OBJECTIVES : Routine colonoscopy is the gold standard method of colorectal cancer (CRC) screening among high-risk individuals. National clinical guidelines in Spain recommend regular screening between the age of 50 to 75 years at annual or biennial intervals. However, there is limited evidence of the cost-effectiveness of this approach. The objective of this study was to assess the long-term clinical and economic benefits of varying screening frequencies by age group among high-risk individuals.

METHODS : A Markov model simulating the natural history of individuals at high risk of CRC (N=100,000) was developed from the Spanish healthcare perspective. The model tracked patients through screening stages of CRC at diagnosis, disease progression, remission, and death. Fifteen screening strategies with varying age range and frequency were compared. Epidemiological data, clinical efficacy and cost inputs were obtained from the literature and regional public sources. Model outcomes included quality-adjusted life years (QALYs) and incremental cost-effectiveness ratio (ICER). A discount rate of 3.0% was used in the calculations.

RESULTS : Based on the net monetary benefit and a willing-to-pay threshold of €30,000 per QALY, the most cost-effective strategy was screening from age 30 to 75 years at 5-year intervals, with an ICER of €-58/QALY (i.e., less costly and larger gains in QALYs when compared to the current national strategy). Our analysis predicts a reduction of 43.8% mortality rate over the lifetime horizon when increasing the target age range to patients above 30. The parameters with the largest impact on the ICER were the upper age limit for screening, health state utility values, the cohort screening age and gender proportion.

CONCLUSIONS : This study shows that the modification of the current national screening strategy could be highly cost-effective. However, there is value in reducing the uncertainty around these cost-effectiveness estimates to better inform future screening policy.