Innovator Rothman chooses low-dose warfarin in joint replacement cases

More than 30 years of experience and 20,000 patients give him ‘a lot of judgment.’

LAS VEGAS – With 30 years of experience, one surgeon said he sees warfarin as the best choice for venous thromboembolism and pulmonary embolism prevention.

“If the goal is to prevent fatal pulmonary embolism, and that is my goal, I think Coumadin (warfarin sodium, Bristol-Meyers Squibb) provides almost absolute immunity,” Richard H. Rothman, MD, PhD, said during the American Academy of Orthopaedic Surgeons 76th Annual Meeting.

Rothman discussed his own experience as well as the experience garnered at his institution where more than 20,000 total joint replacement (TJR) patients have been seen, explaining how he and his colleagues came to their current treatment conclusions.

Experience

: “Essentially, the problem we wrestle with is the risk of bleeding with anticoagulation.”; — Richard H. Rothman, MD, PhD

Rothman and colleagues at Thomas Jefferson University Hospital, Philadelphia, have always monitored their patients for clot complications, but their methods have changed.

Over the years, monitoring protocols have evolved, from performing lung scans, to arteriograms, to spiral CT scans and then multidetector CT scans.

After Rothman and colleagues looked at the incidence of pulmonary emboli over the years, particularly at the different markers, he said, “There is an apparent increase in the rate of pulmonary emboli when you move from [lung ventilation/perfusion] scans to spiral CT to multidetector CT. ... We saw this tremendous increase in the frequency of pulmonary emboli, [but] the death rate remained the same.”

The implication is that the statistics may depend on the tool used to measure effectiveness, Rothman said. With that in mind, the investigators looked at the problems of hematoma and bleeding in TJR patients.

“Essentially, the problem we wrestle with is the risk of bleeding with anticoagulation. ... The risk of hematoma moves up substantially when you go to full-dose Coumadin,” Rothman said.

Research has led Rothman to conclude that a low dose of warfarin is the best choice for preventing thrombolic events after arthroplasty.

In published data looking at patients with sepsis after undergoing total joint replacement, Rothman and colleagues concluded that many cases were preceded by hematoma related to a high international normalization ratio (INR) of warfarin.

“If you’re going to go up to [high] therapeutic levels, your patients are going to pay a price, not only of hematoma but also sepsis,” he said.

Coumadin is also associated with a lower range of pulmonary embolism than aspirin.

“This is the nail in the coffin for Coumadin related to aspirin for us,” he said.

Current treatment algorithm

: “Our experience spans 30 years. That gives you a lot of judgment.”; — Richard H. Rothman, MD, PhD

Rothman’s group uses the AAOS guidelines as a basis for their goal INR range of 1.5 to 2, rather than the American College of Chest Physicians guidelines of INR of 2 to 3.

To achieve their goal, they administer 10 mg Coumadin the night of surgery, abstain from treatment the next night and then begin treating with Coumadin until reaching the desired INR.

A patient who shows signs of pulmonary embolism (PE) remains on Coumadin for 6 weeks. If PE develops within the first 2 weeks postoperatively, the surgeons implant a filter and continue Coumadin. If 2 weeks have passed before a PE is evident, the patient would then receive a higher dose of Coumadin to achieve a therapeutic level.

Risk factors for development of PE include older age, prolonged surgery and general anesthesia, Rothman said. Conversely, prior PEs, varicose veins, prior deep venous thrombosis and arterial disease do not appear to be predisposing risk factors while on Coumadin, he said.

“Our experience spans 30 years. That gives you a lot of judgment — 20,000 total joint patients in our complex,” Rothman said. Over that time, he and his colleagues have developed a “strong bias” for low-dose Coumadin.

“It does not mean that it is the only solution, but our group can speak with great personal certainty that it works and it is safe,” he concluded.

For more information:

Richard H. Rothman, MD, PhD, can be reached at the Rothman Institute, 925 Chestnut St., 5th Floor, Philadelphia, PA 19107; 267-339-3500. He has no direct financial interest in any products or companies mentioned in this article.

References:

Pulido L, Parvizi J, Macgibeny M, et al. In hospital complications after total joint arthroplasty. J Arthroplasty. 2008;23:139-145.
Rothman RH. The prevention of pulmonary embolism with low dose Coumadin. Presented at the American Academy of Orthopaedic Surgeons 76th Annual Meeting. Feb. 25-28, 2009. Las Vegas.