title: Colorectal cancer screening in the elderly population: disparities by dual Medicare-Medicaid enrollment status.
abstract: OBJECTIVE
  To assess the disparities in colorectal cancer (CRC) screening between elderly dual Medicare-Medicaid enrollees (or duals), the most vulnerable subgroup of the Medicare population, and nonduals.
  
  
  METHODS
  The 1999 Medicare Denominator File, the Medicare Outpatient Standard Analytic Files, and Physician Supplier Part B files. In addition, the 1998 Area Resource File was used as a source for county-level attributes.
  
  
  METHODS
  CRC screening procedures for 1999-fecal occult blood test (FOBT), flexible sigmoidoscopy (FLEX), colonoscopy with FOBT and/or FLEX (COL-WFF), and colonoscopy only (COL-ONLY)-were extracted from claim records, using diagnostic and procedure codes. Duals (n = 2.5 million) and nonduals (n = 20.2 million) receiving their care through the fee-for-service system were identified from the Denominator file. Hierarchical logistic regression analysis was conducted to adjust for individual- and county-level characteristics.
  
  
  RESULTS
  Compared with nonduals, duals were disproportionately represented by female, older-old, and minority individuals (respectively 74.4 versus 58.5 percent; 19.3 versus 10.8 percent; 35.7 versus 8.0 percent), and CRC screening was significantly lower in duals than in nonduals (5.1 versus 12.2 percent for FOBT adjusted odds ratio [AOR]: 0.48, 95 percent confidence interval [CI]: 0.45-0.51); 0.7 versus 1.9 percent for FLEX, (AOR: 0.55, 95 percent CI: 0.49-0.61); 0.4 versus 0.8 percent for COL-WFF (AOR: 0.60, 95 percent CI: 0.54-0.67); and 1.8 versus 2.5 percent for COL-ONLY (AOR: 0.85, 95 percent CI: 0.80-0.89); p < .001 for all comparisons.
  
  
  CONCLUSIONS
  Duals are significantly less likely than nonduals to undergo CRC screening, even after adjusting for individual- and county-level covariates. Future studies should evaluate the contribution of comorbidity and low socioeconomic status to these disparities.
authors.affiliation: Department of Epidemiology and Biostatistics, School of Medicine, Case Western Reserve University, Cleveland, OH 44106-4945, USA.
authors.forename: Siran M
authors.initials: SM
authors.lastname: Koroukian
authors.forename: Fang
authors.initials: F
authors.lastname: Xu
authors.forename: Avi
authors.initials: A
authors.lastname: Dor
authors.forename: Gregory S
authors.initials: GS
authors.lastname: Cooper
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D015179:Colorectal Neoplasms / Q000175:diagnosis*; D003430:Cross-Sectional Studies; D005260:Female; D006302:Health Services Research; D006801:Humans; D019458:Insurance Coverage / Q000706:statistics & numerical data*; D016015:Logistic Models; D008297:Male; D008403:Mass Screening / Q000379:methods / Q000706:statistics & numerical data*; D008484:Medicaid; D006278:Medicare; D014481:United States