Louis H.S. Lau 1,2, Cosmos L.T. Guo 1,2, K.K. Lee 2, Clive S.T. Chan 2, Joyce W.Y. Mak 1,2, Sunny H. Wong 1,2,3, Terry C.F. Yip 1,2,4, Grace L.H. Wong 1,2,4, Francis K.L. Chan 1,2, Raymond S.Y. Tang 1,2

1Department of Medicine and Therapeutics, The Chinese University of Hong Kong, Hong Kong, 2Institute of Digestive Diseases, The Chinese University of Hong Kong, Hong Kong, 3State Key Laboratory of Digestive Disease, Li Ka Shing Institute of Health Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong, 4Medical Data Analytic Centre (MDAC), Department of Medicine and Therapeutics, The Chinese University of Hong Kong, Hong Kong

Background/Aims: Warfarin and direct oral anticoagulants (DOAC) are significant risk factors of post-polypectomy bleeding (PPB) following polypectomy in colonoscopy. Efficacy of prophylactic clipping to reduce PPB is inconsistent, except in proximal and large colonic lesions. Dedicated studies to examine the benefit of prophylactic clipping in high-risk patients on oral anticoagulants remain limited.

Methods: We performed a propensity-score weighted retrospective cohort study in Hong Kong from 2012 to 2020. Patients who received an oral anticoagulant and underwent colonoscopic polypectomy were identified. Data on baseline demographics, medications (anticoagulant, antiplatelet and heparin bridging) and endoscopic factors (number, location, size, morphology, histopathology, polypectomy mode and prophylactic clipping) were captured. Propensity-score models with inverse probability of treatment weighting were developed between prophylactic clipping and no clipping groups. Unbalanced variables were included in doubly robust model with multivariate logistic regression analysis. The primary outcome was clinically significant delayed PPB, defined as repeat colonoscopy requiring hemostasis within 30 days.

Results: Total 547 patients were included. Prophylactic clipping was not associated with an overall reduced risk of PPB (odds ratio (OR) 1.00, 95%CI 0.59-1.74, p= 0.988). Mean number of polyps (OR 1.10, 95%CI 1.02-1.18, p= 0.009), pedunculated morphology (OR 1.89, 95%CI 1.01-3.49, p= 0.044) and polypectomy mode with electrocautery (OR 3.94, 95%CI 1.71-11.06, p= 0.003) were significant risk factors of PPB. In subgroup analysis, prophylactic clipping was associated with a lower PPB risk in DOAC users (OR 0.26, 95%CI 0.09-0.67, p= 0.008).

Conclusion: Prophylactic clipping application was not associated with an overall reduced risk of PPB in patients on oral anticoagulants.

Keywords: anticoagulant, polypectomy, gastrointestinal bleeding, prophylactic clipping