EFFECT OF DIMINUTIVE POLYPS WITH HGD ON SURVEILLANCE COLONOSCOPY

Aims The colonoscopy surveillance guideline AGA 2012 and ESGE 2013, set the surveillance schedule based on the characteristics of polyp. Polyp with high grade dysplasia (HGD) requires three years of follow-up regardless of size. It is unclear whether diminutive polyps (less than 5 mm) with HGD have more risk than the low risk group. Therefore, in this study, the effect of diminutive with HGD on the occurrence of Advanced adenoma was analyzed.

Methods From Jan 2015 to Dec 2017, all patients who underwent index and surveillance colonoscopy were retrospectively screened, and after the exception of 298 cases, 1210 patients were included. Through logistic analysis, Patients were grouped into diminutive HGD group, low risk group (patients with no polyp, 1-2 low grade dysplasia (LGD) patients), and high risk group (HGD >5mm, 3 or more adenoma) according to the index colonoscopy results. Advanced adenoma was defined as follow; adenoma with ⩾1 cm in size, tubule-villous or villous adenoma, high grade dysplasia.

Results The mean follow-up period was 22.47 (95% CI, 21.65-23.33 month). 610 patients had LGD (50.45%) and 152 patients (12.5%) had HGD. Among them, 61 patients (5.0%) had diminutive polyp with HGD. The risk of developing advanced adenoma in the surveillance colonoscopy was analyzed. Compared with the low risk group, diminutive HGD group didn`t showed significant risk (OR = 1.634 (95% CI, 0.843-3.168), p = 0.142), but the high risk group showed a significant risk (OR = 1.428 (1.027-1.984), p = 0.034).

Conclusions Diminutive HGD does not increase the risk of developing advanced adenoma compared to the low risk group.