Download Dentoalveolar Procedures for the Anticoagulated Patient: Literature

BASIC AND PATIENT-ORIENTED RESEARCH
J Oral Maxillofac Surg
65:1454-1460, 2007
Dentoalveolar Procedures for the
Anticoagulated Patient: Literature
Recommendations Versus Current
Practice
Brent B. Ward, DDS, MD,* and Miller H. Smith, DDS†
Purpose: To evaluate the current practice of oral and maxillofacial surgeons in Michigan regarding
perioperative warfarin therapy and dentoalveolar surgery in defined procedure risk groups.
Materials and Methods: Surveys were distributed to all surgeons (n ⫽ 188) registered with the
Michigan Society of Oral and Maxillofacial Surgeons. Low/moderate/high surgery risk groups were
defined based on retrospective data accumulated for procedures on pretransplant liver failure patients.
We requested the surgeon’s maximum tolerated International Normalized Ratio (INR) for each risk
group. In addition, surgeons were asked if their routine practice for each group included continuation
or discontinuation of therapeutic warfarin perioperatively.
Results: A 72.6% response rate was achieved. The average maximum INR cutoff values for the various
risk groups were: low, 2.68; moderate, 2.28; and high, 2.01. Routine discontinuation of warfarin
occurred in these groups 23.6%, 48.8%, and 70.5%, respectively. Using a paired t test, these results
showed statistically significant differences in patient management practices (P ⬍ .001) between the low,
moderate, and high risk groupings.
Conclusion: Lack of uniformity exists regarding warfarin therapy and dentoalveolar surgery. No studies
to date involve significant numbers of moderate/high risk procedures to provide evidence-based support
of safety with maintenance of therapeutic INR. For moderate or high risk procedures, the majority of
surgeons prefer warfarin discontinuation with minimally therapeutic or subtherapeutic levels, a practice
that secondarily increases risk for thromboembolism. Based on these preliminary data, we believe a
prospective trial to elucidate stronger management guidelines for both the moderate and high risk
surgery population is indicated.
© 2007 American Association of Oral and Maxillofacial Surgeons
J Oral Maxillofac Surg 65:1454-1460, 2007
Warfarin sodium was accepted for use as an anticoagulant in 1954.1 Since this time significant controversy in the surgical community has evolved regarding the risks and benefits of continuing versus
cessation of this medication before surgical procedures.2-7 The medical and dental communities have
Received from the Department of Surgery, Section of Oral and
Maxillofacial Surgery, University of Michigan, Ann Arbor, MI.
*Assistant Professor and Program Director.
†Resident.
Address correspondence and reprint requests to Dr Ward: University Hospital, 1500 E Medical Center Dr, Ann Arbor, MI 481090018; e-mail: [email protected]
© 2007 American Association of Oral and Maxillofacial Surgeons
0278-2391/07/6508-0004$32.00/0
doi:10.1016/j.joms.2007.03.003
contributed a wide variety of perioperative management recommendations regarding the maintenance or
modification of warfarin before oral surgical procedures because of a high risk of bleeding.8-18 Serious
thromboembolic events as well as fatalities have been
reported following prolonged discontinuation of warfarin in patients requiring anticoagulation.10,19-21
Therefore, practitioners have sought alternatives to
interruption of warfarin therapy such as bridging therapy, using intravenous heparin, or subcutaneous low
molecular weight heparin to minimize the interval
without anticoagulation.2,3,7,22-24
Multiple case reports and systematic reviews can be
found in the literature supporting the continuation of
warfarin before oral surgical procedures, assuming
that the prothrombin time (in seconds) or the PT ratio
remains within a certain range.20,25-42 The develop-
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WARD AND SMITH
ment of anticoagulant standardization with the international normalized ratio (INR)43-47 and analysis of
outcomes data by the American Heart Association/
American College of Cardiology,48,49 European Society of Cardiology,50-52 and British Committee for Standards in Hematology,53,54 have aided in minimizing
adverse bleeding sequelae for those patients on warfarin. It is clear that before INR standardization, individuals in the past were anticoagulated to a higher
degree, especially in North America where a less
sensitive thromboplastin was used.55 Monitoring regimens56-62 and therapeutic anticoagulation48,49 has
continued to evolve, with resulting improvement in
patient safety.45 Recently, investigations with or without the use of topical procoagulant agents63-68 have
shown the relative safety of continuing warfarin at
therapeutic levels while undertaking certain oral surgical procedures.65,69-87 The definition of the complexity of a procedure varies between patients and
practitioners alike, and only recently has risk stratification for postoperative bleeding in oral surgical procedures been attempted using retrospective data from
pre-transplant liver failure patients.88 It is evident that
most of the current literature supports continuation
of warfarin for minor oral surgical procedures, up to
3 to 5 teeth, while the patient remains in a therapeutic range of anticoagulation. To accurately assess how
risk of procedure changes the surgeon’s treatment of
patients on warfarin, we surveyed the State of Michigan Oral and Maxillofacial Surgeon (OMFS) community to determine their practice habits with anticoagulated patients in various stratified risk groups.
