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DVT prophylaxis: What is your treatment choice?

Issue: November 2007

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As clinicians performing joint replacement surgery, deep venous thrombosis (DVT) and a possible embolus and/or a post-phlebitis syndrome (persistent swelling in the involved lower extremity) are of real concern.

There remains a spectrum of proposed treatments and much difference in opinions on balancing the risks, costs and duration of treatment, as well as which is the best agent to give the optimal patient care.

During my career, the consensus has changed several times for the best DVT prophylactic approach. It has merited much discussion, numerous articles and the continuing advent of new treatments to compare and contrast to previous treatment standards.

We can all agree upon the basic concerns related to this topic, but consensus has been a moving target in the search for the ultimate approach for DVT prophylaxis.

We all want to minimize the risk to our patients from the possible sequelae of DVT and at the same time minimize the risk of the prevention treatments. In the current medical-legal environment, we need to

demonstrate that we have considered the options and made our choices based on some existing data, experience and literature. Because most of us struggle deciding which is the best possible management, I have turned to some experts, who happen to also be friends, whose experience and opinions on how they approach DVT prophylaxis in their patients I respect.

The purpose of this Round Table discussion is to demonstrate that a full-spectrum of treatment options still exists, even among experts. Let me offer this as a disclaimer for all of them: each panelist responded to some succinct questions and is not able, in the confines of this format, to present his entire thinking on this subject. This discussion is presented to stimulate your thinking and to get you to critique what you are currently using in your patient care. For more definitive information, please pursue the topic further in the literature as well as what Orthopedics Today has presented in the past and the Point/Counterpoint articles of this issue.

Douglas W. Jackson, MD
Chief Medical Editor

Douglas W. Jackson, MD: Paul Lotke, MD, what specific DVT prophylaxis are you currently using in your patient care?

Paul A. Lotke, MD: I use aspirin, 325 mg twice daily, for 6 weeks beginning on the night of surgery for both total knee arthroplasty (TKA) and total hip arthroplasty (THA). The only deviations in this protocol are for patients on chronic warfarin prophylaxis for cardiac arrhythmias. In these patients, I discontinue the warfarin four days prior to surgery and resume their maintenance dosage the night of surgery. The other deviation is for the rare patients with a proven prior pulmonary embolism (PE) or a known thrombophiliac. In those patients, who have a real risk of activating their hypercoagulable state, I will use a low molecular weight heparin (LMWH) beginning the morning after surgery. In the few patients who have aspirin intolerance, I reduce the dosage to 81 mg per day.

Jackson: You have long been a proponent of aspirin. Could you restate your thoughts for our readers?

Lotke: I prefer the use of aspirin because it is safe and offers equal protection from PE as do the other current choices. Warfarin is fine, because it also has low bleeding rates, but the dose-response is so variable that it is difficult to manage. The LMWHs lower the risk of DVT, but not PE, and have an unacceptable major bleeding risk. The prevalence of increased bleeding and wound complications from these agents has not been fully assessed and may significantly diminish outcomes. The research publications on these agents have only looked at DVT as the primary result. They have not looked at the other outcomes that are important to the surgeon, like wound problems, motion, infection, analgesia and anesthetic choices, etc. Balancing all the risks to all the benefits, I continue to use aspirin.

The contraindications to aspirin are few and my only exceptions to its use are noted above

Jackson: Tom Schmalzried, MD, what are you currently using in your practice?

Thomas P. Schmalzried, MD: At this time, for total hips I give Lovenox (enoxaparin sodium injection, Sanofi Aventis), 20 mg 24 hours after surgery, then 40 mg once daily (qd) for 3 weeks. For total knees, I give Lovenox 20 mg 24 hours after surgery then 40 mg qd for 10 days. For professional liability reasons, my protocol is based on the American College of Chest Physicians (ACCP) recommendations. I am not happy about wound hematomas, ecchymosis, drainage and delayed wound healing that are definitely an issue with all the injectables, especially with knees (hence the low first dose). I think that the ACCP analyses do not appropriately weigh the longer-term impact of these wound issues. It is likely that I will change to the recommendations in the American Academy of Orthopaedic Surgeons (AAOS) clinical guidelines.

Jackson: Cliff Colwell, MD, what have you gone through to arrive at your current venous thromboembolism (VTE) prophylaxis regime?

Clifford W. Colwell Jr., MD: There has been excellent data gathered since 1986 at the time of the NIH conference on venous thromboembolic disease (VTED). The randomized studies that evaluate the benefit of the modality against the risk, place four different regimes at the highest level for efficacy and safety: the two approved LMWHs, enoxaparin and dalteparin, fondaparinux and appropriately dosed warfarin.

Jackson: What are your current protocols?

