High-Intensity Versus Low-Intensity Surveillance for Patients With Colorectal Adenomas: A Cost-Effectiveness Analysis

Abstract

Background: Surveillance of patients with colorectal adenomas has limited long-term evidence to support current practice.

Objective: To compare the lifetime benefits and costs of high- versus low-intensity surveillance.

Design: Microsimulation model.

Data sources: U.S. cancer registry, cost data, and published literature.

Target population: U.S. patients aged 50, 60, or 70 years with low-risk adenomas (LRAs) (1 to 2 small adenomas) or high-risk adenomas (HRAs) (3 to 10 small adenomas or ≥1 large adenoma) removed after screening with colonoscopy or fecal immunochemical testing (FIT).

Time horizon: Lifetime.

Perspective: Societal.

Intervention: No further screening or surveillance, routine screening after 10 years, low-intensity surveillance (10 years after LRA removal and 5 years after HRA removal), and high-intensity surveillance (5 years after LRA removal and 3 years after HRA removal).

Outcome measures: Colorectal cancer (CRC) incidence and incremental cost-effectiveness.

Results of base-case analysis: Without surveillance or screening, lifetime CRC incidence for patients aged 50 years was 10.9% after LRA removal and 17.2% after HRA removal at screening colonoscopy. Subsequent colonoscopic screening, low-intensity surveillance, or high-intensity surveillance decreased incidence by 39%, 46% to 48%, and 55% to 56%, respectively. Incidence of CRC and surveillance benefits were higher for adenomas detected at FIT screening and lower for older patients. High-intensity surveillance cost less than $30 000 per quality-adjusted life-year (QALY) gained compared with low-intensity surveillance.

Results of sensitivity analysis: High-intensity surveillance cost less than $100 000 per QALY gained in most alternative scenarios for adenoma recurrence, CRC incidence, longevity, quality of life, screening ages, surveillance ages, test performance, disutilities, and cost.

Limitation: Few surveillance outcome data exist.

Conclusion: The model suggests that high-intensity surveillance as recommended in the United States provides modest but clinically relevant benefits over low-intensity surveillance at acceptable cost.

Primary funding source: National Cancer Institute.

Figure 1.

Lifetime colorectal cancer incidence in 50-year-olds with adenomas detected at screening colonoscopy or FIT * † Abbreviations: COL = colonoscopy; Cont = continued; CRC = colorectal cancer; FIT = fecal immunochemical test; HI = High-intensity; HRA = high-risk adenoma; LI = Low-intensity; LRA = low-risk adenoma; Re = return; SCR = screening; SURV = surveillance. * Low-risk adenomas were defined as 1–2 tubular adenoma <10 mm in diameter; high-risk adenomas were defined as ≥3 tubular adenoma <10mm in diameter, and/or ≥1 advanced adenoma (tubular adenoma ≥10 mm in diameter, tubulovillous adenoma, or adenoma with high-grade dysplasia). In the model histology was not described, and an advanced adenoma was considered a large adenoma. † There were four scenarios evaluated: No surveillance/No return to routine screening consisted of a baseline examination only; Return to routine screening consisted of continued colonoscopy screening after 10 years through age 70 years for colonoscopy-detected patients, and return to FIT screening through age 75 years for FIT-detected patients; Low-intensity surveillance consisted of a colonoscopy after 5 years in case of HRA detection, and colonoscopy after 10 years after detection of LRA, and 10 years or return to screening in case of no detected adenoma (Supplementary Table 1), with a stopping age of 80 years; High-intensity surveillance consisted of a colonoscopy after 3 years in case of an HRA, colonoscopy after 5 years in case of an LRA, and colonoscopy after 10 years in case of no detected adenoma in surveillance (Supplementary Table 1), with a similar stopping age of 80 years. The numbers associated with each of the scenarios are provided in Supplementary Tables 5 and 8.

Figure 2.

Sensitivity analysis of incremental cost-effectiveness ratios for surveillance in 50-year-old patients with adenoma detected at screening colonoscopy or FIT * Abbreviations: HI = high-intensity; HRA = high-risk adenoma (≥3 small adenomas or ≥1 large); LI = low-intensity; LRA = low-risk adenoma (1–2 small adenomas); QALY = quality-adjusted life year; Re = return; SCR = screening; SURV = surveillance. * Incremental cost-effectiveness for low-intensity surveillance scenarios was relative to the scenario of return to routine screening in 10 years; incremental cost-effectiveness for high-intensity surveillance was relative to low-intensity surveillance. Grey vertical lines represent the base-case ratios. Results for persons with adenomas detected by baseline screening at older ages are in Supplementary Figure 11, 13. † The recurrence of advanced adenoma at surveillance and the associated CRC risk were increased approximately three-fold to better match some of the observed data (Supplementary Figure 6, Panel d; Supplementary Figure 8). The increase was accomplished by decreasing the assumed average time it takes for a new adenoma to become large and develop into cancer. ‡ The recurrence of advanced adenoma was increased three-fold to better match observed data (Supplementary Figure 6, Panel d), but CRC risk was kept consistent with the Surveillance Epidemiology and End Results program data used for model calibration. This was accomplished by decreasing the assumed time for a new polyp to become large, but increasing the subsequent time to cancer. § Results for LRA patients were corrected for misclassification of small adenoma with advanced histological features (villous histology or high-grade dysplasia) under the assumption that these lesions behave similar to HRA. ‖ The quality of life for the population was decreased with age to reflect overall deteriorating health with age.(57)