Thromboembolism remains an important complication in knee and hip arthroplasty

KOHALA COAST, Hawaii — Even though the American Academy of Orthopaedic Surgeons (AAOS) has made recommendations for pulmonary embolism (PE) prophylaxis, researchers are still seeking the optimal postsurgical prophylaxis regimen, according to a former AAOS president.

“When we consider the American College of Chest Physicians (ACCP) guidelines and the AAOS guidelines, there is nothing perfect here,” Richard F. Kyle, MD, said during a CME luncheon on deep vein thrombosis (DVT), held during Orthopedics Today Hawaii 2009. “This needs to be looked at carefully and improved upon. The problem is thromboembolism remains an important complication following total hip and knee replacement.”

Kyle noted that the ACCP guidelines are more aggressive than the orthopedic standards, but many hospital oversight groups and governmental agencies have adopted them as the new standards. That decision was largely based on the 1A rating the ACCP gave to certain pharmacoprophylaxes due to the amount of randomized clinical trials that advocate their use in the literature.

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“These evaluations are expensive, which sort of tilts this toward the pharmaceutical companies that can afford them,” he said. “Research into the low-cost options such as aspirin and pneumatic compression devices is probably unlikely to reach a 1A level. This may result in high-level recommendations for aggressive standards compared to orthopedic standards.”

Aggressive pharmacoprohphylaxis has been associated with high complication rates in recent studies, Kyle said.

In response to these problematic protocols, the AAOS developed a work group to assess the available evidence, focus on PE and death as endpoints, and minimize risk as well as maximize efficacy. To do this, they classified patients on a risk-for-PE and a risk-for-bleeding basis.

“They based their recommendations on relative risk using a more rational approach, rather than [making] uniform recommendations for all patients,” Kyle said. “The recommendations are based on cohort studies because there are almost no randomized, prospective trials that really sort this information out, looking at fatal pulmonary emboli and the risk of complications.”

The top four AAOS recommendations are:

• Patients at standard risk for both PE and major bleeding should be considered for aspirin, low -molecular-weight heparin (LMWH), synthetic pentasaccharides and warfarin.
• Patients who have an elevated risk for PE and a standard risk of bleeding should be considered for LMWH, synthetic pentasaccharides and warfarin.
• Patients at a standard risk of PE and an elevated risk of bleeding should be considered for aspirin and warfarin.
• Patients at an elevated risk for both PE and bleeding should be considered for aspirin and warfarin.

Kyle said orthopedic surgeons can view 10 other recommendations at the AAOS Web site (www.aaos.org).

“The AAOS guidelines seek to minimize clinically relevant thromboembolism while also minimizing complications. That is where we run into trouble with the guidelines from the chest physicians,” he said. “They don’t see the complications that we see and the effects of a large bleed or infections.”

Following the ACCP guidelines is not necessary to meet federal programs, according to Kyle.

“For total knees, mechanical devices can meet those standards. They [the ACCP] state that you do need prophylaxis, but you have an array of items that you can use,” he said. “Also, there is no listed dosage. You can use warfarin at a lower international normalized ratio. I use it somewhere between 1.5 and 1.7.”

The luncheon was supported by an educational grant from Sanofi Aventis.

Reference:

• Kyle RF. ACCP & AAOS guidelines for DVT prophylaxis and treatment: What’s the difference? Presented at the DVT prophylaxis and treatment in the surgical setting luncheon at Orthopedics Today Hawaii 2009. Jan. 13, 2009. Kohala Coast, Hawaii.