Cost-Effectiveness and National Effects of Initiating Colorectal Cancer Screening for Average-Risk Persons at Age 45 Years Instead of 50 Years

Abstract

Background & aims: The American Cancer Society has recommended initiating colorectal cancer (CRC) screening at age 45 years instead of 50 years. We estimated the cost effectiveness and national effects of adopting this recommendation.

Methods: We compared screening strategies and alternative resource allocations in a validated Markov model. We based national projections on screening participation rates by age and census data.

Results: Screening colonoscopy initiation at age 45 years instead of 50 years in 1000 persons averted 4 CRCs and 2 CRC deaths, gained 14 quality-adjusted life-years (QALYs), cost $33,900/QALY gained, and required 758 additional colonoscopies. These 758 colonoscopies could instead be used to screen 231 currently unscreened 55-year-old persons or 342 currently unscreened 65-year-old persons, through age 75 years. These alternatives averted 13-14 CRC cases and 6-7 CRC deaths and gained 27-28 discounted QALYs while saving $163,700-$445,800. Improving colonoscopy completion rates after abnormal results from a fecal immunochemical test yielded greater benefits and savings. Initiation of fecal immunochemical testing at age 45 years instead of 50 years cost $7700/QALY gained. Shifting current age-specific screening rates to 5 years earlier could avert 29,400 CRC cases and 11,100 CRC deaths over the next 5 years but would require 10.7 million additional colonoscopies and cost an incremental $10.4 billion. Improving screening rates to 80% in persons who are 50-75 years old would avert nearly 3-fold more CRC deaths at one third the incremental cost.

Conclusions: In a Markov model analysis, we found that starting CRC screening at age 45 years is likely to be cost effective. However, greater benefit, at lower cost, could be achieved by increasing participation rates for unscreened older and higher-risk persons.

Keywords: Colon Cancer; Cost-Effectiveness; Prevention; Screening.

Figure 1.

National clinical and economic outcomes of alternative age-specific screening participation scenarios by age, projected over 5 years.* Numbers in parentheses represent differences versus the comparator Scenario A (current age-specific screening participation patterns in the U.S.). *Projections are based on year 2017 census estimates (135 million people of ages 45–100), and account for age-band-specific colorectal cancer risk, and current and historical age-band-specific screening participation patterns with colonoscopy and stool-based screening. ** The 5-year projections with current participation patterns translate into approximately 139,300 colorectal cancer cases and 48,900 colorectal cancer deaths per year nationally at ages 45 and older. For comparison: (1) The estimated number of colorectal cancer cases at ages 45 and older derived from SEER data 2011–2015 and census 2017 projections is 143,500;^, (2) The estimated numbers of colorectal cancer cases and deaths at ages 45 and older based on published 2018 all-age cancer statistics (140,250 colorectal cancer cases and 50,630 colorectal cancer deaths), and the fraction of all colorectal cancers occurring at ages 45 and older (94% of all cases)^, are 132,100 and 47,700, respectively. *** Participation rates in 45–49 year-olds reflect current national data.

Figure 2.

Cost effectiveness of initiating screening at age 45 vs 50 years as a function of the average CRC risk in the population. Compared with the average risk in 1990–1994, the relative risk of 1.54 represents 45–49-year-olds today. Relative risks of 1.35, 1.18, and 0.91 represent the level of risk for persons who were 45–49 years old in 2015, 2010, and 1995, respectively. Relative risks of 0.75 and 0.50, which are, respectively, approximately one half and one third of the risk assumed for today’s 45–49-year-olds, reflect persons who may be at lower-than-average risk for colorectal cancer, whether due to environmental or heritable factors. For all scenarios, the relative risks that were modeled were assumed to apply over a lifetime, in the absence of screening. For the hybrid strategies, the comparator is the age 50–75-years component of the strategy, and for the single-modality strategies, the comparator is that modality starting at age 50 years.