AAOS: Risk of VTE Exists for Some Knee 'Scope Patients

medpageTODAY.com—February 21, 2011

Some patients undergoing knee arthroscopy have risk factors that warrant prophylaxis against life-threatening venous thromboembolism, researchers said here.

According to two large analyses of patient records, factors that would warrant precautionary anticoagulant treatment include a history of cancer, older age, and prior history of venous thromboembolism (VTE), investigators reported at the American Academy of Orthopaedic Surgeons meeting.

One study examined patient registry data maintained by the New York State Department of Health, covering a total of 418,323 knee arthroscopies from 1997 to 2006.

The New York study, reported by Iftach Hetsroni, MD, of Hospital for Special Surgery in New York City, focused on factors associated with diagnoses of pulmonary embolism made within 90 days of the arthroscopies.

Hetsroni said that current guidelines recommend against routine thromboprophylaxis for patients undergoing knee arthroscopy because of the bleeding risk but allow for the possibility of preventive treatment in patients with risk factors.

But the associations between those factors -- such as age and cancer history -- and VTE or pulmonary embolism in arthroscopy patients have never been firmly established, he said.

He reported such associations in 117 pulmonary embolism cases identified in the New York database, which corresponded to an incidence rate of 0.028%.

The analysis included several factors considered to be potential risk factors that were recorded in the health department database. These included operating room time, complexity of surgery, type of anesthesia, comorbidities, history of cancer, age, and sex.

Of these, Hetsroni said, surgical complexity, anesthesia type, and comorbidities turned out not to be associated with pulmonary embolism.

Of those that were, age was the most powerful predictor, he said. Compared with teenagers, individuals older than 30 had an odds ratio of 6 for pulmonary embolism (P=0.001) -- more than 7 for those older than 40, Hetsroni reported.

Odds ratios of about 3 were found for operating room time greater than 90 minutes, compared with procedures completed in less than 30 minutes (P<0.001), and for history of cancer (P=0.06). Women were at greater risk by a factor of 1.5 (P=0.03).

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