Cost-effectiveness of colorectal cancer screening with computed tomography colonography according to a polyp size threshold for polypectomy.

OBJECTIVE: Computed tomography colonography (CTC) has an acceptable accuracy in detecting colonic lesions, especially for polyps at least 6 mm. The aim of this analysis is to determine the cost-effectiveness of population-based screening for colorectal cancer (CRC) using CTC with a polyp size threshold.

METHODS: The cost-effectiveness ratios of CTC performed at 50, 60 and 70 years old, without (PL strategy) or with (TS strategy) polyp size threshold were compared using a Markov process. Incremental cost-effectiveness ratios (ICER) were calculated per life-years gained (LYG) for a time horizon of 30 years.

RESULTS: The ICER of PL and TS strategies were 12 042 and 2765 euro/LYG associated to CRC prevention rates of 37.9 and 36.5%. The ICER of PL and TS strategies dropped to 9687 and 1857 euro/LYG when advanced adenoma (AA) prevalence increased from 6.9 to 8.6% for male participants and 3.8-4.9% for female participants or to 9482 and 2067 euro/LYG when adenoma and AA annual recurrence rates dropped to 3.2 and 0.25%. The ICER for PL and TS strategies decreased to 7947 and 954 euro/LYG or when only two CTC were performed at 50 and 60-years-old. Conversely, the ICER did not significantly change when varying population participation rate or accuracy of CTC.

CONCLUSION: CTC with a 6 mm threshold for polypectomy is associated to a substantial cost reduction without significant loss of efficacy. Cost-effectiveness depends more on the AA prevalence or transition rate to CRC than on CTC accuracy or screening compliance.