• A Sonnenberg, F Delcò, and J M Inadomi.
• Gastroenterologie, Kantonsspital Basel, Petersgraben 4, CH-4031 Basel, Switzerland.
• Ann. Intern. Med. 2000 Oct 17;133(8):573-84.

BackgroundFecal occult blood testing, flexible sigmoidoscopy, and colonoscopy are used to screen patients for colorectal cancer.ObjectiveTo compare the cost-effectiveness of fecal occult blood testing, flexible sigmoidoscopy, and colonoscopy.DesignThe cost-effectiveness of the three screening strategies was compared by using computer models of a Markov process. In the model, a hypothetical population of 100 000 persons 50 years of age undergoes annual fecal occult blood testing, sigmoidoscopy every 5 years, or colonoscopy every 10 years. Positive results on fecal occult blood testing or adenomatous polyps found during sigmoidoscopy are worked up by using colonoscopy. After polypectomy, colonoscopy is repeated every 3 years until no polyps are found.Data SourcesTransition rates were estimated from U.S. vital statistics and cancer statistics and from published data on the sensitivity, specificity, and efficacy of various screening techniques. Costs of screening and cancer care were estimated from Medicare reimbursement data.Target PopulationPersons 50 years of age in the general population.Time HorizonThe study population was followed annually until death.PerspectiveThird-party payer.Outcome MeasureIncremental cost-effectiveness ratio.Results Of Base Case AnalysisCompared with colonoscopy, annual screening with fecal occult blood testing costs less but saves fewer life-years. A screening strategy based on flexible sigmoidoscopy every 5 or 10 years is less cost-effective than the other two screening methods.Results Of Sensitivity AnalysisScreening with fecal occult blood testing is more sensitive to changes in compliance rates, and it becomes easily dominated by colonoscopy under most conditions assuming less than perfect compliance. Other assumptions about the sensitivity and specificity of fecal occult blood testing, screening frequency, efficacy of colonoscopy in preventing cancer, and polyp incidence have a lesser influence on the differences in cost-effectiveness between colonoscopy and fecal occult blood testing.ConclusionsColonoscopy represents a cost-effective means of screening for colorectal cancer because it reduces mortality at relatively low incremental costs. Low compliance rates render colonoscopy every 10 years the most cost-effective primary screening strategy for colorectal cancer.

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