Materials and Methods
SAMPLE
A survey questionnaire was distributed twice to all
188 OMFS registered with the Michigan Society of
OMFS in July 2005. Anonymous prepaid postage return envelopes were provided. The surveys were
numbered for the sole purpose of preventing duplication of data entry. The individual respondents were
never identified with their answers.
SURVEY
A 2-part questionnaire was developed to allow for
simple data acquisition. The questions were as follows:
1) Please indicate the maximal INR you would tolerate for performing procedures in the following groups of patients on warfarin therapy (provided to the nearest 0.5 INR value)
- Low risk (1-5 simple ext)
- Moderate risk (6-10 simple extractions, 1 impacted extraction, 1 quadrant alveolectomy)
FIGURE 1. Maximal INR distribution for low risk dentoalveolar
procedures.
Ward and Smith. Dentoalveolar Surgery in Anticoagulated Patients. J Oral Maxillofac Surg 2007.
- High risk (⬎10 simple extractions, ⬎2 impacted extractions, ⬎2 quadrants alveolectomy,
tori removal)
2) Do you routinely discontinue/continue warfarin
oral anticoagulant therapy before low/moderate/high risk dentoalveolar surgery?
STATISTICAL ANALYSIS
Numerical data were entered onto and analyzed
using SPSS software (SPSS Inc, Chicago, IL). Frequencies for each question were tallied and investigated
for significance using a paired t test (P ⬍ .05).
Results
All 188 surgeon members of the Michigan Society of
OMFS received an initial mailing followed by a duplicate
second mailing 2 weeks later. Fifteen of the surgeons
were excluded because of retirement or incorrect address. One hundred twenty-seven surveys were returned for data collection for an overall response rate of
72.8%; however, 4 surveys were excluded. Three because of incomplete information, and 1 respondent returned both surveys with the same information.
Mean maximal INR values for low, moderate, and
high risk surgical procedures were 2.68, 2.28, and
2.01, respectively. Figures 1 through 3 provide frequency distribution of maximum tolerated INR values
for each risk grouping. All distributions were statistically significant (P ⬍ .001) for the various risk groups.
INR levels below 2.0 were noted 25.2% of the time for
low risk, 50.4% for moderate risk, and 66.7% for high
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DENTOALVEOLAR SURGERY IN ANTICOAGULATED PATIENTS
FIGURE 2. Maximal INR distribution for moderate risk dentoalveolar
procedures.
FIGURE 4. Warfarin usage before low risk dentoalveolar
procedures.
Ward and Smith. Dentoalveolar Surgery in Anticoagulated Patients. J Oral Maxillofac Surg 2007.
Ward and Smith. Dentoalveolar Surgery in Anticoagulated Patients. J Oral Maxillofac Surg 2007.
risk procedures. Routine discontinuation of warfarin
for low, moderate, and high risk procedures was
indicated 23.6%, 48.8%, and 70.5% of the time respectively (Figs 4-6). The practice of discontinuing warfarin was statistically significant for each of the procedure risk groups (P ⬍ .001).
