Simulation modeling validity and utility in colorectal cancer screening delivery: A systematic review

OBJECTIVE

This study sought to assess the impact and validity of simulation modeling in informing decision making in a complex area of healthcare delivery: colorectal cancer (CRC) screening.

MATERIALS AND METHODS

We searched 10 electronic databases for English-language articles published between January 1, 2008, and March 1, 2019, that described the development of a simulation model with a focus on average-risk CRC screening delivery. Included articles were reviewed for evidence that the model was validated, and provided real or potential contribution to informed decision making using the GRADE EtD (Grading of Recommendations Assessment, Development, and Evaluation Evidence to Decision) framework.

RESULTS

A total of 43 studies met criteria. The majority used Markov modeling (n = 31 [72%]) and sought to determine cost-effectiveness, compare screening modalities, or assess effectiveness of screening. No study reported full model validation and only (58%) reported conducting any validation. Majority of models were developed to address a specific health systems or policy question; few articles report the model's impact on this decision (n = 39 [91%] vs. n = 5 [12%]). Overall, models provided evidence relevant to every element important to decision makers as outlined in the GRADE EtD framework.

DISCUSSION AND CONCLUSION

Simulation modeling contributes evidence that is considered valuable to decision making in CRC screening delivery, particularly in assessing cost-effectiveness and comparing screening modalities. However, the actual impact on decisions and validity of models is lacking in the literature. Greater validity testing, impact assessment, and standardized reporting of both is needed to understand and demonstrate the reliability and utility of simulation modeling.

The impact of immunochemical faecal occult blood testing on colorectal cancer incidence

BACKGROUND

The efficacy of colorectal cancer screening based on faecal immunochemical test, in terms of reduction of colorectal cancer incidence, is under debate. In the district of Florence, an organized screening programme based on faecal immunochemical test has been running since the early 1990s. The aim of this study was to compare the risk of developing colorectal cancer for subjects undergoing faecal immunochemical test with those who did not undergo the test in the same period.

METHODS

Two cohorts were analyzed: subjects who underwent an initial faecal immunochemical test between 1993 and 1999 ("attenders"), and unscreened residents in the same municipalities invited to perform the faecal immunochemical test in the same period ("non-attenders"). Kaplan-Meier and Cox regression analysis were performed to evaluate the risk of developing colorectal cancer.

RESULTS

The attenders' and non-attenders' cohorts included 6961 and 26,285 subjects, respectively. Cox analysis showed a reduction in colorectal cancer incidence of 22% in the attenders' compared to the non-attenders' cohort (hazard ratio = 0.78, 95% Confidence Interval: 0.65-0.93).

CONCLUSION

Our results support the hypothesis that screening based on a single faecal immunochemical test every 2 years produces a significant decrease in colorectal cancer incidence after an average follow-up observation period of 11 years.