Strongly Divergent Impact of Adherence Patterns on Efficacy of Colorectal Cancer Screening: The Need to Refine Adherence Statistics

Abstract

Objective The performance of colorectal cancer (CRC) screening programs depends on the adherence to screening offers. However, identical adherence levels may result from varying patterns of the population's screening behavior. We quantified the effects of different adherence patterns on the long-term performance of CRC screening for annual fecal immunochemical testing (FIT) and screening colonoscopy at ten-year intervals. Design Using a multistate Markov model, we simulated scenarios where, while at the same overall adherence level, a certain proportion of the population adheres to all screening offers ('selective' adherence) or the entire population uses the screening offers at some point(s) of time, albeit not in the recommended frequency ('sporadic' adherence). Key outcomes for comparison were the numbers of prevented CRC deaths and prevented years of potential life lost (YPLL) after 50 simulated years. Results For screening with annual FIT at adherence levels of 10-50%, ratios of prevented CRC deaths (YPLL) resulting from a sporadic versus a selective pattern ranged from 1.9-5.0 (1.9-5.0) for men and from 1.8-4.1 (1.8-4.3) for women, i.e. up to 4-5 times more CRC deaths and YPLL were prevented when the population followed a sporadic instead of a selective adherence pattern. Comparisons of simulated scenarios for screening colonoscopy revealed similar patterns. Conclusion At the same overall level of adherence, 'sporadic' adherence patterns go along with much larger preventive effects than 'selective' adherence patterns. Screening programs should prioritize efforts to reach as many people as possible at least sporadically over efforts to maximize full adherence to repeat screening offers. Adherence statistics should be refined to better reflect 'effective adherence'.

Trends of Colorectal Cancer Incidence in Kazakhstan

“…At the same time, it should be noted that according to the data of medical and preventive institutions of the Almaty region, there was no excess load of the available endoscopic equipment. Consequently, the reasons for the insufficient response and screening were not related to the material problems of the healthcare system but to low social mobilization, which was similar to the findings of a study by Heisser (2021).…”

Model based evaluation of long‐term efficacy of existing and alternative colorectal cancer screening offers: A case study for Germany

“…From a societal perspective, the assumption of a perfectly adhering population is highly unrealistic, as, in practice, full coverage to all screening and diagnostic related procedures as well as surveillance remains far out of reach even in countries with well-organized screening programs. 39,40 However, population-based adherence is a very complex matter involving differential patterns of screening behavior, for example, consistent or sporadic uptake, [41][42][43] which vary across populations, tests and considered timeframes. Analyses from the societal perspective would require comprehensive analyses going far beyond the scope of our study, which sought to address the perspective of an individual willing to undergo maximum screening and facing several possibilities, as is the case in Germany.…”

Making colonoscopy‐based screening more efficient: A “gateopener” approach

“…It was assumed that a selective proportion of subjects (ie, 25%, 50%, or 75%) adheres to screening in the recommended frequency while the remainder never uses screening ("selective adherence"). 20 The same levels of initial FIT uptake were also assumed for use of a gateopener FIT. However, as outlined above, gateopener FITs were assumed to yield a 50% positivity rate, that is, every other test will be positive (conventional biennial FIT screening was assumed to yield a positivity rate of approximately 10% 16 ).…”

“…For the same reason, when modeling conventional biennial FIT screening, we applied a "selective adherence" pattern assuming that a selective proportion of eligible subjects is fully adherent to screening in the recommended frequency whereas the remainder never uses screening. 20 Further research should address a broader range of scenarios to more precisely derive expected gains of the gateopener approach in specific screening settings.…”