Development and Validation of Oral Bleeding Risk Scoring System (OBRS) for Predicting Post-tooth-extraction Bleeding in Patients Undergoing Treatment with Warfarin: A Single Centre Study

Introduction: This study aimed to develop an oral bleeding risk scoring system (OBRS) for predicting the post-tooth-extraction bleeding risk in patients medicated with warfarin.Materials and Methods: We included a derivation cohort of 211 consecutive inpatients from April 1, 2013 to March 31, 2015 and a validation cohort of 63 consecutive inpatients from April 1, 2015 to March 31, 2016 who underwent tooth extraction at Tokyo Women's Medical University hospital. Post-tooth-extraction bleeding was observed in 29 (13.7%) cases in the derivation cohort. Using multivariate logistic analysis, three predictors (international normalized ratio of prothrombin time: PT-INR, drugs, incision) were selected for the final model.Results: OBRS was derived as follows: PT-INRÁE+drugs+incision. Receiver operating characteristic curves provided area under the curve of 0.77 (95%CI, 0.67 to 0.85) for OBRS, 0.61 (95% CI, 0.50 to 0.71) for HAS-BLED score, and 0.69 (95% CI, 0.56 to 0.79) for PT-INR. The high-risk cut-off OBRS value was 5.08 points. Post-tooth-extraction bleeding was observed in 9 (14.2%) cases in the validation cohort. Sensitivity and specificity were 100% and 90.7%, respectively. The OBRS showed excellent performance with respect to predictor score.Conculusions: The proposed OBRS showed good performance for predicting post-tooth extraction bleeding in patients undergoing warfarin treatment.