The evaluation of rectal bleeding in adults. A cost-effectiveness analysis comparing four diagnostic strategies.

BACKGROUND: Though primary care patients commonly present with rectal bleeding, the optimal evaluation strategy remains unknown.
OBJECTIVE: To compare the cost-effectiveness of four diagnostic strategies in the evaluation of rectal bleeding.
DESIGN: Cost-effectiveness analysis using a Markov decision model. DATA SOURCES: Systematic review of the literature, Medicare reimbursement data, Surveillance, Epidemiology, and End Results (SEER) Cancer Registry. TARGET POPULATION: Patients over age 40 with otherwise asymptomatic rectal bleeding. TIME HORIZON: The patient's lifetime. PERSPECTIVE: Modified societal perspective.
INTERVENTIONS: Watchful waiting, flexible sigmoidoscopy, flexible sigmoidoscopy followed by air contrast barium enema (FS+ACBE), and colonoscopy. OUTCOME MEASURES: Incremental cost-effectiveness ratio. RESULTS OF BASE-CASE ANALYSIS: The incremental cost-effectiveness ratio for colonoscopy compared with flexible sigmoidoscopy was 5,480 dollars per quality-adjusted year of life saved (QALY). Watchful waiting and FS+ACBE were more expensive and less effective than colonoscopy. RESULTS OF SENSITIVITY ANALYSES: The cost of colonoscopy was reduced to 1,686 dollars per QALY when age at entry was changed to 45. Watchful waiting became the least expensive strategy when community procedure charges replaced Medicare costs, when age at entry was maximized to 80, or when the prevalence of polyps was lowered to 7%, but the remaining strategies provided greater life expectancy at relatively low cost. The strategy of FS+ACBE remained more expensive and less effective in all analyses. In the remaining sensitivity analyses, the incremental cost-effectiveness of colonoscopy compared with flexible sigmoidoscopy never rose above 34,000 dollars.
CONCLUSIONS: Colonoscopy is a cost-effective method to evaluate otherwise asymptomatic rectal bleeding, with a low cost per QALY compared to other strategies.