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Carefully weigh the benefits and risks of prophylaxis for thromboembolic disease
Paul A. Lotke, MD, gives his advice and opinions on the current DVT prevention recommendations.
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During the past 30 years in orthopaedic surgery, we have seen many recommendations regarding DVT and PE management presented, revised and lost from favor. Even today, we have differing opinions and practices in this area as to what is the most effective prophylaxis and treatments for orthopaedics patients. I am pleased to share in this month’s interview some thoughts from Dr. Paul Lotke on this subject. I have found over the years his thoughtful, methodic and questioning interpretation of existing data to be insightful.
Douglas W. Jackson, MD — Many of the medical consultants uniformly apply the guidelines from the Chest physicians’ recommendations. Are these directly applicable to the postoperative total joint patient?
Paul A. Lotke, MD — As noted in a response to an editorial in the April 2006 Journal of Arthroplasty, the recommendations published in the Chest journal may encounter resistance in the orthopedic community because they focus too narrowly on the effort of chemoprophylactic agents in reducing deep vein thrombosis (DVT), rather than on overall patient outcomes.
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They also rely too heavily on DVT as the marker of a patient at risk and do not fully assess the side effects from increased bleeding.
Most of the large clinical trials that demonstrate a reduction in DVT are comparative drug studies that are designed to compare anti-coagulant drugs and use DVT to assess their effectiveness. However, these studies are not designed to determine the clinical outcomes of the total joint patient. The results are not analyzed by clinically important determinants such as the final results of those patients who have significant bleeds; the effects of minor bleeding and range of motion; wound healing problems; medical complications; and whether there is a diminution in the success of the surgery.
Furthermore, many of the studies comparing anti-coagulant drugs utilized selective populations of the healthiest patients. They do not represent our total population, and therefore underestimate the risk of bleeding. We must carefully balance our risks and benefits. The science that optimistically claims a reduction in DVT as a final clinical measure, without considering the clinical outcomes for the total joint patient, is flawed. It should not be the only determining factor in how to best serve the interests of our patients.
Jackson — Is ultrasound or venographic demonstration of a DVT a predictor risk of pulmonary emboli (PE)?
Lotke — A direct association of the presence of DVT and subsequent PE after total joint surgery has not been demonstrated. This is primarily due to the fact that there is a relatively high prevalence of DVT and a very low prevalence of PE.
If DVT were accurate markers for the patient at risk after total joint surgery, then the incidence of PE and fatal PE would decline proportionately with a reduction of DVT. This has never been shown. In fact, DVT are two to three times more common after total knee than total hip arthroplasty, but the total knee patients have fewer PE, not a two to three fold increase.
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As the prevalence of DVT is high, randomized controlled drug comparisons utilize DVT as an assay as to the effectiveness of a specific drug regime. Unfortunately, the presence, absence or reduction in DVT has been translated into a clinical outcome. However, this analysis ignores the lack of a direct association and the results of adverse events, such as bleeding, on clinical outcomes.
Jackson — What are some of the difficulties in doing definitive studies in orthopedics resulting in evidence based decision guidelines?
Lotke — In brief: There is a low incidence of the problem, and the cost. The incidence of PE and fatal PE is so low, less than 1% and 0.1% respectively, generating the number of patients required to show a 50% reduction in PE would require 10,000 patients and more than 100,000 patients would be required to show a 50% reduction in fatal PE. Clearly, these numbers are too large to design a practical study, which uses PE as a clinical outcome.
This is the reason that the drug companies measure DVT after total knee arthroplasty (TKA). DVT after TKA has a high prevalence and they can show statistical differences. Unfortunately, as mentioned above, the DVT results have been translated into clinical outcomes and clinical recommendations.
Jackson — What are some of your opinions for balancing the risks and benefits for prophylaxis?
Lotke — First, we must recognize that the risks from PE have been significantly reduced by our changing clinical practices. Currently, we rapidly mobilize our patients, we have increased use of regional anesthesia, better surgical techniques with less tissue trauma, compression devices, and better pain management that allows early mobilization. These practices contribute significantly to the reduction in thromboembolic disease. Therefore, aggressive chemoprophylaxis, with its inherent risk of bleeding, is no longer indicated for our routine total joint patients.
The very low incidence of thromboembolic disease demonstrates the effectiveness of our current clinical practices. These improvements alter the risk versus benefit ratios. We should think cautiously before accepting drug guidelines, which significantly increase the risk of bleeding and where the benefits cannot be measured.
There is a “multi-modal” approach to thromboembolic disease, which is gaining wide support. In this regime, the aggressive chemoprophylactic agents are reserved for surgically defined high-risk patients, such as those with known thrombophilia or those with prior documented PE. However, the majority of our patients (85-95%), can be managed with less risky agents such as low dose warfarin or aspirin. This approach, in association with current clinical practices, is producing excellent clinical outcomes with significantly reduced risks from bleeding and PE.
For more information
- Paul A. Lotke, MD, is with the Department of Orthopaedic Surgery, Delaware County Memorial Hospital. He can be contacted at 610-449-0970, or paul.lotke@uphs.penn.edu.