Annual Scientific Meeting
Introduction: Studies using standard definition colonoscopes in the early 2000s demonstrated the risk of metachronous advanced neoplasia (MAN) was doubled in patients with >3 vs 1-2 small tubular adenomas. In the last decade, attention to the importance of adenoma detection rate and the use of high definition (HD) colonoscopes, increases small adenoma detection. We analyzed the association between baseline adenoma features, particularly multiplicity of non-advanced adenomas, on the risk of MAN in patients undergoing HD colonoscopy.
Methods: Patients undergoing first colonoscopy at age ≥50 in the era of HD colonoscopes ( ≥2006) and follow-up colonoscopy >24 months from baseline exam were identified from the electronic medical record. Exclusions included inflammatory bowel disease, history of colorectal cancer or colon surgery, incomplete colonoscopy, and inadequate bowel preparation. High risk adenoma (HRA) patients included those with an advanced adenoma ( ≥10mm in size, adenoma with villous features/ high-grade dysplasia) or ≥3 adenomas. Low risk adenoma (LRA) patients included those with 1-2, < 10 mm tubular adenomas. The risk of MAN was calculated according to baseline adenoma features. Multivariable analysis compared the risk of MAN between individuals with LRA vs HRA on baseline HD colonoscopy adjusted for interval between first and follow-up colonoscopies.
Results: 159,273 patients underwent colonoscopy at age ≥50 in 2006 or later. After exclusions, 3,383 were included. Mean age was 60.5±7.8 and 54.6% were females. The median time interval between the first and follow-up colonoscopy was 59.9 (42.5-66.7) months for the LRA group and 41.8 (36.3-52.2) months for the HRA group. The risk of MAN was 3.8% in individuals with no baseline adenomas; 4% with LRA; and 9.2% with HRA. The risk of MAN in individuals with >3 non-advanced adenomas was 6.3%; 6.1% with 3-4 and 7.4% with > 5 non-advanced adenomas (Table 1). On multivariable analysis, the risk of MAN was not different between HRA and LRA based upon the number of non-advanced adenomas: > 3 [OR 1.6, (0.7, 3.9)]; 3-4 [OR 1.6, (0.61, 4.0)] and > 5 non-advanced adenomas [OR 2.2, (0.27, 17.0)] (Table 2).
Discussion: In the contemporary era of HD colonoscopy, compared to LRA patients, patients with ≥3 non-advanced adenomas are not at increased risk of MAN including patients with 3-4 and ≥5 non-advanced adenomas. These data support a longer colonoscopy interval ( > 5 years) in these individuals.