Some may benefit when anticoagulants are contraindicated in first week post-injury
Early placement of an inferior vena cava (IVC) filter in trauma patients does not reduce their risk of pulmonary embolism or death, Australian researchers found.
They reported that placing a vena cava filter in severely injured patients within 72 hours of hospital admission resulted in an incidence of symptomatic pulmonary embolism or death of 13.9%, compared with 14.4% for no such placement (HR 0.99, 95% CI 0.51-1.94), reported Kwok Ho, PhD, of Royal Perth Hospital, and colleagues.
The team did find, however, that prophylactic use of an IVC filter may provide some benefit for severely injured patients who were unable to take anticoagulants in the first 7 days after injury.
The study was published online in the New England Journal of Medicine, simultaneously with its presentation at the International Society on Thrombosis and Haemostasis congress in Melbourne, Australia.
Venous thromboembolism frequently occurs in patients who experience major trauma, with one study showing that without prophylactic anticoagulation, proximal deep vein thrombosis occurs in about 18% of patients and pulmonary embolism in 11%, Ho and colleagues explained. "Therefore, effective thromboprophylaxis is of paramount importance."
At the same time, however, anticoagulation puts these patients at an increased risk of bleeding, leading many trauma centers to use IVC filters as a primary means to prevent pulmonary embolism.
"This approach has been taken despite the limited high-quality data to guide the use of these devices," the investigators noted.
Their aim, therefore, they said, was to evaluate whether early placement of these filters reduces the risk of pulmonary embolism or death in severely injured patients who have a contraindication to prophylactic anticoagulation.
The team randomly assigned 240 patients with severe injuries (median injury severity score of 27 based on a scale of 0-75) and a contraindication to anticoagulant agents to either have or not have a vena cava filter placed within the first 72 hours after hospital admission for the injury.
The primary endpoint of the study was a composite of symptomatic pulmonary embolism or death from any cause at 90 days after enrollment. A secondary endpoint was symptomatic pulmonary embolism from day 8 through 90 in patients who survived at least 7 days and did not receive prophylactic anticoagulation within 7 days after injury.
"Overall, the incidence of symptomatic pulmonary embolism or death (the primary composite endpoint) was not significantly lower among those in whom a vena cava filter was placed than among those in whom no filter was placed," Ho's group wrote.
In the subgroup of patients who survived at least 7 days and did not receive prophylactic anticoagulation within the first 7 days after injury (which included 46 patients in the IVC filter group, and 34 in the control group), no patient who received an IVC filter had a symptomatic pulmonary embolism from day 8 through 90.
However, five of the 34 patients in the control group (14.7%) did have a symptomatic pulmonary embolism during that time, all occurring from day 9 through 19. Of those 34 patients, 69% had intracranial hematomas or contusions, leading the team to suggest that this patient cohort "may benefit from the use of a vena cava filter as a temporizing measure to prevent symptomatic pulmonary embolism."
Ho and co-authors also pointed out that there are significant risks associated with IVC filters. In this study, for example, an entrapped thrombus was found in the filter in 5% of the patients.
"Given the cost and risks associated with a vena cava filter, our data suggest that there is no urgency to insert the filter in patients who can be treated with prophylactic anticoagulation within 7 days after injury," the researchers concluded.
"That's the big take-home from this study," commented Eric A. Secemsky, MD, an interventional cardiologist at Beth Israel Deaconess Medical Center in Boston, who was not involved with the study. "About two-thirds of the patients actually received anticoagulation, and this is what we think is probably sufficient to prevent the occurrence of life-threatening venous thromboembolism (VTE)," he told MedPage Today via email.
Considering that so many of the patients were receiving anticoagulation prior to IVC filter use, "it's not surprising that those randomized to filters did not get any additional benefit," Secemsky said. "Once people can be on any type of anticoagulation -- whether it is therapeutic doses for symptomatic treatment of VTE, or prophylactic doses for patients at risk for VTE -- in my mind it really removes the need for IVC filter."
"I think this [study] adds to what we already understand about how to appropriately use IVC filters," he concluded.
Ho reported financial relationships with Medtronic and Cardinal Health, and one co-author reported financial relationships with Bayer, Pfizer, and Merck.
New England Journal of Medicine
Read the original article on Medpage Today: Early IVC Filter Use Fails to Cut Embolic Risk After Trauma