Colwell: We use subcutaneous enoxaparin 30 mg every 12 hours for 10 days starting the morning after surgery. This specific regime is used because it is highly rated and because of the discount that the hospital gets in cost, due to the fact that all of the services in the hospital use enoxaparin for prophylaxis and treatment. Patients with very severe risks, ie, solid malignancy within 5 years, return for duplex ultrasound at 10 days and continue to treat with warfarin if duplex is positive.

Contraindications include:

• bleeding dyscrasia;
• allergy to heparin products;
• history of heparin induced thrombocytopenia (HIT); and
• failed previous LMWH prophylaxis.

We use this prophylactic regimen because of the results of all the prospective randomized studies worldwide that weighed risk and benefit ratio and because enoxaparin is the most used drug worldwide for prophylaxis in hip and knee replacement. We use prophylaxis to prevent distal and proximal DVT, PE, and fatal PE. DVT has been used in prophylaxis studies as a marker for PE and although not perfect, we currently have no better marker and studies have shown the marker of DVT to have good specificity, sensitivity and accuracy.

Presently, clinical trials for the oral direct 10A inhibitors that do not require monitoring are being conducted in phase III trials as the phase II trials looked excellent. I have recently been looking at a new portable compression device.

Jackson: William Robb, MD, what has been your experience at arriving at a protocol for a large institutional setting?

William J. Robb III, MD: For the past 15 years the DVT/PE prophylaxis program for total joint replacement patients at Evanston Northwestern Healthcare (ENH) has evolved to effectively reduce the incidence of DVT/PE. The overall incidence of all postoperative DVT/PE, symptomatic and asymptomatic, is less than 5% with the incidence of fatal PE <0.1%.

The goal of the current ENH anticoagulant program for DVT/PE prophylaxis following THA or TKA is to minimize the incidence of DVT and PE and at the same time minimize complications resulting from anticoagulation and resultant post operative bleeding based upon the calculated assessment of risk.

Jackson: How do you assess patient risk and how do you use that information?

Robb: All THR/TKR patients are evaluated preoperatively and stratified based upon preoperative risk assessment.

Low-risk patients have no, or low, cumulative risk factor total.

Factors for an increased cumulative risk factor total include: varicose veins; chronic venous stasis disease; lower extremity edema; history of recent surgery – 1 month; history of recent or remote malignancy; obesity indicated by a BMI > 30; increased age; use of drugs such as birth control or hormone therapies; current or recent inflammatory or infectious process and current immobility.

Higher-risk patients have a high cumulative total of the previously mentioned factors and/or a history of previous DVT/PE or a family history of DVT/PE.

All patients are rated based upon a cumulative score of risk factors and are treated differentially with combined mechanical and pharmacological prophylaxis.

All low-risk patients are given compression hose, which are placed on both legs and continued throughout the period of anticoagulation. Compression boots are placed on the well leg intraoperatively and both legs postoperatively during hospitalization. Coumadin (warfarin sodium, Bristol-Myers Squibb) is started the evening of surgery with a goal of reaching an International Normalized Ratio (INR) of 1.5 to 2 at the time of hospital discharge, usually on the morning of postoperative day 3. Unfractionated, subcutaneous heparin is used as a bridge beginning 12 hours after surgery and continued until the INR reaches 1.5. Anticoagulation with Coumadin is maintained for 3 weeks for TKA patients and 6 weeks for THA patients.

Increased risk patients are given compression hose and compression boots intraoperatively and postoperatively during the hospitalization. Postoperatively, increased risk patients are given Coumadin the evening of surgery with a goal of reaching an INR of 1.5 to 2 by the time of discharge, normally the morning of postoperative day 3. LMWH is used as a bridge beginning 12 to 24 hours after surgery and continued until the INR reaches 1.5 to 2. Anticoagulation with Coumadin is continued for 3 months postoperative.

High risk patients are seen preoperatively in consultation by the vascular service. The preoperative evaluation includes a workup for identifiable hypercoagulability and venous Doppler of the lower extremities. High risk patients are counseled about the perioperative risks. DVT/PE prophylaxis for high risk patients may include the following:

• preoperative placement of an IVC filter;
• perioperative LMWH as the primary anticoagulant;
• intraoperative and perioperative mechanical compression;
• postoperative venous Doppler at hospital discharge; and
• extended pharmacologic anticoagulation for 3 to 6 months.

All appropriate patients are offered regional anesthesia and are mobilized from bed as soon as possible following surgery. All patients are counseled about the risks of DVT/PE and the risks of bleeding from pharmacologic anticoagulation. Frail or patients older than 80 years, are anticoagulated carefully particularly when Coumadin is the primary anticoagulant.

Coumadin has been used primarily because the pharmacologic effect is not immediate (decreasing the risk of postoperative bleeding) and it is a covered drug in the Medicare program. LMWHs have been effective, but have had a small incidence of idiosyncratic perioperative bleeding. Until recently, they have not been covered by Medicare.

