Colorectal cancer (CRC) screening is an important aspect of healthcare, but it is essential to take certain factors, like comorbidities, into consideration when analyzing its cost effectiveness. In traditional cost-effectiveness analysis (CEA) and effectiveness analysis, comorbidities are usually overlooked. To fill this gap, a study focused on diabetes, one of the comorbidities commonly found in elderly Americans who are over 50 years of age, and sought to investigate its impact on the health and economic outcomes of CRC screening.

The study used the Archimedes Model, which is an integrated model that encompasses diabetes, obesity, and CRC. The model created virtual people who had one or more illnesses, developed symptoms, sought care, and could receive diagnosis and treatment. The study compared various screening strategies based on different patient populations and evaluated the impact of various screening discontinuation strategies on the health and economic outcomes of colorectal cancer in patients with or without diabetes. The study assigned costs for each logistic event and allotted quality of life weights to each clinical outcome. The costs were based on 2009 Medicare reimbursement rates and Consumer Price Index (CPI). Both cost and life were discounted by 3% each year. The study defined the incremental cost-benefit ratio as the cost/quality-adjusted life year (QALY) saved in a particular strategy compared to the closest strategy in the efficient frontier.

In another study, the Microsimulation Screening Analysis-Colon Model (MISCAN-Colon) was used to evaluate the effectiveness and associated costs of screening. The study determined the proper age to stop colon endoscopy in a gender-defined cohort of 19,200 by gender, race, screening history, CRC background risk, and comorbidity status. The MISCAN-Colon quantifies the effectiveness and associated costs of screening by comparing all screened life histories with the corresponding unscreened ones. The study adjusted four different versions of MISCAN-Colon like white male, white female, black male, and black female. Gender- and race-specific data on the age, stage, and localization-peculiar incidence rate of CRC observed in the U.S. prior to the introduction of high-volume endoscopic screening (1990-1994) and information about age-specific prevalence and diversity distribution of adenomas was observed in autopsy studies.

The study defined a loss of quality of life equivalent to 2 days per colonoscopy (QALY) and 2 weeks per complication (0.0384 QALY). In CEA, the cost of colonoscopy was based on the 2007 Medicare payment rate and out-of-pocket costs. The cost of complications was gained from a cost analysis of cases of unexpected hospital use after endoscopy in 2007. The cost of life-year with CRC care was derived from the analysis of data linked to epidemiology, surveillance, and the final results of Medicare. The 2013 CPI was used to adjust all costs.

Both studies have complementary findings that shed light on different aspects of CRC screening. While the second study focused on the impact of age, race, screening history, CRC background risk, and comorbidity status on medical outcomes, the first study emphasized diabetes as a factor that affects the health and economic outcomes of CRC screening. Both studies agreed on the possibility of personalized approaches to screening increasing its overall efficiency. The first study also highlighted that the results should not be used as a basis for discontinuing screening for diabetics beyond the age of 70. Overall, these studies are crucial in understanding the effectiveness of CRC screening and the impact of comorbidities.

In regards to the limitations mentioned in the first study, it remains unclear as to how applicable the Archimedes Model, which was designed specifically for the US healthcare system, is to other countries. Additionally, while this model has undergone rigorous validation for clinical trials that are relevant to colorectal cancer, there is no guarantee that it can accurately predict events that have not been studied through empirical testing.

The second study failed to consider individuals who have had recent colonoscopy screenings with negative results, or those who have undergone multiple negative screening colonoscopies in the past. Furthermore, only colonoscopy screenings were taken into account.

Regarding policy recommendations, the growing elderly population should not be overlooked in research efforts. As such, it is recommended that research be conducted to help elderly individuals with no comorbidities, or moderate to severe comorbidities, understand the necessity of undergoing CRC screening when appropriate. This includes helping them determine the appropriate age to be screened, as well as the types of screenings they should undergo.

Additionally, surveillance recommendations for adenomatous patients should be adjusted as a means of improving current approaches. This allows elderly individuals who have previously had adenomas removed via colonoscopy to receive updated guidance.

Citations:

Dinh, T. A., Alperin, P., Walter, L. C., & Smith, R. (2012). Impact of comorbidity on colorectal cancer screening cost-effectiveness study in diabetic populations. Journal of general internal medicine, 27(6), 730–738. https://doi.org/10.1007/s11606-011-1972-6

van Hees, F., Saini, S. D., Lansdorp-Vogelaar, I., Vijan, S., Meester, R. G., de Koning, H. J., Zauber, A. G., & van Ballegooijen, M. (2015). Personalizing colonoscopy screening for elderly individuals based on screening history, cancer risk, and comorbidity status could increase cost-effectiveness. Gastroenterology, 149(6), 1425–1437. https://doi.org/10.1053/j.gastro.2015.07.042