Introduction: Screening for colorectal cancer (CRC) has been shown to reduce CRC incidence and mortality rates. However, effective screening requires consistent adherence beginning at the first recommended screening age. For stool-based CRC screening tests, this includes adherence to follow-up colonoscopy after an initial screening abnormal result. The objectives of this study were to (1) examine initial screening rates after turning 50 years old; (2) assess follow-up colonoscopy patterns after a positive stool-based test.
Methods: This retrospective study used administrative claims data between 1/2006 and 12/2019 for commercially insured or Medicare Advantage enrollees from a large national insurer. For objective 1, index year was the year members turned 50 years old (Post-50 cohort). For objective 2, index date was the claim date of a fecal immunochemical test (FIT) or multitarget stool DNA test (mt-sDNA) where linked lab data indicated a positive test result from the subset of members with test results available. Members were required to be continuously enrolled for 3 years prior to the index year or index date without evidence of USPSTF recommended CRC screening or diagnostic codes indicating high-risk for CRC, and for ≥1 year after the index year or date. Screening completion rates and time to follow-up colonoscopy after a positive stool-based test were assessed using the Aalen-Johansen estimator, modeling different CRC screens as competing events, and censoring individuals at the end of enrollment/observation.
Results: A total of 718,562 individuals met the Post-50 cohort criteria. Survival analysis estimated that 53% initiated CRC screening within five years after turning 50, with colonoscopy being the most common ordered test (40% cumulative rate). Among members with a known positive stool test (FIT =2,110 and mt-sDNA = 5,219), a higher % of members with the mt-sDNA test had a follow-up colonoscopy within 6 months, compared to members with a FIT test (72% vs 46%, p < 0.001). Time to follow-up colonoscopy was shorter for those with positive mt-sDNA (p< 0.001 via Mann-Whitney test); median was [58 (40-94) days] vs. [65 (39-122) days] for those with positive FIT results.
Discussion: This study indicated that there is potential for improving CRC screening among the newly eligible average-risk population, both to start screening once they reach the screening-eligible age, and to complete the CRC screening paradigm after a positive stool-based screen.
George Austin, MS1, Henrik Kowalkowski, MS1, Yinglong Guo, MS1, Lesley-Ann Miller-Wilson, PhD, MS, MBA2, Stacey Byfield, MPH, PhD1, Prat Verma, MS, MBA1, Laura Housman, MPH, MBA2, Ethan Berke, MD, MPH3. P1330 - Initial Colorectal Cancer Screenings After Turning 50 Years Old and Follow-up Screening Patterns After Positive FIT or Multitarget Stool DNA Testing Among Average-Risk Population, ACG 2021 Annual Scientific Meeting Abstracts. Las Vegas, Nevada: American College of Gastroenterology.