Disparities in colonoscopy adherence and neoplasia detection after positive fecal immunochemical test: a retrospective matched cohort study.

introductionThe fecal immunochemical test (FIT) is widely used as a first-line, noninvasive colorectal cancer (CRC) screening tool due to its convenience, affordability, and high patient adherence. However, its effectiveness depends on timely follow-up colonoscopy, and failure to complete diagnostic colonoscopy after a positive FIT can result in missed or delayed detection of precancerous lesions or CRC. It remains unclear whether FIT-based screening and subsequent follow-up are equally effective across age groups and racial and ethnic populations. This study evaluates real-world differences in colonoscopy adherence and diagnostic yield following a positive FIT and examines their implications for disparities in CRC outcomes and all-cause mortality.

methodsA retrospective cohort study was conducted using de-identified patient data from the TriNetX research network. Adult patients aged ≥ 45 years who underwent colorectal cancer screening were identified using ICD-10 codes, and positive FIT results were identified using LOINC code 29,771-3. Patients were stratified into two cohorts based on whether they had a diagnostic colonoscopy performed within 1 year of the positive FIT. The study population was further stratified into three age-based cohorts (45-50, 51-64, and 65-85 years), two ethnicity-based cohorts (Hispanic and non-Hispanic), and five race-based cohorts (White, Black, Asian, Native Hawaiian or Other Pacific Islander, and American Indian or Alaska Native). To reduce selection bias and account for potential confounders, 1:1 propensity score matching was performed using demographic characteristics and relevant comorbidities. Matched cohorts were compared using odds ratios (ORs) for colonoscopy adherence, polyp detection, and colorectal cancer detection at both the 1-year and 10-year follow-up intervals. All-cause mortality was compared between matched cohorts using hazard ratios (HRs) at the same 1-year and 10-year follow-up intervals.

resultsThe study included 45,598 adults with a positive FIT, of whom 17,727 completed colonoscopy within 1 year and 27,871 did not. After propensity score matching, 17,101 patients remained in each group. Patients who completed colonoscopy had higher CRC detection at 1 year (OR 2.401, 95% CI 1.771-3.257) and 10 years (OR 1.501, 95% CI 1.189-1.895), as well as higher polyp detection at 1 year (OR 17.610, 95% CI 16.534-18.756) and 10 years (OR 14.331, 95% CI 13.577-15.126). Colonoscopy completion was associated with lower all-cause mortality at 1 year (HR 0.604, 95% CI 0.516-0.707) and 10 years (HR 0.799, 95% CI 0.744-0.859). Adults aged 45-50 had higher colonoscopy adherence than those aged 51-64 (OR 1.214, 95% CI 1.111-1.326), while adults aged 51-64 had higher adherence than those aged 65-85 (OR 1.248, 95% CI 1.195-1.304). Hispanic patients demonstrated higher adherence than non-Hispanic patients (OR 1.686, 95% CI 1.537-1.848). Polyp detection was higher among Hispanic versus non-Hispanic patients (OR 1.165, 95% CI 1.059-1.282) and White versus Black patients (OR 1.111, 95% CI 1.026-1.202). No significant differences in CRC detection were observed across age, race, or ethnicity subgroups.

conclusionIn this large real-world cohort study, patients who underwent diagnostic colonoscopy after a positive FIT had lower all-cause mortality at both 1 and 10 years compared with those who did not. Colonoscopy adherence after a positive FIT varied by demographic group, with higher completion rates among Hispanic and Asian patients and younger adults. Polyp detection was also higher in Hispanic versus non-Hispanic patients, with no differences among age groups, while CRC detection did not vary across any subgroup. These findings highlight missed opportunities for early detection and prevention of colorectal cancer and underscore the need for targeted interventions to improve colonoscopy follow-up in lower-adherence populations.