In patients requiring anticoagulation, INR values
are maintained within a therapeutic range set forth by
recommendations provided by various anticoagulation committees. An INR range between 2.0 to 3.0 is
deemed appropriate for patients at risk for arterial and
venous thrombosis.48-54,89 An INR range from 2.5 to
either 3.5 or 4.0 is advocated for mechanical heart
valves by American Heart Association/American College of Cardiology48,49 and European Society of Cardiology/British Committee for Standards in Hematology50-54 recommendations, respectively. An INR
above this range may increase the patient’s risk for a
FIGURE 3. Maximal INR distribution for high risk dentoalveolar
procedures.
FIGURE 5. Warfarin usage before moderate risk dentoalveolar
procedures.
Ward and Smith. Dentoalveolar Surgery in Anticoagulated Patients. J Oral Maxillofac Surg 2007.
Ward and Smith. Dentoalveolar Surgery in Anticoagulated Patients. J Oral Maxillofac Surg 2007.
Discussion
WARD AND SMITH
FIGURE 6. Warfarin usage before high risk dentoalveolar
procedures.
Ward and Smith. Dentoalveolar Surgery in Anticoagulated Patients. J Oral Maxillofac Surg 2007.
spontaneous or surgically induced bleeding episode,90 while an INR below the desired therapeutic
level increases the risk for thromboembolism19,91 and
ischemic cerebrovascular event.21,92
A recent investigation at our institution monitored
surgical complications in pretransplant liver failure
patients. This study showed that postoperative bleeding episodes are dependent on the complexity of the
dentoalveolar procedures performed, and a significant variation exists between low and high risk procedure groups.88 It cannot be assumed that a direct
correlation exists between patients with warfarin anticoagulation and those with liver failure who present
with a variety of coagulopathic concerns. Yet retrospective analysis in the liver failure population led to
the realization that surgeons consistently placed patients into risk categories based on the number of
extractions to be preformed. This evidence caused us
to question the current practice and evidence for
extensive dentoalveolar procedures in the warfarinized patient population. A comprehensive evaluation of the literature was accomplished in an effort to
identify management recommendations based on the
risk categories similar to the liver failure study.
The majority of publications on warfarin and dentoalveloar surgery argue that no increased risk of
postoperative bleeding episodes exists in the surveyed low risk group (1 to 5 simple extractions).20,25,30,32,75,76,79-82,93 A number of reported
studies and review articles state that dentoalveolar
procedures, even within our moderate and high risk
groupings, can be offered without discontinuing warfarin.2,25,81 However, careful evaluation of this litera-
1457
ture shows that the actual procedures were most
appropriately classified as low risk procedures and
very few reports described treatment within the moderate or high risk categories.25,81 For example, Devani
et al81 concluded that dental extractions could be
completed safely without modification of warfarin
therapy in 33 patients. Review of these data showed
that a range of 1 to 9 teeth were extracted in the
patients with an average of 2.1 teeth in the treatment
group and 2.0 teeth in the control group. None of
these patients would qualify for our high risk category, and only a select few would likely qualify for the
moderate risk group. Blinder et al77 evaluated for the
frequency of postoperative bleeding in patients at
various INR levels, concluding that an INR value
within the therapeutic range did not effect postoperative bleeding. These investigators concluded that
dental extractions could be completed in patients
without interruption or diminution of warfarin. Review of their data shows that patients in their therapeutic INR groups received on average 2.06 extractions. Wahl’s2 comprehensive and systematic review
sought to evaluate the risks of thromboembolic stroke
from discontinuation of anticoagulant medication versus the risk of serious life-threatening postoperative
bleeding with therapeutic warfarin. More than 2,014
surgical procedures were reviewed without alteration
of warfarin and concluded that severe postoperative
bleeding not controlled with local measures is rare
and often corresponds with supratherapeutic anticoagulation. Meanwhile, 4 patients experienced fatal
embolic complications following withdrawal of their
