Study Suggests Surveillance Colonoscopy is Cost-Effective for Patients at High Risk for Developing Colorectal Cancer

FINDINGS:

• A modeling study examining different surveillance strategies for patients who have adenomas on their initial screening colonoscopy found that costs and benefits differed widely depending on the characteristics of the adenomas and the surveillance intervals.
• Performing routine screening colonoscopies every ten years in patients at low risk of developing colorectal cancer (those with 1 or 2 tubular adenomas smaller than 1 cm) and surveillance colonoscopy every three years in patients at high risk (those with more frequent, larger, or advanced adenomas) was more costly, but also more effective than a “no surveillance” strategy where everyone got routine screening every ten years.
• Compared to no surveillance, which was least costly, this “3/10” strategy was highly cost-effective, with an ICER (incremental cost-effectiveness ratio) of $5,743 per QALY (quality-adjusted life year) gained.
• Compared to the 3/10 strategy, a “3/5”strategy which conducted surveillance every 5 years on low-risk patients was considerably more costly, but only marginally more effective. For example, compared to a 3/10 strategy, the 3/5 strategy resulted in five fewer cancers and one fewer cancer-related death per 1000 patients entering surveillance.
• A 3/3 strategy was cost-ineffective and potentially harmful in comparison to less intensive surveillance.
• Based on these results, the authors suggest that the 3/10 strategy is the optimal strategy under the vast majority of clinical circumstances for patients with adenomas on screening colonoscopy.

BACKGROUND:
Colorectal cancer (CRC) is thought to be the end result of a gradual, multi-step process in which the adenoma (benign tumor of glandular origin) is an intermediate stage. Patients with adenomas are at increased risk for CRC, thus guidelines recommend periodic surveillance colonoscopy. However, this practice also carries considerable monetary and resource costs, as well as the risk of procedure-related complications. In this study, a Markov model was developed to estimate the cost-effectiveness of guideline-recommended surveillance – and to determine the impact on the choice of optimal surveillance strategy in patients with newly diagnosed colonic adenomas. Four surveillance strategies were used in the model: 1) a 3/3 strategy, where all patients underwent surveillance colonoscopy every three years; 2) a 3/5 strategy, where high-risk patients underwent surveillance at a three-year interval and low-risk patients at a five-year interval; 3) a 3/10 strategy, where high-risk patients underwent colonoscopy at a three-year interval and low-risk patients at a ten-year interval; and 4) a reference strategy of no surveillance (screening colonoscopy every 10 years). For each strategy, clinical and economic outcomes were assessed, including: CRC incidence, CRC-related mortality, and QALYS (quality-adjusted life years).

LIMITATIONS:

• This was a modeling study, thus results are dependent upon the model’s structure and assumptions.
• Investigators relied heavily on National Polyp Study (NPS) data, and the risk of CRC in the NPS cohort is lower than that reported in many subsequent chemo-prevention trials.

AUTHOR/FUNDING INFORMATION:
All authors are part of HSR&D’s Center for Clinical Management Research in Ann Arbor, MI.

Saini S, Schoenfeld P, and Vijan S. Surveillance Colonoscopy is Cost-Effective for Patients with Adenomas Who are at High Risk for Colorectal Cancer. Gastroenterology March 10, 2010 [e-pub ahead of print].