Risk Factors and Prediction of Bleeding after Endoscopic Submucosal Dissection in Patients on Antithrombotic Therapy: The SAMURAI Model

Background: Bleeding after gastric endoscopic submucosal dissection (ESD) remains problematic, especially in patients receiving antithrombotic therapy. Thus, our study aimed to identify the risk factors and to create a prediction model for post-ESD bleeding in patients receiving antithrombotic therapy. Methods: Patients receiving antithrombotic therapy who underwent gastric ESD at Osaka Medical College Hospital and at 18 referral hospitals all over Japan were enrolled. Risks of post-ESD bleeding were calculated using multivariable logistic regression. The dataset was randomly divided into derivation cohort (70%) and validation cohort (30%). We created a prediction model using derivation cohort. The accuracy of the model was evaluated using the validation cohort. We compared this model with an existing scoring method, using NRI (net reclassification improvement) and IDI (integrated discrimination improvement). Findings: The study enrolled 1207 patients. Post-ESD bleeding occurred in 142 (11·8%) cases. Multivariable analysis yielded an odds ratio of 1·73 for aspirin, 4·18 for P2Y12 receptor antagonist, 1·42 for cilostazol, 0·80 for other antiplatelet agents, 4·12 for warfarin, 3·76 for dabigatran, 5·14 for apixaban, 6·74 for edoxaban, 4·22 for rivaroxaban, and 1·56 for heparin bridging. The prediction model (SAMURAI model) was created for patients receiving antithrombotic therapy, and it had a good predictive ability with a C-statistic of 0·74. The model had a significantly better predictive ability than a previously reported model (NRI=0·41, 0·15–0·66, p=0·002, IDI=0·05, 0·02–0·08, p=0·002). Interpretation: In this study, the risk of post-ESD bleeding for each antithrombotic agent was evaluated. Use of the SAMURAI model will allow the proactive management of post-ESD bleeding risk during antithrombotic therapy. Funding: 2nd Department of Internal Medicine, Osaka Medical College, Japan Declaration of Interest: The authors declare that there are no conflicts of interest associated with this manuscript. Ethical Approval: This study was conducted according to the guidelines of the Declaration of Helsinki. The study was approved by the Ethics Committee of Osaka Medical College (trial number: 693) and by the institutional review board of each participating institution before the recruitment of patients. Informed consent for this study was obtained in the form of opt-out on the website of each participating hospital. All authors had access to the study data and reviewed and approved the final manuscript.