Modeling the cost-effectiveness of colorectal cancer screening: policy guidance based on patient preferences and compliance.

BACKGROUND Obtaining regular screening exams can significantly reduce colorectal cancer (CRC) mortality. Most CRC models to date have assumed "ideal conditions" such as 100% compliance, and the effects of CRC screening tests have been assessed only under these conditions. In this study, we assess cost-effectiveness incorporating real-world patient preferences and compliance. METHODOLOGY We built an agent-based simulation model to assess the effect of compliance and patient preferences. Baseline values were derived from the 2003 and 2005 National Health Interview Survey, and effectiveness and cost parameters were obtained through literature review. Initial screening compliance was 45%, and compliance with follow-up diagnostic tests was 75%. RESULTS The current level of screening reduces CRC mortality by 44.1% when compared with no screening. Increasing diagnostic follow-up compliance to 95% can lead to an additional 9.3% reduction in CRC mortality, whereas increasing initial screening compliance to 95% can result in an additional 50.4% reduction. These increases can be achieved at a cost of about $7,500 ($1,309-$32,864) per life year saved and $14,000 ($3,620-$35,855) per life year saved for diagnostic follow-up and initial screening tests, respectively. CONCLUSIONS Increasing compliance with both initial screening test recommendation and diagnostic testing are cost-effective approaches. The most cost-effective approach under limited funding is to increase compliance with diagnostic testing for those already being screened. Targeted interventions, which are necessary to increase compliance, are generally cost-effective under the base case scenarios presented in this model, but additional studies are required to identify the most cost-effective approach.