Permanent vena cava filters reduce the risk of pulmonary embolism (PE) but increase the risk of deep vein thrombosis (DVT) and have no effect on survival, researchers say. The findings of this 8-year study reinforce those of a previous study that followed patients for 2 years.

In the new study, 400 patients with proximal DVT with or without pulmonary embolism were randomly assigned to receive or not receive a filter in addition to anticoagulant treatment for at least 3 months. Researchers collected data on vital status, venous thromboembolism, and postthrombotic syndrome every year for up to 8 years. They found that:

* symptomatic PE occurred in 6% of patients in the filter group and 15% of those in the nonfilter group

* deep vein thrombosis occurred in 36% of the filter group and 28% of the nonfilter group

* rates of postthrombotic syndrome and mortality were similar in both groups.

Researchers say that although the use of filters may help patients at high risk for PE, they don't recommend routine use of filters for all people with venous thromboembolism.

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