Prevalence of Adenomas on Surveillance Colonoscopies for Patients with a History of Colonic Polyps of Unknown Histology.

ABSTRACT

BACKGROUND: Guidelines for surveillance colonoscopy depend on polyp histology. When patients present to a new healthcare system and report a personal history of "colon polyps," however, information on polyp histology is frequently unavailable. AIMS: To assess adenoma prevalence in patients with a history of colonic polyps of unknown histology and to compare it to patients undergoing either screening colonoscopy or surveillance colonoscopy for known adenomatous polyps. METHODS: This cohort study evaluated colonoscopies of patients ≥ 50 years of age over a 14-year period at a single institution. The exposure of interest was colonoscopy indication, categorized into three groups screening colonoscopy, surveillance colonoscopy for history of colonic polyp(s) of unknown histology, and surveillance colonoscopy for history of adenoma(s). The primary outcome was adenoma detection rate. Multivariable logistic regression was used to assess the association between colonoscopy indication and adenoma detection rate. RESULTS: Of 31,856 colonoscopies, the adenoma prevalence was 26.1% for patients undergoing screening colonoscopy, 32.9% for patients with a history of polyps of unknown histology, and 41.9% for patients with a history of known adenomatous polyps. Relative to screening colonoscopies, there were higher odds of adenoma detection in surveillance colonoscopies for polyps of unknown histology (aOR compared to screening 1.42, 95% CI 1.30-1.55) and even higher odds among surveillance colonoscopies for a history of adenoma (aOR compared to screening 1.89, 95% CI 1.75-2.05). CONCLUSION: The adenoma prevalence on surveillance colonoscopy for patients with polyps of unknown histology was higher than that of screening colonoscopies but lower than that of surveillance colonoscopies for patients with adenomatous polyps.