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S601 Impact of FIT Performance Variability on Long-Term Colorectal Cancer Screening Outcomes: A CRC-AIM Microsimulation Analysis
Abstract   Peer reviewed

S601 Impact of FIT Performance Variability on Long-Term Colorectal Cancer Screening Outcomes: A CRC-AIM Microsimulation Analysis

Seth D Crockett, Barcey T Levy, Yinghui Xu, Chris Estes, Vahab Vahdat, Jordan Karlitz and Paul Limburg
The American journal of gastroenterology, Vol.121(10S1), pp.S130-S130
10/01/2026
DOI: 10.14309/01.ajg.0001211656.51268.95

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Abstract

Introduction: In a recent comparative evaluation of commonly used fecal immunochemical tests (FITs), the sensitivity and specificity of these tests for detecting advanced colorectal neoplasia at a single time point varied significantly. Modeling was used to assess how differences in test performance may influence screening effectiveness and downstream resource utilization over time. Methods: We used the Colorectal Cancer (CRC)-Adenoma Incidence and Mortality microsimulation model to simulate annual FIT screening from ages 45–75 years in an average-risk US population and evaluated Hemoccult ICT, Hemosure iFOB, OC-Light S FIT, QuickVue iFOB, and OC-Auto FIT. Test-specific sensitivities for precancerous lesions and CRC, along with their specificities, were incorporated into the model. Primary outcomes included reductions in CRC incidence and mortality, life-years gained (LYG), and lifetime colonoscopy burden. Secondary analyses evaluated biennial FIT screening and real-world adherence scenarios. Results: Under perfect adherence, all FITs substantially reduced CRC incidence and mortality compared with no screening. Outcomes varied considerably across tests, with annual FIT screening reducing CRC incidence by 56%–78% and CRC mortality by 64%–83%. The effectiveness gap also existed in the colonoscopy burden across FIT tests, ranging from 1,470 to 2,697 per 1,000 individuals. FITs with lower specificity were associated with higher colonoscopy burden due to increased false-positive referrals, whereas higher-specificity FITs generated fewer colonoscopies but achieved lower overall effectiveness. When screening efficiency was expressed as LYG per 1,000 colonoscopies, OC-Auto FIT and Hemoccult ICT demonstrated the highest efficiency (184 and 178 LYG/1,000 colonoscopies, respectively). Biennial screening reduced colonoscopy burden but was associated with lower LYG and a wider effectiveness gap between FITs. Sensitivity analyses incorporating real-world adherence assumptions substantially attenuated LYG across all FITs, with the greatest reductions in LYG observed among lower-sensitivity tests. Conclusion: Single-round performance characteristics vary considerably across FITs, and these differences may translate into substantial variation in long-term CRC screening effectiveness and colonoscopy burden over repeated lifetime screening. FIT performance characteristics, screening interval, and adherence meaningfully influence estimated population-level screening outcomes and resource utilization.
 Colorectal Cancer Medical Screening Colonoscopy Mortality

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