Stool DNA testing to screen for colorectal cancer in the Medicare population: a cost-effectiveness analysis

Abstract

Background: The Centers for Medicare & Medicaid Services considered whether to reimburse stool DNA testing for colorectal cancer screening among Medicare enrollees.

Objective: To evaluate the conditions under which stool DNA testing could be cost-effective compared with the colorectal cancer screening tests currently reimbursed by the Centers for Medicare & Medicaid Services.

Design: Comparative microsimulation modeling study using 2 independently developed models.

Data sources: Derived from literature.

Target population: A cohort of persons aged 65 years. A sensitivity analysis was also conducted, in which a cohort of persons aged 50 years was studied.

Time horizon: Lifetime.

Perspective: Third-party payer.

Intervention: Stool DNA test every 3 or 5 years in comparison with currently recommended colorectal cancer screening strategies.

Outcome measures: Life expectancy, lifetime costs, incremental cost-effectiveness ratios, and threshold costs.

Results of base-case analysis: Assuming a cost of $350 per test, strategies of stool DNA testing every 3 or 5 years yielded fewer life-years and higher costs than the currently recommended colorectal cancer screening strategies. Screening with the stool DNA test would be cost-effective at a per-test cost of $40 to $60 for stool DNA testing every 3 years, depending on the simulation model used. There were no levels of sensitivity and specificity for which stool DNA testing would be cost-effective at its current cost of $350 per test. Stool DNA testing every 3 years would be cost-effective at a cost of $350 per test if the relative adherence to stool DNA testing were at least 50% better than that with other screening tests.

Results of sensitivity analysis: None of the results changed substantially when a cohort of persons aged 50 years was considered.

Limitation: No pathways other than the traditional adenoma-carcinoma sequence were modeled.

Conclusion: Stool DNA testing could be a cost-effective alternative for colorectal cancer screening if the cost of the test substantially decreased or if its availability would entice a large fraction of otherwise unscreened persons to receive screening.

Figure 1

Panel A: MISCAN Panel B: SimCRC Discounted costs and discounted life-years gained per 1,000 65-year-olds for 18 colorectal cancer screening strategies and the efficient frontier connecting the efficient strategies. Discounted costs and life-years reflect total costs and life-years gained of a screening program, accounting for time preference for present over future outcomes. Life-years gained are plotted on the y axis, and total costs are plotted on the x axis. Each possible screening strategy is represented by a point.(50) Strategies that form the solid line connecting the points lying left and upward are the economically rational subset of choices. This line is called the efficient frontier. The inverse slope of the line represents the incremental cost-effectiveness ratio of the connected strategies (values presented in Appendix 3). Points lying to the right and beneath the line represent the dominated strategies. Stool DNA testing has higher costs and fewer life-years gained than Hemoccult SENSA and the stool DNA strategies are therefore strongly dominated. Abbreviations: y, years; HII, annual Hemoccult II; HS, annual Hemoccult SENSA; IFOBT, annual immunochemical fecal occult blood test; SIGB, 5-yearly sigmoidoscopy with biopsy; SIG, 5-yearly sigmoidoscopy without biopsy; HS (3y) = 3-yearly Hemoccult SENSA; iFOBT (3y) = 3-yearly immunochemical fecal occult blood test; COL, 10-yearly colonoscopy.

Figure 1

Panel A: MISCAN Panel B: SimCRC Discounted costs and discounted life-years gained per 1,000 65-year-olds for 18 colorectal cancer screening strategies and the efficient frontier connecting the efficient strategies. Discounted costs and life-years reflect total costs and life-years gained of a screening program, accounting for time preference for present over future outcomes. Life-years gained are plotted on the y axis, and total costs are plotted on the x axis. Each possible screening strategy is represented by a point.(50) Strategies that form the solid line connecting the points lying left and upward are the economically rational subset of choices. This line is called the efficient frontier. The inverse slope of the line represents the incremental cost-effectiveness ratio of the connected strategies (values presented in Appendix 3). Points lying to the right and beneath the line represent the dominated strategies. Stool DNA testing has higher costs and fewer life-years gained than Hemoccult SENSA and the stool DNA strategies are therefore strongly dominated. Abbreviations: y, years; HII, annual Hemoccult II; HS, annual Hemoccult SENSA; IFOBT, annual immunochemical fecal occult blood test; SIGB, 5-yearly sigmoidoscopy with biopsy; SIG, 5-yearly sigmoidoscopy without biopsy; HS (3y) = 3-yearly Hemoccult SENSA; iFOBT (3y) = 3-yearly immunochemical fecal occult blood test; COL, 10-yearly colonoscopy.

Figure 2

Stool DNA unit test cost thresholds at which the stool DNA strategies are efficient screening options compared with other reimbursed colorectal cancer screening strategies for different combinations of stool DNA test sensitivity and specificity. All sensitivities and the specificity for stool DNA were improved from their baseline value up to 100%; the % on the x-axis represents the relative improvement over that interval, the absolute improvement varies depending on the baseline value for sensitivity and specificity.

Figure 3

Stool DNA unit test cost thresholds at which the stool DNA strategies are efficient screening options compared with other reimbursed colorectal cancer screening strategies for different levels of adherence with stool DNA screening. Adherence for stool DNA was improved from its baseline value of 57% up to 100%; the % on the x-axis represents the relative improvement over that interval.