Real-World Adherence and Follow-Up Colonoscopy After Multitarget Stool DNA Screening in a Regional Healthcare System

Background Multitarget stool DNA (mt-sDNA) testing is an established noninvasive colorectal cancer (CRC) screening option for average-risk adults, but real-world completion of the screening cascade through colonoscopy remains incompletely characterized. Objectives This study aimed to evaluate mt-sDNA adherence, test positivity, and follow-up colonoscopy completion in a regional healthcare system and identify factors associated with screening cascade completion. Methods This retrospective cohort study analyzed mt-sDNA test kits ordered for average‑risk, screening‑eligible individuals in the Spartanburg Regional Healthcare System (South Carolina, USA) from January 2016 to June 2023. Analyses were conducted at the test-kit level; patients could contribute more than one eligible test during the study period. Eligible tests were from patients aged 45 to 85 years with ≥6 months of prior continuous insurance coverage and no high-risk CRC conditions. Outcomes were adherence (kit return within 365 days), test positivity among adherent test kits, and follow‑up colonoscopy within 365 days among eligible positive cases. Multivariable logistic regression and Cox proportional hazards regression models evaluated factors associated with adherence and time to colonoscopy. Results Of 8439 included test kits, 5733 (67.9%) were returned within 1 year. Among returned test kits, 1018 (17.8%) yielded a positive mt-sDNA result. Of 853 positive tests eligible for follow-up assessment, 596 (69.9%) were for patients who completed follow-up colonoscopy. Adherence to mt-sDNA testing was associated with non-Medicaid insurance, higher income, digital outreach, prior test return, and lower comorbidity burden. Time to colonoscopy was shorter for patients in the middle vs lowest income group. Discussion Medicaid insurance was the strongest insurance-related predictor of nonadherence, with rates approximately 20 percentage points below those with commercial or Medicare-type coverage. Digital outreach and prior test return history were among the independent predictors of adherence. Income was the primary independent predictor of time to follow-up colonoscopy, potentially reflecting financial barriers to diagnostic follow-up. Conclusions In this real-world cohort study, approximately two-thirds of tests were returned and 70% of eligible positive tests completed follow-up colonoscopy within 1 year. These findings identify potentially modifiable socioeconomic and outreach-related factors associated with screening cascade completion and support targeted interventions for lower-income and Medicaid-insured populations.