Background: To the authors' knowledge, few population-based studies to date have considered the serial use of colorectal cancer screening tests, which are usually recommended at specific intervals.
Methods: The study included a cohort of cancer-free Medicare beneficiaries aged >or= 70 years who were identified in 1998. Inpatient, physician, and outpatient Medicare claims for colorectal screening procedures from 1991 through 1997 and 1998 through 2004 were used to categorize patients as receiving previous and subsequent complete screening, respectively. Codes were also used to identify patients at increased neoplasia risk. Cox proportional hazards models were used to measure time to receipt of complete screening in follow-up.
Results: The cohort consisted of 153,469 Medicare beneficiaries. Previous complete screening was performed in 29.2% of the cohort, including 76.7% of the increased risk group and 22.9% of other patients (P< .001). In the entire study cohort, the criteria for complete screening during the follow-up period were met in only 25.4% of patients, and included colonoscopy (17.6%), flexible sigmoidoscopy (2.9%), yearly fecal occult blood testing (0.8%), barium enema (0.1%), and >1 method (4.1%). Subsequent screening was strongly associated with receipt of previous screening (35.7% vs 21.2% of others; P< .001), and was also more frequent in younger and white patients. The differences were maintained in multivariate analysis.
Conclusions: In a population-based cohort of Medicare beneficiaries, despite insurance reimbursement, there is significant underuse of colorectal testing. Given the ability of screening tests to reduce cancer incidence and mortality, continued efforts to promote screening are clearly warranted.