Yield of Synchronous Adenomas and Serrated Polyps in Patients With Positive Stool Tests (mt‐ <scp>sDNA</scp> or <scp>FIT</scp> ): Data From the New Hampshire Colonoscopy Registry

Background and Aims: Patients with synchronous conventional adenomas and serrated polyps are at increased risk for metachronous neoplasia. We used New Hampshire Colonoscopy Registry data to examine the prevalence, pathway, and severity of synchronous lesions detected on colonoscopy after positive multi-target-stool DNA (mt-sDNA) or Fecal Immunochemical Tests (FIT), compared to colonoscopies without prior stool test. Methods: We estimated the risk of synchronous conventional adenomas and serrated polyps relative to no lesions, adenomas only, and serrated polyps only, across the three study cohorts using multinomial logistic regression. Results: We included 1089 mt-sDNA+ patients, 436 FIT+ patients, and 43 379 patients with screening colonoscopy only without previous stool test. Patients with mt-sDNA+ tests had a higher risk of synchronous lesions compared to FIT+ patients (OR = 2.34; 95% CI: 1.70-3.28) and colonoscopy-only patients (OR = 2.92; 95% CI: 2.50-3.40). Mt-sDNA+ patients also had significantly higher risks of serrated polyps versus no polyps (RRR = 2.92; 95% CI: 2.39-3.58) and synchronous polyps versus adenomas alone (RRR = 2.00; 95% CI: 1.67-2.4) compared to colonoscopy-only patients; no such differences were found in the FIT+/colonoscopy-only comparison. Most mt-sDNA+ and FIT+ patients with synchronous lesions had at least one advanced lesion, while the majority of colonoscopy-only patients with synchronous lesions had no advanced lesion. Conclusions: The yield of synchronous conventional adenomas and serrated polyps is higher in patients with positive mt-sDNA tests compared to FIT+ or colonoscopy-only patients, likely due in part to the higher yield of serrated polyps in mt-sDNA+ patients, which persists even among patients with adenomas.