An interesting article titled “Postoperative Bleeding Following Dental Extractions in Patients Anticoagulated With Warfarin” written by Anthony Febbo and et al. appears in the 2016 Journal or Oral and Maxilofacial Surgery (vol. 74, pp. 1518-1523). The article sought to explore the risk of bleeding in patients on warfarin after dental extraction.
Warfarin is the most common anticoagulant used in Australia which can be used to prevent life-threatening thromboembolic events, such as stroke and deep vein thrombosis from occuring in patients at risk. Varying viewing points exisist as how to best handle these patients when a tooth or teeth need to be extracted. Some options include stopping the anticoagulant before extraction or continuing to use it while local hemostatic techniques are used. However ceasing the anticoagulant could be deadly so it is not generally used. The therapeutic effect of warfarin is measured as prothrombin time and communicated as the international normalized ratio (INR) with most patients between a value of 2 and 3 for INR.
Prior studies have shown a rate of bleeding after dental extraction of approximately 2 to 8% for patients on warfarin but this includes specialistic centers with highly trained dentists or oral surgeons. The authors sought to find the risk of bleeding of dental extractions performed by junior practitioners for patients on warfarin. Patients who were treated at the Adelaide Dental Hospital in Australia were included in the study. A total of 439 patients were included on warfarin and had at least 1 dental extraction and were compared to a control group of 439 patients who had at least 1 dental extraction but not on any anticoagulant. For those patients on warfarin with an INR of 2.2 to 4.0, further management after an extractions was performed. This included irrigation of the socket with a 4.8% solution of tranexamic acid, placement of an oxidized cellulose absorbable hemostatic agent within the socket, and closure by suturing. Then, patients were required to bite on gauze soaked in tranexamic acid for 30 minutes.
Of the 439 patients taking warfarin, 9 patients (2.1%) returned with postoperative bleeding 0 to 10 days postoperatively. There were no cases of bleeding after extraction in the control group of 439 patients not taking warfarin. There was also no bleeding in patients with an INR less than 2.2. Furthermore, there was no difference found in the rate of bleeding between patients with an INR less than 2.2 and control patients not taking an anticoagulant. Logistic analysis was performed. For every increase in INR by 1, the odds of bleeding increased by approximately 13. For every extra extraction, the odds of bleeding increased by 1.28. The posterior mean of bleeding was 1% for an INR lower than 2.2, 2.3% for an INR of 2.2 to 3, and 8.4% for an INR higher than 3.
The authors state
“For those with an INR of 2 to 3, there is a 95% probability that the risk of bleeding is approximately 1 in 100 to 1 in 25. For those with an INR higher than 3, there is a 95% probability that the risk of bleeding is approximately 1 in 30 to 1 in 7.”
It should also be noted that patients with an INR higher than 4 were excluded from this study as they have a much greater bleeding risk.