A decision model and cost-effectiveness analysis of colorectal cancer screening and surveillance guidelines for average-risk adults

Objectives: Guidelines for colorectal cancer screening and surveillance in people at average risk and at increased risk have recently been published b y the American Gastroenterological Association. The guidelines for the popu lation at average risk were evaluated using cost-effectiveness analyses. Methods: Since colorectal cancers primarily arise from precancerous adenoma s, a state transition model of disease progression from adenomatous polyps was developed. Rather than assuming that polyps turn to cancer after a fixe d interval (dwell time), such transitions were modeled to occur as an expon ential function of the age of the polyps. Screening strategies included per iodic fecal occult blood test, flexible sigmoidoscopy, double-contrast bari um enema, and colonoscopy. Screening costs in 1994 dollars were estimated u sing Medicare and private claims data, and clinical parameters were based u pon published studies. Results: Cost per life-year saved was $12,636 for flexible sigmoidoscopy ev ery 5 years and $14,394 for annual fecal occult blood testing. The assumpti on made for polyp dwell time critically affected the attractiveness of alte rnative screening strategies. Conclusions: Sigmoidoscopy every 5 years and annual fecal blood testing wer e the two most cost-effective strategies, but with low compliance, occult b lood testing was less cost-effective. Lowering colonoscopy costs greatly im proved the cost-effectiveness of colonoscopy every 10 years.