Resource Use and Costs of the Low-risk Arm of a Risk-stratified Colorectal Cancer Screening Approach Based on...

Risk-stratified colorectal cancer (CRC) screening may improve benefit-risk ratios and alleviate colonoscopy demands. Utilizing previous faecal immunochemical tests (FIT) values below positivity thresholds is promising due to its high predictive value and availability. This study aims to estimate and compare resources and costs between standard screening (SS and 2-year interval) and risk-stratified protocol (RS and 4-year interval) among low-risk participants (cumulative f-Hb ≤ 3.8 µg/g in 2 consecutive episodes) using retrospective data.

The Barcelona colorectal cancer screening programme biennially invites people aged 50 to 69 years to a FIT (cut-off point 20 µg/g). Negative results lead to reinvitation in 2 years; positive results prompt a colonoscopy appointment. Low-risk participants who underwent 2 additional screenings from 2009-2019 were considered. The SS scenario utilized real resources and costs, whereas the RS simulated outcomes using natural history probabilities. Direct screening and stage-specific CRC treatment costs were obtained.

Compared to SS, RS showed a 50% reduction in invitation letters and FITs, less than 4% reduction in nurse visits and colonoscopies, and 49 fewer low-risk and 24 fewer high-risk lesions per 100,000 screenees, with an increase in local CRC and interval cancers. The RS protocol was estimated to generate a 17.4% decrease in screening costs and a 22.6% increase in treatment costs compared to the SS, resulting in an excess cost of 8.5%.

These findings will inform the results of experimental studies, and need to be assessed in the context of the entire strategy, since the high-risk group could notably reduce treatment costs through earlier detection.