similar between those younger than 65 years and older than 65 years. Conclusions: Veterans receiving PC in CBOCs are less likely to receive screening colonoscopy, sigmoidoscopy, and DCBE than VAMC according to VA records. The lower use in CBOC was not offset by higher use of FOBT, including the degree to which CBOC patients may be more reliant to use non-VA services. The clinical appropriateness of these differences merits further examination.