Study Probes Use of Filter Device to Stop Deadly Blood Clots

Hospitals' use of vena cava filters varies widely, probably because evidence is lacking of benefit.

MONDAY, March 18 (HealthDay News) -- The use of a special filter to prevent potentially deadly blood clots from traveling to patients' lungs varies widely among hospitals, a new study finds.

A vena cava filter is placed in the inferior vena cava, the large vein in the abdomen that returns blood from the lower body to the heart. It is one of the treatments for people with blood clots that develop in the veins of the leg or pelvis (deep vein thrombosis).

These blood clots can break free and travel to the lungs, where they can cause severe complications or death. A vena cava filter, which is designed to trap these clots before they reach the lungs, may be the only treatment option for patients who can't be given blood-thinning drugs.

But one expert notes that the evidence around the effectiveness of these devices has never been clear.

"Vena cava filters were once thought to be lifesaving devices in patients [with clots] who could not tolerate the methods of blood thinners," explained Dr. Alisha Oropallo, director of wound care and hyperbarics at North Shore-LIJ Health System, Lake Success, NY.

However, "more recent data has come to light which leads physicians to question the true efficacy of vena cava filters," she said.

In the new study, researchers looked at the use of vena cava filters at 263 hospitals in California between January 2006 and December 2010. The data showed that vena cava filters were used in nearly 15 percent of more than 130,000 hospitalizations for deep vein thrombosis.

However, the frequency of vena cava filter use at the hospital varied widely, ranging from 0 percent to nearly 39 percent of deep vein thrombosis cases. Patient factors associated with the use of vena cava filters included: bleeding at the time of hospital admission; a major operation after admission for deep vein thrombosis; having advanced cancer; and being extremely ill.

Hospital characteristics associated with the use of vena cava filters included having a small number of beds and being in a rural area, according to the study published online March 18 in the journal JAMA Internal Medicine.

The findings suggest that the use of vena cava filters is largely based on a hospital's culture and practice patterns, according to Dr. Richard White, of the University of California, Davis, and colleagues.

Hospitals may be more or less reluctant to use the filters because the data on their effectiveness remains unclear, the researchers said. "The absence of reliable data indicating a clear benefit [or clear harm] associated with [vena cava filter] use likely contributes to the wide variation in use that we observed," they concluded.

Oropallo agreed. "The need for a proper randomized trial [into vena cava filter use] is necessary," she said. "Until such studies are completed, it will remain difficult for physicians to properly guide their patients to the appropriate treatment for certain circumstances."

More information

The American College of Radiology, Radiological Society of North America has more about vena cava filters.