Efficacy and cost-effectiveness of screening colonoscopy according to the adenoma detection rate

BACKGROUND: The adenoma detection rate of the endoscopist has been related to the post-colonoscopy interval risk of colorectal cancer. OBJECTIVE: The objective of this article is to estimate the impact of adenoma detection rate on the long-term colorectal cancer prevention rate. METHODS: A Markov model was constructed to simulate the efficacy and cost of colonoscopy screening according to the adenoma detection rate of the endoscopist in 100,000 individuals. Post-colonoscopy interval colorectal cancer risk and the relative risk of interval cancer among endoscopists with different adenoma detection rates were extracted from the literature. A 1.5 relative risk was assumed between endoscopists with low and average adenoma detection rates, and a relative risk of 11 between those with average and high adenoma detection rates. Both efficacy and costs were projected over a steady-state American population. RESULTS: Screening colonoscopy performed by endoscopists with low adenoma detection rates resulted in a 7% absolute reduction in the long-term colorectal cancer incidence prevention rate as compared to the same procedure performed by those with an average adenoma detection rate (70% vs. 77%). This difference increased to 21% when comparing endoscopists with an average with those with a high adenoma detection rate. When projected on the US population, this reduced efficacy resulted in an additional 1728 and 16,123 colorectal cancer cases and the loss of $117 million and $906 million per year in the two scenarios, respectively. These estimates were sensitive to the risk of post-colonoscopy interval colorectal cancer. CONCLUSIONS: A substantial reduction in long-term colorectal cancer prevention rate may be expected when screening colonoscopy is performed by endoscopists with a suboptimal adenoma detection rate. A substantial saving may be expected when implementing policies to improve endoscopist adenoma detection rate.