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A balanced approach to risk/benefits of thromboembolic prophylaxis is needed
For 20 years, DVT and PE have been the most common reason TJR patients are readmitted.
It will take a balance of proven screening and diagnostic techniques coupled with proactive, patient-appropriate prophylaxis measures to reduce venous thromboembolic rates associated with hip and knee arthroplasty surgery, according to William J. Maloney, MD.
Among most major orthopedic cases done without prophylaxis, 40% to 60% will have a DVT (deep venous thrombosis), he said.
Waiting until the patient has symptoms is ineffective and, in some cases, too late to intervene.
“Most people who have a PE (pulmonary embolism) never have symptoms of a DVT. In order to prevent fatal PE, you have to look at preventing DVT,” Maloney said in a presentation at Orthopedics Today Hawaii 2008. He recommended a balanced approach to DVT prophylaxis as best for attaining the optimal combination of minimized bleeding as well as clotting in patients undergoing hip and knee replacement.
Consider risk factors
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Image: Trace R, Orthopedics Today |
Maloney discussed risk factors that might affect that balance and could play a role in who clots and who does not: Age, male gender, genetic factors, a history of prior clots and possibly obesity, varicose veins and surgical time.
But more research needs to be done into these areas to clarify how each of them impacts results with the different prophylactic approaches. In addition more research needs to be performed on the genetics of clotting, he told Orthopedics Today.
Using appropriate prophylaxis measures, mostly those ranked 1A in the newest chest physicians’ guidelines, can effectively reduce the number of venous thromboembolic events after total hip and knee arthroplasty surgery and may save lives.
New protocols
“It is also important to remember that much of the clinical research that goes into determining the effectiveness of a given prophylactic regimen was done in the past when postoperative protocols were much different,” Maloney said. Patients often stayed in bed for several days and were in the hospital for more than a week. This is no longer the case. Patients often get out of bed on the day of surgery and go home in a couple of days.
“In light of the dramatically different rehabilitation protocols after total joint replacement emphasizing early mobilization, much of the clinical research on DVT prophylaxis warrants repeating,” Maloney said. “With early mobilization and more rapid return to activity, the risk-benefit profile for chemoprophylaxis may be substantially different.”
Despite that, DVT and PE remain a problem after joint replacement surgery. “If you look at the most common reason why patients come back to the hospital after hip and knee replacement, it is not infection. It is not dislocation or a periprosthetic fracture. It is a DVT or PE and that has not changed over the past 20 years. The argument to reduce DVT, I think is quite strong. In order to reduce bleeding complications, thrombosis and readmissions, we need to have effective but also safe prophylaxis and that’s where I think a balanced approach needs to be emphasized,” Maloney said.
Many DVT prophylaxis measures are effective in reducing thrombosis and “in the absence of prophylaxis, the DVT rate is obviously high,” Maloney said.
The American College of Chest Physicians guidelines report aspirin is not recommended for total joint arthroplasty surgery. Pneumatic compression is an inferior prophylactic measure at least for hip replacement patients and mechanical methods are not recommended as primary prophylaxis based on research findings.
Surgeons should also disregard low-dose unfractionated heparin, he added. “In Contrast, adjusted-dose unfractionated heparin is effective, but monitoring of the aPTT (activated partial thromboplastin time) is quite cumbersome,” Maloney said.
Warfarin sodium
Maloney explained warfarin sodium (Coumadin, Bristol-Meyers Squibb) is effective with a 2.5 targeted International Normalized Ratio (INR); however his group shoots for a 2.0 targeted INR. They give the initial dose the night before surgery and the second the night of surgery.
“In our experience, this approach is equivalent to low molecular weight heparin (LMWH) in terms of prophylaxis with low risk of bleeding,” he said.
In another study of more than 3,000 patients, warfarin sodium and LMWH prophylaxis resulted in a low rate of in-hospital symptomatic DVTs; however the post-discharge DVT prevalence was higher with LMWH.
Overall, patients who receive warfarin as primary prophylaxis may have a slighter higher DVT rate; however LMWH and fondaparinux sodium (Arixtra, GlaxoSmithKline) may produce a little more bleeding. Selecting between the various regimens available is the physician’s choice based balancing risk vs. benefit taking into account patient risk factors,” he said.
Maloney discussed VTE prevention by type of procedure. Again, balancing risks vs. benefits is important.
“I think bleeding in the hip is something we want to avoid, but bleeding in the knee can be an absolute disaster,” he said. Major hematoma formation can increase the risk of infection and compromise long term outcome.
For more information:
- William J. Maloney, MD, is the Elsback-Richards professor and chair, department of orthopedic surgery, Stanford University School of Medicine. He can be reached a 300 Pasteur Drive, Edwards R109, Stanford, CA 94305; 650-723-1690; e-mail: wmaloney@stanford.edu. He receives royalties from Zimmer.
References:
- Keeney J, Clohisy J, Curry M, Maloney W. Efficacy of combined modality prophylaxis including short-term duration warfarin to prevent venous thromboembolism after total hip arthroplasty. J Arthroplasty. 2005;21(4):469-475.
- Maloney WJ. Venous thromboembolism (VTE) hip & knee. Presented at Orthopedics Today Hawaii 2008. Jan. 13-16, 2008. Lahaina, Maui, Hawaii.