MIAMI BEACH – An internist and an orthopedic surgery recently squared off on the best strategy to prevent deep vein thrombosis following major joint-replacement surgery.
Anticoagulant agents effectively prevent deep vein thrombosis (DVT) after total hip replacement or total knee replacement, according to a large body of scientific studies, the internist argued. In contrast to the well studied, relatively small number of anticoagulants, the myriad of mechanical devices are supported by more limited, less rigorous research in the medical literature, Dr. James D. Douketis said at a meeting on perioperative medicine sponsored by the University of Miami.
Dr. James Douketis
The risk of major or clinically relevant bleeding associated with anticoagulant use can be minimized with appropriate administration, such as waiting at least 12 hours after surgery to start therapy, said Dr. Douketis, director of the vascular medicine program at St. Joseph’s Healthcare in Hamilton, Ont.
"I agree that the bleeding risk is relatively low if these drugs are used properly, but why do you have to take any risk?" orthopedic surgeon Dr. Clifford W. Colwell Jr. asked at the meeting.
Most bleeding episodes, when they do occur, are easy to mitigate, Dr. Douketis said. Unlike DVTs, most of these events do not have long-term consequences, he said. In addition, mechanical methods are not always benign. There are reports of trauma associated with use of intermittent compression devices, for example.
Dr. Colwell countered that a zero risk of an adverse bleeding event is one of the main benefits of mechanical devices to prevent DVT. For this reason, these devices are ideal for patients at a high risk for bleeding who cannot take anticoagulants, he said. Enhancement of the effectiveness of drug-based thromboprophylaxis and reduced leg swelling are other potential benefits of these devices.
The effectiveness of mechanical compression devices is directly correlated with how much time they are worn and these devices are nearly complication free, said Dr. Colwell, medical director at the Shiley Center for Orthopaedic Research and Education at Scripps Clinic in La Jolla, Calif.
But why can’t these devices be more portable? The ActiveCare+S.F.T. Portable Intermittent Compression Device, or PICD (Medical Compression Systems Ltd.), is a miniature, battery-powered device that overcomes a major limitation of some mechanical devices: Their design and size can impede ambulation after surgery. The PICD can be worn out of bed and out of the hospital, Dr. Colwell said. It synchronizes compression with the patient’s respiratory phase so it provides a naturalistic phasic venous flow.
Dr. Clifford W. Colwell, Jr.
An initial study of its efficacy in 121 patients "was small ... I was not convinced," Dr. Colwell said (J. Arthroplasty 2006;21;206-14). A more recent multicenter, prospective study that Dr. Colwell performed with his associates compared effectiveness of the portable device to low-molecular-weight heparin for 10 days for total hip arthroplasties and was more compelling (J. Bone Joint Surg. Am. 2010:92:527-35).
At 3 months, the DVT rate was "essentially the same" at 4.1% in the device group compared with 4.2% in the anticoagulant cohort. There was no fatal PE or any deaths among the 410 randomized participants. In addition, major bleeding occurred for 0% of the device wearers and 5.6% of the pharmacologically treated patients.
"I acknowledge that mechanical prophylaxis has a role after major orthopedic surgery major, but it’s a second-line strategy," said Dr. Douketis, who also is on the medicine faculty at McMaster University. Pharmacologic prophylaxis should be first-line therapy because it has been shown to prevent DVT, and pulmonary embolism (PE), including fatal PE, he said.
A meta-analysis Dr. Douketis performed with his colleagues showed extended duration prophylaxis with heparin or warfarin significantly decreased the frequency of symptomatic venous thromboembolism, compared with placebo after total hip or knee replacement (Lancet 2001;358:9-15).
There is less confidence about prevention of proximal DVTs with mechanical devices, Dr. Douketis said.
The risks should be weighed against this efficacy, Dr. Douketis said. In a study, researchers determined the risk of major or clinically-relevant bleeding was 4% of 1,501 patients treated with apixaban and 5% of 1,508 patients treated with enoxaparin (Lancet 2010;375:807-15).
American College of Chest Physician (ACCP) guidelines recommend use of low-molecular weight heparin to prevent DVT in these surgical populations but list a number of other pharmacologic prophylaxis options (supported by grade 2C/2B evidence). They also recommend addition of an intermittent pneumatic compressive device during the hospital stay of patients taking anticoagulants, but supported by grade 2C evidence. The authors also recommend one of these devices or no prophylaxis for patients at increased bleeding risk (again, grade 2C evidence). The full recommendations were published in February (Chest 2012;141:e278S-325S).