A recent study conducted at the Boston University School of Medicine has found that inferior vena cava (IVC) filters are not only dangerous – they’re virtually useless. The study, led by Dr. Shayna Sarosiek, was published last week in JAMA Surgery.

Researchers examined records of trauma patients who received IVC filters in order to prevent blood clots from traveling to the lungs and causing pulmonary embolism. Their conclusion: there was “no significant difference in survival in trauma patients with versus without placement of an IVC filter, whether in the presence or absence of venous thrombosis.”

The findings give serious cause for concern, because of the growing practice of implanting IVC filters into trauma patients who are admitted to emergency rooms. IVC filters have long been used in patients who have undergone joint replacement surgery in order to reduce the risk of embolism. However, these devices were not designed for long-term placement. The problem is that once implanted, they are very difficult to remove. They are known to come loose and even fall apart, sending small, sharp bits of metal through the circulatory system, causing serious injury.

In recent years, emergency room physicians have been implanting IVC filters in patients with serious injuries. As is the case with joint surgery patients, the reason is to reduce the risk of embolism. However, this is not what Dr. Sarosiek and the research team have discovered. Studying the records of trauma patients who were still alive 24 hours following their injury, they found no correlation between the use of IVC filters and survival rates. This was true whether or not these patients already had deep vein thrombosis (blood clots) or an embolism prior to receiving the filter. Furthermore, there was no evidence that IVC filters had any impact on patients’ long-term survival.

What is particularly alarming is that in 92% of cases, these filters remained inside the patients as much as four years later. The danger is that the longer the IVC remains implanted, the greater the chances of it tearing loose and migrating or shattering. In the published study, the researchers state that “given the expected morbidity of long-term IVC filter use, filters should be removed as soon as a patient’s contraindication to anticoagulation resolves.”

Unfortunately, this is not easy. Despite increasing calls for the expeditious removal of IVC filters, only 20% of them are ever removed. In some cases, these filters have remained inside a patient for as long as ten years. What is even more shocking is that some patients – particularly those who have suffered trauma – may not even be aware that they have an IVC filter.

Commenting on Dr. Sarosiek’s research in an editorial, two VA physicians, Drs. Paul Waltz and Brian Zuckerbraun, agreed that “routine use of IVC filters in trauma patients is not indicated.”

The published study can be accessed online at the JAMA Surgery website.