1055 — An Effectiveness and Cost-Effectiveness Analysis of Surveillance Colonoscopy in Patients with a Personal History of Adenomas

Saini SD (HSR&D - Ann Arbor VA Medical Center), Schoenfeld P (HSR&D - Ann Arbor VA Medical Center), Vijan S (HSR&D - Ann Arbor VA Medical Center)

Objectives:
Current guidelines recommend that patients with colon adenomas undergo periodic surveillance colonoscopy at a short (three-year) or long (five- to ten-year) interval based on index colonoscopy findings. The purpose of this study was to model the effectiveness and cost-effectiveness of this recommendation.

Methods:
A Markov model was developed to compare the effectiveness and cost-effectiveness of various surveillance strategies. Published literature was used to estimate polyp and cancer transition rates, risks, benefits, and costs. The target population was men and women over the age of 50 with a new diagnosis of colon adenomas. The model was calibrated to one- and three-year data from the National Polyp Study and lifetime data from the SEER registry.

Results:
In the base-case analysis, colonoscopy every three years for all patients (the 3/3 strategy) was the most effective approach, with an 83% reduction in CRC-related death compared to no surveillance at all. The incremental cost-effectiveness ratio (ICER) of this strategy was $162,000 per life-year saved (LYS) compared to the strategy suggested by current guidelines (the 3/5 strategy). The 3/5 strategy resulted in a 76% reduction in CRC-related death, with an ICER of $57,000 per LYS compared to a 3/10 strategy. The 3/10 strategy was the least effective but also the least costly of the three approaches, with an ICER of $4,500 per LYS compared to no surveillance. In sensitivity analysis, increasing the advanced adenoma miss rate from 4% (base) to 12% decreased the ICERs of the 3/3 strategy and 3/5 strategy to $79,000 and $28,000 per LYS, respectively. Decreasing the advanced adenoma transformation rate from 5% (base) to 1% increased the ICERs of both the 3/3 and the 3/5 strategies to over $100,000 per LYS.

Implications:
The surveillance strategies endorsed by current guidelines are cost-effective by traditional standards. More intensive surveillance (3/3 strategy) may be reasonable in settings where the miss rate for advanced adenomas can be expected to be high.

Impacts:
Systematic efforts should be made to implement current colon polyp surveillance guidelines in the VA Health System.