Jackson: David Mauerhan, MD, what is your preference for prophylaxis against DVTs in your postoperative joint replacement protocol?

David R. Mauerhan, MD: I’ve been prophylaxing my THAs and TKAs the same way for quite some time now. I use Lovenox 40 mg daily, starting on postoperative day 1. I use sequential compression devices (SCDs) on everyone while in the hospital. I continue the Lovenox for 14 days post discharge. So in essence, everyone gets about 16 to 18 days of Lovenox. If patients cannot tolerate Lovenox due to previous heparin-induced thrombocytopenia (HIT) reaction or the platelets fall below 100,000, then I would use Coumadin — although this has been very rare in my experience. Following the Lovenox after discharge, I ask patients to take aspirin 325 mg daily for an additional month.

Jackson: What are some of the reasons you prefer Lovenox and some of your concerns?

Mauerhan: I use Lovenox, because it is easy to administer and does not require any significant monitoring other than the platelet check, and the literature shows it to be effective. Although Coumadin is quite effective as well, blood draws and monitoring INR are more imposing to the patient. There is also the problem that many patients are subtherapeutic with the INR and the occasional patient whose INR is way out causing late bleeding. The Lovenox followed by aspirin is relatively safe and convenient for patients.

There is no question that Lovenox can lead to more perioperative bleeding and lower postoperative hemoglobins. Wound drainage must be managed aggressively, even if it means stopping physical therapy for several days until the wound seals. If it continues 7 to 10 days, irrigation and debridement should be carried out. Fortunately for me this has been very rare. One needs to pay attention to the platelet level while in the hospital. If it is falling, then it should be checked to ensure that platelets stay above 100,000. We have a good teaching program in the hospital and through the clinic to help patients with this process which is important for good compliance.

Jackson: Why have the current SCIP VTE (Surgical Care Improvement Project, Venous Thromboembolism) guidelines been accepted by our hospitals for orthopedic care with very little input from orthopedic surgeons? What might we do in response?

Mauerhan: It seems the current SCIP VTE guidelines were integrated into almost every hospital’s routine order sets for fear of being penalized by the Centers for Medicare & Medicaid Services and shortly thereafter, the private carriers. As an example, I have always been intrigued by Paul Lotke’s approach, and he now has a series of 3,000 patients to back up his stance. The problem is how do we get the ACCP and others such as the American Medical Association (AMA) Consortium to look at these alternatives to change? The burden is on us in orthopedics, as an organized force, to push for change in the current guidelines based on evidence. Clearly, the medical doctors will only look at DVT and PE as their endpoint and they do not see the wound complications secondary to bleeding like we do. It is beyond the scope of this roundtable discussion, but the issues of optimal DVT prevention for orthopedic patients will be contentious for some time to come. I sit on the AMA Consortium as a representative from American Association of Hip and Knee Surgeons (AAHKS) and I know there is a mechanism to change guidelines when there is evidence to do so, but it will take a concerted effort.

For more information on DVT prophylaxis, see our Point/Counterpoint articles.

For more information:

• Clifford W. Colwell Jr., MD, can be reached at Scripps Clinic Torrey Pines, 10666 N Torrey Pines Road, MS 116, La Jolla CA 92037; 858-554-8852; e-mail: cliffcolwellmd@yahoo.com. He receives institutional support from Astra Zeneca, Bayer Healthcare, Sanofi Aventis and Boehringer/ Douglas W. Jackson, MD, can be reached at Memorial Orthopedic Surgical Group, 2760 Atlantic Ave., Long Beach, CA 90806-2755; 562-424-6666; e-mail: jacksondw@aol.com.
• Paul A. Lotke, MD, professor of orthopedic surgery, University of Pennsylvania, can be reached at Delaware County Memorial Hospital, 510 Darby Road, Havertown, PA 19083, 610-449-0970, Paul.Lotke@uphs.upenn.edu. He has indicated that he is a consultant for DePuy and Stryker.
• David R. Mauerhan, MD, can be reached at Carolinas Medical Center-Orthopedic Surgery, 1000 Blythe Boulevard, #503, Charlotte, NC 28232; 704-355-5982; e-mail: david.mauerhan@carolinashealthcare.org.
• William J. Robb III, MD, can be reached at Evanston Hospital, Walgreen Building, 2650 Ridge Ave., Suite 2505, Evanston, IL 60201; 847-570-2959; e-mail: wrobb@ibji.com.
• Thomas P. Schmalzried, MD, associate medical director, Joint Replacement Institute, 2400 S. Flower Street, Los Angeles, CA 90007; 213-742-1075; Schmalzried@earthlink.net. He has a consulting relationship with DePuy, a Johnson & Johnson company, and Stryker.