Francesco Chiappelli Ph.D; Michael Montgomery DDS; Juan F. Yepes DDS, MD, MPH, FDS RC
Continuing the regular dose of warfarin therapy during minor dental surgery does not appear to increase the risk of bleeding compared to discontinuing or reducing the dose.
What is the difference in bleeding after minor dental surgery between patients who continue warfarin therapy and patients whose dose was reduced or interrupted?
The authors searched 3 electronic databases for articles published through June 2008. In addition, they manually searched bibliographies of published articles and contacted content experts. The selection criteria included randomized controlled trials that assessed either thromboembolism or postoperative bleeding between subjects who continued warfarin therapy and those who either reduced or discontinued their warfarin dose. NonEnglish language studies were excluded. Two independent observers selected studies and their agreement was determined by Kappa scores. Discrepancies were resolved by consensus and a meta-analysis was performed on the accepted studies.
The authors identified a total of 207 studies, 127 of which were excluded after they screened study titles and abstracts using predefined inclusion and exclusion criteria. The remaining 80 studies were retrieved for detailed evaluation, with 5 studies included in the systematic review (553 patients). Four of the 5 studies were rated as of low quality and only 4 studies were included in the comparisons of 2 outcomes. Most of the dental surgery procedures were simple, single tooth extractions. Bleeding was re-categorized as either major, clinically significant nonmajor and minor. Thromboembolic events were also recategorized, but thromboembolic events and major bleeding were dropped as outcomes because of low subject numbers and insufficient study durations. Clinically significant nonmajor bleeding occurred in 15 of 275 (5.5%) patients who continued their regular dose of warfarin and in 25 of 278 (9%) patients who discontinued or altered their dose of warfarin before elective dental surgery. Minor bleeding occurred in 41 of 210 (19.5%) patients who continued their regular dose of warfarin and in 40 of 212 (18.9%) patients who discontinued or altered their dose of warfarin before elective dental surgery. These differences between the two patient populations were not statistically significant in both bleeding categories.
Continuing the regular dose of warfarin does not seem to confer an increased probability of bleeding compared with discontinuing or reducing the warfarin dose for patients undergoing minor dental surgery.
Source of Funding:
Importance and Context:
Warfarin therapy is used to reduce the risk of stroke and recurrent venous thromboembolism in more than 4 million patients throughout North America. Managing patients who require both anticoagulant therapy and surgery is a challenge. Practitioners must balance the increased probability of thromboembolism associated with a temporary interruption of warfarin against the increased probability of bleeding if anticoagulant therapy is continued. This systematic review aimed to compare the risk of bleeding following minor dental surgery, in patients who continued warfarin therapy with that of patients whose dosage was reduced or interrupted.
Strengths and Weaknesses of the Systematic Review:
The authors used recommended methods (QUOROM) to identify appropriate studies. The data extraction was performed independently and multiple evaluators assessed the quality of the studies. Evaluator agreement was acceptable and appropriate measures were used to resolve disagreements. However, the authors did not control for language bias and the resultant sample size was small and of questionable quality. As a result, extrapolation of the findings to the general population should be made with caution.
Strengths and Weaknesses of the Evidence:
The strength of the review is undermined by the small number of appropriate studies, the poor quality of these studies, and the heterogeneity between them. Uncontrolled variables within and between studies included subject randomization, subject and operator blinding, subject withdrawals, the degree of subject anticoagulation, the use of antifibrinolytic agents, the use of co-interventions, subject co-morbidities and the types of dental surgery performed. In addition, limiting the comparison to bleeding impaired the clinical relevance of the findings. The evaluation of additional factors such as other morbidities, total treatment costs and patient time investment, would have improved the clinical relevance of this systematic review.
Implications for Dental Practice:
In patients undergoing minor dental surgeries ((mainly simple single tooth extractions), continuing the regular dose of warfarin does not seem to increase the risk of bleeding when compared with discontinuing or reducing the warfarin dose. However, because of weaknesses in the evidence, practitioners should use caution in the clinical application of these findings.