Evaluation of postextraction bleeding incidence to compare patients receiving and not receiving warfarin therapy: a cross-sectional, multicentre, observational study

OBJECTIVES: We investigated incidence and risk factors for postextraction bleeding in patients receiving warfarin and those not receiving anticoagulation therapy. DESIGN: Cross-sectional, multicentre, observational study. SETTING: 26 hospitals where an oral surgeon is available. PARTICIPANTS: Data on 2817 teeth (from 496 patients receiving warfarin, 2321 patients not receiving warfarin; mean age (SD): 62.2 (17.6)) extracted between 1 November 2008 and 31 March 2010, were collected. Warfarin-receiving patients were eligible when prothrombin time–international normalised ratio (PT-INR) measured within 7 days prior to the extraction was less than 3.0. INTERVENTIONS: Simple dental extraction was performed, and incidence of postextraction bleeding and comorbidities were recorded. PRIMARY AND SECONDARY OUTCOME MEASURES: Postextraction bleeding not controlled by basic haemostasis procedure was clinically significant. RESULTS: Bleeding events were reported for 35 (7.1%) and 49 (2.1%) teeth, of which 18 (3.6%) and 9 (0.4%) teeth were considered clinically significant, in warfarin and non-warfarin groups, respectively, the difference between which was 3.24% (CI 1.58% to 4.90%). The incidence rates by patients were 2.77% and 0.39%, in warfarin and non-warfarin groups, respectively (incidence difference 2.38%, CI 0.65% to 4/10%). Univariate analyses showed that age (OR 0.197, p=0.001), PT-INR (OR 3.635, p=0.003), mandibular foramen conduction anaesthesia (OR 4.854, p=0.050) and formation of abnormal granulation tissue in extraction socket (OR 2.900, p=0.031) significantly correlate with bleeding incidence. Multivariate analysis revealed that age (OR 0.126, p=0.001), antiplatelet drugs (OR 0.100, p=0.049), PT-INR (OR 7.797, p=0.001) and history of acute inflammation at extraction site (OR 3.722, p=0.037) were significant risk factors for postextraction bleeding. CONCLUSIONS: Our results suggest that there is slight but significant increase in the incidences of postextraction bleeding in patients receiving warfarin. Although absolute incidence was low in both groups, the bleeding risk is not negligible.