MELBOURNE – Use of a prophylactic vena cava filter to trap blood clots in severely injured patients does not appear to reduce the risk of pulmonary embolism or death, according to data presented at the International Society on Thrombosis and Haemostasis congress.
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The researchers reported the outcomes of a multicenter, controlled trial in which 240 severely injured patients with a contraindication to anticoagulants were randomized to receive a vena cava filter within 72 hours of admission, or no filter. The findings were published simultaneously in the New England Journal of Medicine.
The study showed no significant differences between the filter and no-filter groups in the primary outcome of a composite of symptomatic pulmonary embolism or death from any cause at 90 days after enrollment (13.9% vs. 14.4% respectively, P = .98).
In a prespecified subgroup analysis, researchers examined patients who survived 7 days after injury and did not receive prophylactic anticoagulation in those 7 days. Among this group of patients, none of those who received the vena cava filter experienced a symptomatic pulmonary embolism between day 8 and day 90, but five patients (14.7%) in the no-filter group did.
Filters were left in place for a median duration of 27 days (11-90 days). Among the 122 patients who received a filter – which included two patients in the control group – researchers found trapped thrombi in the filter in six patients.
Transfusion requirements, and the incidence of major and nonmajor bleeding and leg deep vein thrombosis, were similar between the filter and no-filter groups. Seven patients in the filter group (5.7%) required more than one attempt to remove the filter, and in one patient the filter had to be removed surgically.
Kwok M. Ho, PhD, of the department of intensive care medicine at Royal Perth Hospital, Australia, and coauthors wrote that while vena cava filters are widely used in trauma centers to prevent pulmonary embolism in patients at high risk of bleeding, there are conflicting recommendations regarding their use, and most studies so far have been observational.
“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,” they wrote. “Unnecessary insertion of a vena cava filter has the potential to cause harm.”
However, they noted that patients with multiple, large intracranial hematomas were particularly at risk from bleeding with anticoagulant therapy, and therefore may benefit from the use of a vena cava filter.
The Medical Research Foundation of Royal Perth Hospital and the Western Australian Department of Health funded the study. Dr. Ho reported funding from the Western Australian Department of Health and the Raine Medical Research Foundation to conduct the study, as well as serving as an adviser to Medtronic and Cardinal Health.
SOURCE: Ho KM et al. N Engl J Med. 2019 Jul 7. doi: 10.156/NEJMoa1806515.
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