Introduction: The National Polyp Study demonstrated that removal of adenomas with at least a three-year follow up reduced the incidence of colorectal cancer. However, compliance with follow up colonoscopy may affect the estimates of reduction in colorectal cancer incidence demonstrated by the National Polyp Study. While an 80% compliance rate for follow up colonoscopy was achieved during the National Polyp Study, the compliance rate for follow up colonoscopy is unknown in the general population. The aim of this study was to determine the compliance rate for follow up colonoscopy and factors which affect follow up.
Methods: A retrospective medical record review to identify patients who had adenomatous polyps excised in 1997 was undertaken. Patients who had inflammatory bowel disease, a prior history of colorectal cancer, familial adenomatous polyposis syndrome, colonic surgery; incomplete polypectomy or incomplete colonoscopy, and those patients who died before planned follow up, were excluded from analysis. Follow up was performed by telephone survey.
Results: Three hundred and thirty-three patients were identified (196 males; 147 females) with a mean age of 70 years. Three hundred and thirty-one (99%) of 333 had a documented recommendation for follow up of three years or less. Thirty-four percent (113 of 333) had previously undergone colonoscopy; 29% (98 of 333) had previously undergone polypectomy and 54% (180 of 333) were symptomatic at the time of the colonoscopy. Twenty-eight percent (40 of 141) had a family history of colorectal cancer. Pathology at polypectomy included a single polyp and polyps less than 10 mm in 68% and 88% of cases, respectively. Follow up was available in 211 of these cases, 179 (85%) of which had been compliant with follow up colonoscopy. In a univariate analysis, previous colonoscopy (P = 0.035), previous polyps (P = 0.043), asymptomatic status at time of colonoscopy (P = 0.021), polyp size (P = 0.008) and number of polyps (P = 0.010) were significantly associated with patients who were compliant with follow up colonoscopy. A multivariate logistics regression analysis revealed number of polyps (P = 0.036) and polyp size (P = 0.045) to be statistically significantly associated with compliance.
Conclusion: Compliance with follow up colonoscopy after polypectomy is greater than 80%, regardless of age, education, family history, prior colonoscopy, or prior polypectomy. Risk reduction published in the National Polyp Study may likely reflect what can be achieved through the general use of colonoscopy for surveillance.