Endoscopists' recommendations after a false positive multitarget stool DNA test: results from a multicenter study

Organized screening programs reduce colorectal cancer (CRC)-related mortality. The multitarget stool DNA (MT-sDNA) test is approved by the U.S. Food and Drug Administration as a screening modality with good compliance and follow-up. In cases of positive MT-sDNA test results and negative colonoscopy results, experts recommend a 10-year follow-up interval. Concern about interval CRC has led to varying opinions and practices among endoscopists. The goal of our study was to determine how often endoscopists give 10-year follow-up recommendations in the setting of positive MT-sDNA test results and negative colonoscopy results.

We retrospectively identified patients who underwent an average-risk colonoscopy after a positive MT-sDNA test result. Data were collected from 4 hospitals in Southeast Michigan from August 2014 to February 2021. We excluded patients with previous colonoscopies, polyps, personal or family history of CRC, inflammatory bowel disease, and history of familial polyposis. Before analysis, we further excluded patients with procedure extent reached to less than the cecum, those whose bowel preparation was less than "excellent" or "good" according to the modified Aronchick scale, and any patient with missing or unavailable data necessary for analysis. For our secondary outcomes, we assessed predictors that may influence an endoscopist's recommendation to give a 10-year follow-up, including physician factors (ie, perceived adenoma detection rate [ADR]), years of experience, and estimated procedure volume), patient factors (ie, age, gender, comorbidities according to the Charlson index, and presence of diverticulosis), and procedural variables (ie, timing of procedure and withdrawal time). We used Fisher exact tests and multivariate logistic regression to compare recommendations to the variables collected.

We identified 689 patients who underwent a diagnostic colonoscopy after a positive MT-sDNA test result. After initial exclusion, we were left with 515 patients for analysis. Of those patients, 333 had a positive finding on colonoscopy (adenocarcinoma, advanced adenoma, or nonadvanced adenoma), and 182 patients had presumed negative colonoscopy results. After further exclusions (114 additional patients), we had 68 patients who met our strict criteria. We observed a 13% false positive rate for the MT-sDNA stool test. For the 68 patients, a 10-year follow-up interval was recommended 51% of the time and ≤5 years 21% of the time. In logistic regression analysis, older patients and patients with multiple comorbidities were more likely to receive shorter screening intervals than the standard 10 years.

Only 51% of endoscopists give 10-year follow-up recommendations in the setting of a positive MT-sDNA test result and negative colonoscopy result. Despite fewer benefits from further screening, older patients and patients with multiple comorbidities were more likely to be given shorter screening intervals after a false positive MT-sDNA result.