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Anticoagulants May Increase Mortality After Hip and Knee Surgery
To our science people: Is this potentially relevant to Atryn?

Anticoagulants May Increase Mortality After Hip and Knee Surgery

Reuters Health Information 2008. © 2008 Reuters Ltd.
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NEW YORK (Reuters Health) Apr 02 - A review of studies looking at anticoagulant prophylaxis after hip and knee arthroplasty reveals that not only do these agents fail to completely prevent pulmonary embolism (PE), their use may actually increase all-cause mortality.

The results, which appear in the March issue of Clinical Orthopaedics and Related Research, show that the risk was most pronounced with so-called potent anticoagulants, such as low-molecular weight heparin, ximelagatran, fondaparinux, and rivaroxaban. Warfarin, a slow-acting oral anticoagulant, raised the risk to a lesser extent.

Lead investigator Dr. Nigel E. Sharrock and colleagues argue that the findings call for a revision of American College of Chest Physician (ACCP) guidelines, which advocate the use of low-molecular-weight heparin or warfarin in this setting.

Anticoagulation is primarily prescribed after hip and knee replacement to prevent fatal PE, note the research team from the Hospital for Special Surgery in New York. In the 1960s, fatal PE rates of up to 2.2% were reported, but now, due to advances in anesthesia, surgery, and perioperative care, rates do not exceed 0.2%.

The current low rate of PE, the authors state, raises the question of whether the antithrombotic benefits of potent anticoagulation outweigh the potentially serious bleeding risks. No studies to date have confirmed that anticoagulation after hip and knee arthroplasty reduces all-cause mortality, they point out.

To clarify the risks and benefits of anticoagulant use in this setting, Dr. Sharrock's team reviewed data from 20 studies, published between 1998 and 2007, that involved over 28,000 patients. Included were 15,839 subjects treated with a potent anticoagulant, 7193 who received regional anesthesia, pneumatic compression and aspirin, and 5006 given warfarin.

Patients who received a potent anticoagulant or warfarin had all-cause mortality rates of 0.41% and 0.40%, respectively. By contrast, patients not treated with these agents had a rate of just 0.19%.

Similar results were seen regarding nonfatal PE. Patients treated with potent anticoagulants or warfarin had rates of 0.60% and 0.52%, respectively, while patients not treated with anticoagulants had a rate of 0.35%.

The ACCP recommendations "often result in physicians feeling compelled to prescribe these anticoagulants to avoid potential litigation," the investigators comment. "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 and colleagues conclude: "We believe that ACCP should reconsider their guidelines to reflect the fact that PE occurs despite the use of potent anticoagulants and may, in fact, expose patients to increased mortality after surgery."

Clin Orthop Relat Res 2008;466:714-721.

Source: http://www.medscape.com/viewarticle/572419_print