The Concordance between Laboratory and POCT INR and the Value of Bedside Measurement of INR in Patients on Warfarin Undergoing Dental Procedures: A Prospective Cohort Study

Abstract

Introduction: Patients on anticoagulation particularly warfarin suffers when they have a dental problem that requires intervention. Most of dentists worry and refuse to perform procedures on patients on warfarin because of the risk of bleeding and request the availability of international normalized ratio (INR) results before procedure which can delay the procedure and add another burden on the patient particularly who live away from the treating center. Objective: To evaluate the efficacy and the value of using point of care testing (POCT) (INR) in patients on warfarin undergoing dental procedures. We also had analyzed the frequency and severity of dental bleeding in patients on warfarin therapy and the concordance between Laboratory based INR and POCT INR. This is the first interim analysis on ongoing prospective study. Methods: A cohort study of 30 patients on chronic use of anticoagulation therapy with warfarin for different clinical indications who planned to undergo dental procedures at a teaching hospital in Saudi Arabia. The patients' demographic and clinical characteristics, type and severity of bleeding, and INR measured by both HemoChrone (POCT) and prothrombin time (PT) were performed at same time. Descriptive statistics, paired samples statistics, correlations, and analysis of variance (ANOVA) were performed. Results: The sample consisted of 60% females, with a mean age of 49.9 (SD 13.3) years. The most common indications for warfarin therapy were mechanical aortic valve replacement (56.7%), atrial fibrillation (13.3%), and atrial flutter (16.7%). Before the procedure, the mean Laboratory INR was 2.6 (SD 0.6) and the mean HemoChrone POCT INR was 2.8 (SD 0.8). There was a significant positive correlation between the two methods (r = 0.81, p < 0.001). There was no significant difference in the INR and type of bleeding, dentist performed the procedure, or dose of warfarin. There was no correlation between the Bleeding severity or type and the INR level in patients undergoing different dental procedures. Even among those with HemoChrone POCT INR > 3, which is considered high and increases the risk of bleeding, there was no significant correlation with bleeding. Conclusion: These results imply that warfarin therapy can be safely continued for most dental procedures without increasing the risk of bleeding regardless of the INR results. The HemoChrone POCT INR is a dependable and practical method to monitor the effect of warfarin in dental settings which can reassure the dentists before procedure. Figure 1: The concordance between Laboratory and POCT INR