Colorectal Cancer: Cost-effectiveness of Colonoscopy versus CT Colonography Screening with Participation Rates and Costs

Purpose: To compare the cost-effectiveness of computed tomographic (CT) colonography and colonoscopy screening by using data on unit costs and participation rates from a randomized controlled screening trial in a dedicated screening setting. Materials and Observed participation rates and screening costs from Methods: the Colonoscopy or Colonography for Screening, or COCOS, trial were used in a microsimulation model to estimate costs and quality-adjusted life-years (QALYs) gained with colonoscopy and CT colonography screening. For both tests, the authors determined optimal age range and screening interval combinations assuming a 100% participation rate. Assuming observed participation for these combinations, the cost-effectiveness of both tests was compared. Extracolonic findings were not included because long-term follow-up data are lacking. Results: The participation rates for colonoscopy and CT colonography were 21.5% (1276 of 5924 invitees) and 33.6% (982 of 2920 invitees), respectively. Colonoscopy was more cost-effective in the screening strategies with one or two lifetime screenings, whereas CT colonography was more cost-effective in strategies with more lifetime screenings. CT colonography was the preferred test for willingness-to-pay-thresholds of €3200 per QALY gained and higher, which is lower than the Dutch willingness-to-pay threshold of €20000. With equal participation, colonoscopy was the preferred test independent of willingness-to-pay thresholds. The findings were robust for most of the sensitivity analyses, except with regard to relative screening costs and subsequent participation. Conclusion: Because of the higher participation rates, CT colonography screening for colorectal cancer is more cost-effective than colonoscopy screening. The implementation of CT colonography screening requires previous satisfactory resolution to the question as to how best to deal with extracolonic findings.