medication. It was then acknowledged that “many
authorities state that dental extractions can be performed with minimal risk at or above therapeutic
levels of anticoagulation.”2 Regardless, in this report
an overall average of 2.60 extractions per patient
were performed, well under what would be deemed
high risk dentoalveolar procedures. Interestingly, the
only study evaluating patients undergoing more than
10 extractions was completed by Bailey et al25 in
1983. This report evaluated the continuation of warfarin therapy in 25 patients and compared these data
with non-anticoagulated age-matched controls. The
number of extractions in patients in the treatment
arm ranged from 1 to 20 teeth, with an average of
6.24 teeth.25 The investigators surmised that extractions with therapeutic anticoagulation could be accomplished and any postoperative bleeding could be
easily managed using a specific protocol. It is interesting that 75% of patients (3 out of 4) with 10 or
more extractions were recorded as having late postoperative bleeding scores. One may interpret the literature inappropriately and assume there is adequate
evidence supporting extraction of any number of
teeth in anticoagulated patients; however, in our es-
1458
timation, the paucity of prospective or retrospective
data on patients receiving more than 5 extractions
and/or other invasive dentoalveolar procedures does
not provide adequate information to evaluate the
safety for all daily outpatient treatment.
Our study shows that there exists a significant disparity regarding patient management among OMFS
for various risk-stratified dentoalveolar surgical procedures in warfarin anticoagulated patients. It was surprising to see that more than 23% of surgeons routinely discontinued warfarin for low risk procedures.
The literature supports that the completion of low
risk dentoalveolar procedures is safe if INR values, or
similarly past use of PT-ratios, are in a therapeutic
range.20,25,30,32,75,76,79-82,93 Bleeding episodes are
noted to occur in both experimental and control
groups, and are often adequately controlled using
local measures only.32,36,80,82,94 Rarely, reversal of anticoagulation is warranted, and most often hemorrhage is caused by supratherapeutic levels of warfarin.30,32,95-98 In addition, trials evaluating the
effectiveness of anticoagulant or antifibrinolytic99
products have shown significant benefit in avoiding
postoperative bleeding episodes in patients taking
warfarin.69-74,83,84 Studies have shown that aggressive
local management using local anesthetic with vasoconstrictors, curettage of periodontally compromised
teeth, placing absorbable gelatin or oxidized cellulose
materials, obtaining primary closure with sutures,
and avoidance of unnecessary antibiotics postoperatively can aid in preventing postoperative hemorrhage.77,80,81,100
Based on the current survey results, the majority of
patients are purposely subtherapeutic with respect to
warfarin levels at the time of surgery for moderate
(50%) and high risk (67%) procedures. This practice
may be justifiable given the lack of data in the literature for higher risk procedures. Bridging therapy with
administration of intravenous anticoagulation in a hospital setting101 or intramuscular or subcutaneous anticoagulation in an outpatient setting have been attempted to minimize the time spent at inadequately
anticoagulated levels100,102-106; however, these strategies may not be cost effective,107,108 and have their
own associated risks.109
Overall, a lack of uniformity exists regarding literature recommendations for warfarin and dentoalveolar
surgery and the current practice of OMFS. It is evident
that trends in the literature point to the ability to
continue warfarin in therapeutic ranges for dentoalveolar surgery procedures; however, data are lacking
throughout moderate and higher risk groups, as we
have defined them, and further investigation through
randomized trials is necessary. Based on these data,
we are presently moving forward with a protocol for
a prospective trial that we hope will create guidelines
DENTOALVEOLAR SURGERY IN ANTICOAGULATED PATIENTS
specifically for the moderate and high risk dentoalveolar surgery populations with therapeutic anticoagulation levels.
Acknowledgment
The authors thank Dr Joseph Helman for his guidance, and the
Michigan Society of Oral and Maxillofacial Surgeons for their support.
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