Surveillance colonoscopy or chemoprevention with COX-2 inhibitors in average-risk post-polypectomy patients: a decision analysis

Objectives: Clinical trials are currently underway evaluating the efficacy of COX-2 inhibitors in decreasing the incidence of adenomas and colorectal carcinoma in 'average' risk individuals. Aim: To use decision analysis to compare the cost-effectiveness of celecoxi b to surveillance colonoscopy in 'average' risk patients who had undergone prior adenoma resection. Methods: A model of the natural history of adenomas after endoscopic polype ctomy was constructed using probabilities from the literature. Cost estimat es were obtained from available Medicare reimbursement rates and supplement ed by the literature. Three strategies were evaluated: (i) no surveillance; (ii) colonoscopic surveillance; and (iii) celecoxib chemoprevention. We co mpared total costs and performed cost-effectiveness analysis between these strategies. The outcome measures were years of life saved and 'high-grade' adenoma prevented. Sensitivity analyses were performed on selected variable s. Results: Our base-case analysis assumed a 50% risk reduction in the inciden ce of adenomas among patients using cerecoxib. No surveillance was associat ed with a cost of $1014 per patient, and colonoscopic surveillance with a c ost of $1572 per patient, whereas celecoxib use was associated with a total cost of $11 503. Ten years after the index colonoscopy, 15% of patients in the no surveillance strategy developed 'high-grade' lesions compared to 13 % of patients in the colonoscopic surveillance group and 6% in the celecoxi b group. There was a small gain in years of life saved (0.006) favouring ce lecoxib over colonoscopic surveillance. The incremental cost-effectiveness ratio of celecoxib vs. colonoscopy was $141 871 per 'high-grade' adenoma pr evented and $1 715 199 per year of life saved. The most important variables in determining the cost-effectiveness of celecoxib were its cost and its e fficacy. Conclusion: Chemoprevention with COX-2 inhibitors in 'average-risk' postpol ypectomy patients is a more expensive strategy compared to colonoscopic sur veillance.