Cost-effectiveness of screening for colorectal cancer in the general population

Context A recent expert panel recommended that persons at average risk of c olorectal cancer (CRC) begin screening for CRC at age 50 years using 1 of s everal strategies. However, many aspects of different CRC screening strateg ies remain uncertain. Objective To assess the consequences, costs, and cost-effectiveness of CRC screening in average-risk individuals. Design Cost-effectiveness analysis from a societal perspective using a Mark ov model. Subjects Hypothetical subjects representative of the 50-year-old US populat ion at average risk for CRC. Setting Simulated clinical practice in the Uni ted States. Main Outcome Measures Discounted lifetime costs, life expectancy, and incre mental cost-effectiveness (CE) ratio, compared used 22 different CRC screen ing strategies, including those recommended by the expert panel. Results In 1 base-case analysis, compliance was assumed to be 60% with the initial screen and 80% with follow-up or surveillance colonoscopy. The most effective strategy for white men was annual rehydrated fecal occult blood testing (FOBT) plus sigmoidoscopy (followed by colonoscopy if either a low- or high-risk polyp was found) every 5 years from age 50 to 85 years, which resulted in a 60% reduction in cancer incidence and an 80% reduction in CR C mortality compared with no screening, and an incremental CE ratio of $92 900 per year of life gained compared with annual unrehydrated FOBT plus sig moidoscopy every 5 years. In a base-case analysis in which compliance with screening and follow-up is assumed to be 100%, screening more often than ev ery 10 years was prohibitively expensive; annual rehydrated FOBT plus sigmo idoscopy every 5 years had an incremental CE ratio of $489 900 per life-yea r gained compared with the same strategy every 10 years. Other strategies r ecommended by the expert panel were either less effective or cost more per year of life gained than the alternatives. Colonoscopy every 10 years was l ess effective than the combination of annual FOBI plus sigmoidoscopy every 5 years. However, a single colonoscopy at age 55 years achieves nearly half of the reduction in CRC mortality obtainable with clolonoscopy every 10 ye ars. Because of increased life expectancy among white women and increased c ancer mortality among blacks, CRC screening was even more cost-effective in these groups than in white men. Conclusions Screening for CRC, even in the setting of imperfect compliance, significantly reduces CRC mortality at rests comparable to other cancer sc reening procedures. However, compliance rates significantly affect the incr emental CE ratios. In this model of CRC, 60% compliance with an every 5-yea r schedule of screening was roughly equivalent to 100% compliance with an e very 10-year schedule. Mathematical modeling used to inform clinical guidel ines needs to take into account expected compliance rates.