NEW YORK, NY—Potentially practice-changing research from Nigel Sharrock, MB, ChB, and colleagues at New York’s Hospital for Special Surgery suggests that surgeons should stop routinely prescribing potent anticoagulants to stave off pulmonary embolism following joint arthroplasty. The study, which shows that these blood thinners may actually lead to more deaths, is published in Clinical Orthopaedics and Related Research.¹

"We believe the American College of Chest Physicians should reconsider their guidelines to reflect that fact that pulmonary embolism occurs despite the use of potent anticoagulants and [that they] may in fact expose patients to increased mortality after surgery," conclude the researchers led by Dr. Sharrock, an anesthesiologist.

During the last 2 decades, deaths from pulmonary embolism have fallen significantly due to a combination of advancements in anesthesia, better surgical techniques, and pre- and post-surgery care, as well as a better understanding of how thrombosis develops as a result of surgery.

"The current low incidence of symptomatic and fatal pulmonary embolism raises the question of whether potent anticoagulation is warranted because these agents have potential side effects [caused by] bleeding," Dr. Sharrock said.

Anticoagulants may do more harm than good

The researchers reviewed 20 studies comprising >28,000 joint arthroplasty patients among 3 groups. Group A received low molecular weight heparin, ximelagatran, fondaparinux, or rivaroxaban; group B received local spinal or epidural anesthesia or pneumatic compression; and group C warfarin.

The researchers found that patients in groups A and C who took potent anticoagulants were more than twice as likely to have died of a fatal pulmonary embolism. The lowest number of deaths occurred in group B counterparts who received local spinal or epidural anesthesia, pneumatic compression, and aspirin. Moreover, there was no difference in the number of deaths between groups A and C, the study showed.

Patients in group A were also at 60% to 70% greater risk of nonfatal pulmonary embolism than those in group B, suggesting that pulmonary embolism occurs despite the use of powerful anticoagulants.

Consider aspirin in some knee arthroplasty patients

The new findings coincide with research presented at the recent annual meeting of the American Academy of Orthopaedic Surgeons.² In that report, Kevin J. Bozic, MD, MBA, an orthopaedic surgeon at the University of California, San Francisco department of orthopaedic surgery, found that taking aspirin to prevent blood clots after knee surgery may be a safe and effective alternative to other blood-thinning drugs.

 “Given the modern, less invasive techniques that orthopaedic surgeons are using now for total knee replacement, aspirin should be reconsidered a viable alternative to recommended therapies,” Dr. Bozic said. What's more, today's knee replacement patients are also younger and less sedentary than in the past, putting them at a lower risk for blood clots after surgery.

Researchers compared data from >93,840 patients who underwent knee replacement surgery at ~300 hospitals between October 2003 and September 2005. Patients who received aspirin had fewer risk factors for blood clots prior to surgery, lower risk of blood clots compared to patients on warfarin, similar odds of developing a blood clot as patients receiving injectable therapies, and no difference in bleeding risks or mortality.

“Aspirin is a simple, inexpensive and commonly used drug with few side effects, so it’s a very attractive alternative,” Dr. Bozic said. More research is needed to determine which patient characteristics and treatment factors are best suited for aspirin use to prevent blood clots in knee replacement patients.

Translating research into practice

Dr. Sharrock emphasized that his group did not define the ideal thromboprophylaxis regimen, but showed that postoperative pulmonary embolism occurs despite the use of anticoagulants and that these drugs may lead to higher mortality.

“It is possible lower doses of group A anticoagulants, combined with regional anesthesia and pneumatic compression, could be efficacious. Nevertheless, any potential benefit must be balanced against the risk of bleeding,” he said.

Current recommendations from the Chest Physicians consensus statement advocate low molecular weight heparin or warfarin for prophylaxis after total hip replacement and total knee replacement. But Dr. Sharrock believes that should change.

“These recommendations often result in physicians feeling compelled to prescribe these anticoagulants to avoid potential litigation. The increased risk of bleeding complications has encouraged several experienced surgeons who perform joint arthroplasty to emphasize caution in the use of these anticoagulants.” Dr Sharrock said. He urges the Chest Physicians to reconsider their guidelines based on the findings.

References

1. Sharrock NE, Della Valle AG, Go G, et al. Potent anticoagulants are associated with higher all-cause mortality rate after hip and knee arthroplasty. Clin Orthop Relat Res. 2008; 466:714-721.
2. Bozic KJ, Auerbach A, Maselli J, et al. Is there a role for aspirin in venous thromboembolism prophylaxis following total knee replacement? Presented at: AAOS annual meeting; March 7, 2008; San Francisco, Calif. Presentation 073.