Study: Risk of post-op bleeding minimal in warfarin users

2011 05 09 15 19 48 6 Blood Cells 70

A retrospective study investigating the frequency of postoperative bleeding complications following invasive dental procedures on patients using warfarin has found few episodes (Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology, October 2012, Vol. 114:4, pp. 464-468).

Researchers at the Department of Oral Medicine at Carolinas Medical Center noted only a 4.8% frequency of bleeding, or five of 122 patients observed.

"We found in most cases that if the patient is on therapeutic levels of warfarin, you can proceed," one of the study's lead authors, Joel Napenas, DDS, director of general practice residency at Carolinas Medical Center, told "You'll have a very low incidence of postoperative bleeding complication, so even if you were to run across some, they usually can be controlled by local measures at the dentist."

The need to modify or discontinue a patient's anticoagulation medicine prior to an invasive dental procedure is "controversial," he and his co-authors noted. However, Dr. Napenas was clear about his opinion of the practice.

“It's relatively safe to go ahead and do procedures.”
— Joel Napenas, DDS

"Asking patients to discontinue these blood-thinning medications before any dental work is not a prudent thing to do," he stated. "The implications of discontinuing these prescriptions are greater than any postoperative bleeding complications that we get."

While patients who are only on warfarin are at minimal risk, the researchers considered other variables in their study and noted an area of greater concern.

"What we found was that individuals who were on several blood thinners, not just warfarin, were the ones who were at higher risk," Dr. Napenas said.

International normalized ratio

He and his colleagues used the CoaguChek system (Roche Diagnostics) to ascertain each patient's international normalized ratio (INR), a commonly used metric when monitoring oral anticoagulant therapy and for warfarin dosage planning. Typical INR for those not on warfarin is 1; it ranges from 2 to 4 for those on the drug, with some variation based on the patient's need for it, according to the study authors.

"Currently, most guidelines indicate that patients with an INR less than 3.5 can undergo minor oral surgery without any adjustment in anticoagulation," they wrote. Some put the safety limit at 4, although it was set at 3.5 for the study.

That number has increased over time: A 2008 Carolinas Medical Center anticoagulant study found that on the day of an extraction, an INR of 2.5 or less is appropriate.

"Based on the current literature and findings from our study, we can report that simple extractions with adequate local hemostatic measures and dental cleanings (ultrasonic scaling and prophylaxis) could be completed in patients with INR levels of up to 4.0 and without other coagulopathies associated with medication or disease," Dr. Napenas and his colleagues wrote in the current study.

Patient demographics and clinical information were noted, particularly as they pertained to additional anticoagulants being taken -- specifically aspirin, clopidogrel, and nonsteroidal anti-inflammatory medications. The researchers also collected information about the type of dental procedure performed, hemostatic agents used during those procedures, the use of pre- and postoperative blood products, and the nature and duration of postoperative bleeding.

"We wanted to see exactly what the outcomes were for those patients," Dr. Napenas said. "In other words, what is their INR when we do the screening, and then what is the occurrence of any postoperative bleeding complications."

‘Relatively safe'

Their study included 122 patients, half of whom were male, who had an average age of 57. Of the patient group, 35 were on concomitant prescriptions that could potentiate bleeding, and 28 were taking other medications in addition to warfarin: 16 were taking aspirin, four were on enoxaparin, two were on clopidogrel, and six regularly took nonsteroidal analgesic medications.

Seven patients included in the study were not taking warfarin but were on multiple antithrombotic medications. And 10 had medical histories that could affect their risk for bleeding, such as kidney transplant candidates.

From June 2004 to June 2010, the patients had a total of 240 dental appointments, where the researchers recorded an average INR value of 2.4 ± 1.2 with a range of 0.8 to above 8 and a median of 2.2. In that time, 31 operators placed two implants and performed 248 extractions. Multiple extractions, with an average of 4.3 ± 3.5 teeth in a range of 2 to 20 removed per appointment, were performed during 41 appointments.

The researchers found only five episodes (2%) of persistent bleeding when all 240 appointments were included. However, that percentage increased to 4.8% if recalculated to only consider surgical procedures. Among those patients, the average INR was 2 ± 0.8.

The postoperative bleeding complication rate was significantly higher (p < 0.05) in appointments where patients were taking concomitant medications (in addition to warfarin; 17%, 4 of 27), compared with those where patients were on warfarin only (1%, 1 of 78), the researchers noted. The odds ratio for bleeding in the former patient set was 13.31.

"Five episodes among 122 patients is a very low frequency," Dr. Napenas said. All of those patients had an INR reading of 3.3 or lower, well within the recommended range for proceeding with most invasive dental procedures, the researchers noted. In other appointments, eight patients with INR values higher than 3.3 successfully had extractions (n = 7) or implants placed (n = 1) without postoperative bleeding. And four of those five who did experience it were concomitantly using medications.

"I think it's relatively safe to go ahead and do procedures as long as the INR is in their therapeutic levels," Dr. Napenas said. "Not everybody necessarily has the luxury of getting an INR right on the spot like we are able to, so if there is any question as to whether or not they can do a procedure, dentists should try to get that information about the patient through the their medical doctor."

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