The presence of more than two index adenomas is the strongest predictor of metachronous colon adenomas.

Question Under Study: To assess whether patient or adenoma characteristics at index colonoscopy could be predictors of metachronous adenomas and of advanced metachronous adenomas at first surveillance colonoscopy.
Methods: This retrospective study evaluated polypectomies of 372 adenomas in 214 patients who underwent a first follow-up colonoscopy after a median of 17 months. Logistic regression analysis was used to assess the association of baseline patient and adenoma characteristics with the development of any metachronous adenomas and of advanced adenomas (>1.0 cm, or villous component, or severe dysplasia, or early cancer).
Results: Eighty-one patients (38%) demonstrated 130 metachronous adenomas including 21 cases (10%) with advanced adenomas. The presence of more than 2 baseline adenomas was significantly associated with the finding of adenomas at follow-up (odds ratio 2.44, 95% confidence interval 1.27-4.68, p = 0.010). Patient age (>or= 60 versus <60) and size of largest adenoma (>1.0 cm versus <or= 1.0 cm) demonstrated borderline significance. However, neither gender, most advanced histology (tubulo-villous/villous versus tubular), nor most advanced dysplasia (severe/early cancer versus mild/moderate) at baseline colonoscopy were related with the development of metachronous adenomas. Furthermore, none of the analysed patient and polyp characteristics demonstrated an association with the development of advanced metachronous adenomas.
Conclusion: Patients with over 2 adenomas at baseline colonoscopy are at highest risk for the finding of adenomas at follow-up.