Colorectal Cancer Screening within Colonoscopy Capacity Constraints: Can FIT-Based Programs Save More Lives by Trading off More Sensitive Test Cutoffs against Longer Screening Intervals?

Abstract

Introduction. Colorectal cancer (CRC) prevention programs using fecal immunochemical testing (FIT) in screening rely on colonoscopy for secondary and surveillance testing. Colonoscopy capacity is an important constraint. Some European programs lack sufficient capacity to provide optimal screening intensity regarding age ranges, intervals, and FIT cutoffs. It is currently unclear how to optimize programs within colonoscopy capacity constraints. Design. Microsimulation modeling, using the MISCAN-Colon model, was used to determine if more effective CRC screening programs can be identified within constrained colonoscopy capacity. A total of 525 strategies were modeled and compared, varying 3 key screening parameters: screening intervals, age ranges, and FIT cutoffs, including previously unevaluated 4- and 5-year screening intervals (using a lifetime horizon and 100% adherence). Results were compared with the policy decisions taken in Ireland to provide CRC screening within available colonoscopy capacity. Outcomes estimated net costs, quality-adjusted life-years (QALYs), and required colonoscopies. The optimal strategies within finite colonoscopy capacity constraints were identified. Results. Combining a reduced FIT cutoff of 10 µg Hb/g, an extended screening interval of 4 y and an age range of 60–72 y requires 6% fewer colonoscopies, reduces net costs by 23% while preventing 15% more CRC deaths and saving 16% more QALYs relative to a strategy (FIT 40 µg Hb/g, 2-yearly, 60–70 year) approximating current policy. Conclusion. Previously overlooked longer screening intervals may optimize cancer prevention with finite colonoscopy capacity constraints. Changes could save lives, reduce costs, and relieve colonoscopy capacity pressures. These findings are relevant to CRC screening programs across Europe that employ FIT-based testing, which face colonoscopy capacity constraints.

A Systematic Review of Cost-Effectiveness Analyses of Colorectal Cancer Screening in Europe: Have Studies Included Optimal Screening Intensities?

“…We assessed the full texts of the remaining 56 studies and 7 additional studies identified from manual reference checking. A total of 39 studies were ultimately included [ 6 , 17 , 18 , 20 – 56 ]. A PRISMA diagram is shown in Fig.…”

“…Programmes have typically used gFOBT or FIT as the primary screening test and then employ colonoscopy to triage primary screen positives. FIT has superior test sensitivity to gFOBT and the advantage of the ability to quantitatively adjust the sensitivity and specificity trade-off by varying the FIT cut-off threshold for test positivity [ 6 ]. Thus, many programmes have switched from gFOBT to FIT [ 7 ].…”

“…Like many other screening programmes, the intensity of CRC screening can be varied by adjusting the screening start age, stop age and screening interval. CRC screening is cost-effective when offered at an appropriate intensity [ 6 ]. The relevance of multiple possible alternative intervention intensities has implications for the identification of optimally cost-effective strategies that have been long recognised within cost-effectiveness analysis (CEA) [ 8 ].…”

“…Problems can arise if CEAs include insufficient strategies. A study may conclude a given strategy is cost-effective but may have failed to consider other relevant strategies, including those that are potentially more effective and cost-effective [ 6 ]. Thus, when interpreting cost-effectiveness estimates of CRC screening it is important to consider whether analyses included sufficient variation in screening age range, screening intervals and FIT cut-offs to provide the most useful policy guidance.…”

A comparison of international modelling methods to evaluate health economics of colorectal cancer screening: a systematic review protocol

“…CRC screening is subject to the World Health Organization (WHO) principles of screening, as first discussed by Wilson and Jungner [ 8 ], whereby understanding the interplay of the harms and benefits of the ability to test for the pre-clinical disease is a necessary step in health planning. Decision-makers need to consider the most cost-effective approach for their service in order to best understand whether a non-invasive diagnostic test, such as FIT, at a particular threshold, is cost-effective within a limited capacity [ 9 ]. Crucially, these screening principles have led to the application of cost-effectiveness analyses to evaluate screening and support decision-makers in their planning and delivery of services.…”