Ts virtual colonoscopy a cost-effective option to screen for colorectal cancer?

OBJECTIVE: Computed tomography (CT) or magnetic resonance (MR) colonography is a new technique that uses data generated from CT or MR imaging to creat e two- and three-dimensional scans of the colon. It has been advocated to b ecome the new primary technique of screening for colorectal cancer. The eco nomic feasibility of such recommendation, however, has not yet been evaluat ed. METHODS: The cost-effectiveness of two screening strategies using CT colono graphy or conventional colonoscopy was compared by computer models based on a Markov process. We supposed that a hypothetical population of 100,000 su bjects aged 50 yr undergoes a screening procedure every 10 yr. Suspicious f indings of CT colonography are worked-up by colonoscopy. After polypectomy, colonoscopy is repeated every 3 yr until no adenomatous polyps are found. RESULTS: Under baseline conditions, screening by CT colonography costs $24, 586 per life-year saved, compared with $20,930 spent on colonoscopy screeni ng. The incremental cost-effectiveness ratios comparing CT colonography to no screening and colonoscopy to CT colonography were $11,484 and $10,408, r espectively. Screening by colonoscopy remains more cost-effective even if t he sensitivity and specificity of CT colonography both rise to 100%. For th e two screening procedures to become similarly cost-effective, CT colonosco py needs to be associated with an initial compliance rate 15-20% better or procedural costs 54% less than colonoscopy. CONCLUSIONS: To become cost-effective and be able to compete with colonosco py in screening for colorectal cancer, CT or MR colonography would need be offered at a very low price or result in compliance rates much better than those associated with colonoscopy. (Am J Gastroenterol 1999;94:2268-2274. ( C) 1999 by Am. Coll. of Gastroenterology).