Purpose: Guidelines for colonoscopic surveillance after the removal of colorectal polyps already exist in the United Kingdom and United States. However, there is a continuing need to build up an evidence base on the likely effect of different follow-up policies for specific current findings. This article reports on the colonoscopic surveillance of a cohort of patients in Taiwan. The risk of various outcomes at the second examination is assessed according to findings at the first examination and the interval between examinations.
Patients and methods: Data from baseline and follow-up examinations for 2,287 individuals attending the National Taiwan University Hospital were collected retrospectively. Multivariate logistic regression was used to identify risk factors for the following 4 outcomes: any positive findings; multiple (> or =3) polyps; large (> or =10 mm) polyp(s); or villous adenoma(s) or cancer. The effect of the interval between examinations was assessed in all models.
Results: Older age was an independent risk factor for all outcomes. The number of baseline polyps was a significant risk factor for both positive results and multiple polyps, more severe baseline histology was a risk factor for large polyps and villous adenomas/cancer, and larger baseline polyps were a risk factor for large polyps at follow-up. Interval time was only an independent risk factor for villous adenomas/cancer, which tended to be found at shorter follow-up times. The total number of abnormalities found at follow-up was significantly related to the number of follow-up examinations but not to the total follow-up time.
Conclusions: Results suggest that, with the possible exception of subjects with villous adenomas at baseline, most reexaminations can safely be delayed for > or =5 years. In the majority of cases staff at the hospital were correctly identifying those subjects at particularly high risk and assigning shorter follow-up intervals accordingly. Models indicate that many of the findings seen at follow-up were due to missed baseline findings.